text:
King's alternative routes to reach a destination square
What are the alternative routes that  king can go to destination square like king can go from one edge to another edge in 7 moves but it has many alternative paths to reach there in 7 moves.
Please provide one or two practical endgame examples in which going through an alternative route makes a difference.

See also https://oeis.org/A002426 for the enumeration problem (number of n-step King paths that move from a1 to a(n+1) on an infinite board)

Brian's answer is sufficient, but I like to extend it with a few observations that are too long for a comment.

"edge, 7 moves, alternative path" is a bit unprecise: if the edges are diagonal, of course the shortest path is unique.
OK, assume start and destination are given. How do you actually compute the number? This can be done with Pascal's triangle technique. Assume you want to go from e3 to e7 to keep it simple. Then d4,e4,f4 get a "1" (only one path that leads there). c5 gets "1" (ditto) but d5 "2" (accessible from d4 and e4, so sum) and e5 "3". And so on, e7 gets "19" and that is the total number of shortest paths.
Brian's example does not tell you "why" of it. There are the following main reasons for picking a certain route of several possible:
Mutual Zugzwang. This happens even in the simplest KP/K endgames, thus you may choose a path catching the opponent K on the wrong foot.
Multitasking. For example, the famous Reti KP/KP study. The king marches diagonally since on this path it can fulfil two purposes at the same time, hunting the enemy pawn and supporting its own.
Shouldering. Arguably a special case of the former. You walk the path that on the same time denies the enemy K some squares. A study with only KP/KP exists for this either.
Check avoidance. It can happen that squares on your routes are "mined" for some tactical reasons, mostly an enemy check winning a tempo. Well, just march around them.

The main important difference is that the diagonal is the same number of moves as the orthogonal.

Please provide one or two practical endgame examples in which going through an alternative route makes a difference

[fen "K7/6p1/7p/8/8/8/7P/k7 w - - 0 1"]

1. Kb7 (1. Kb8 h5 2. Kc8 h4 3. Kd8 g5 4. Ke8 g4 5. Kf8 g3 6. hxg3 hxg3 7. Kg8 g2 8. Kh8 g1=Q) h5 2. Kc6 h4 3. Kd5 g5 4. Ke4 g4 5. Kf4 g3 6. hxg3 h3 7. Kf3 h2 8. Kg2 h1=Q 9. Kxh1) (6...hxg3 7. Kxg3)

The classic example of this is a Richard Reti endgame study from 1921. (https://www.chess.com/forum/view/more-puzzles/the-reti-endgame-study is a link; it's the second study.)
The punch line is the white King has to take the diagonal path, essentially getting one square closer to catching the black pawn while at the same time getting one square closer to supporting the white pawn's promotion. The dual threat forces a draw.

I forget the exact details enough to be able to find it easily; but I think one of the Korchnoi - Karpov World Championship matches was lost because Korchnoi forgot something like Kd3-e4-f3 was possible (as opposed to Kd3-e3-f3).


text:
Why is Nd5 a blunder in this game?
I am surprised when Stockfish engine told me that nd5 is a blunder while suggests me to use my knight at f3 and take the pawn at e5. But, there is a black knight at c6 and if I do that, then, he will take my knight. In most strategies, it is best to exchange a weak piece for a stronger piece than for a player to exchange a strong piece for a weaker piece. It just doesn't make sense to me why.
I don't know how to format the moves properly, so I've posted the link here.
https://lichess.org/m21Of4sH/white
The reason that I moved my knight to d5 is because in that position, my knight is centered and could prepare for an attack if needed.

Forgive me, I don't know how to translate all of that into a readable format.

Which move are you talking about?

Nd5 basically does nothing in this position. It spends valuable development time on a move that attacks nothing and prepares nothing; it just gives Black a free hand to start doing something meaningful (like maybe ...d6, solidifying the center and preparing to bring his other Bishop into the game at either e6 or g4). The square d5 could make a good post for a knight, but only under two conditions: either because it can stay there long term or because it can use that square to accomplish something like getting to a long-term post on a better square or support an immediate attack. Pieces are strong and outposts are good not solely because of where they are but also because they either enable you to do something or prevent your opponent from doing something. Right now neither objective is in view; and if Black really wants to evict the knight, ...Nce7 begins an immediate sequence that will either drive it away (..c6) or exchange it, whichever Black chooses. Since you have no chance at all of maintaining that outpost, why waste the time to occupy it?
The engine suggests Nxe5 because of the "fork trick," a tactical sequence (...NxN 5. d4) which destroys Black's pawn center, and typically leaves a weakly placed piece in its stead (5. ... Bd6 6. PxN BxP and if White cares at all about it a well-timed f4 will force the bishop to seek some other place of worship).
The resulting position isn't lost for Black, by any means, but it certainly leaves Black worse off than before. It's advantageous enough that I check out Nxe5 whenever I see a Black knight on c6 and bishop on c5. It's one of those tools that should be in every chess player's toolbox; a quick way to gain a small advantage without even thinking hard.
When you only have two knights developed, the only attacks that can hope to succeed are against weaknesses your opponent has created. In this case, the only weakness Black has created is the potential to decoy the knight into a pawn fork; and that's not a serious weakness -- the resulting combination does not gain material, and only slightly improves White's advantage.
FWIW, I'm not all that fond of the engine's suggested response (...Nf6). I mean it does completely eliminate any plans you might have had for the Nd5 but I'm not sure exchanging it in that way results in anything other than developing the queen early, though it does have the advantage of speed. The main thought to take away from it is this: any threat you make that can be parried easily and quickly without forcing the creation of further weaknesses is probably not worth making.

I think the idea is that after Nxe5, you have d4 which attacks both the bishop on c5 and the knight on e5. Once you take one of his pieces, you might be a little ahead on development in the opening.
Whereas if you move your knight to d5, you are moving a minor piece twice in the opening at the expense of developing your other pieces. And it won't be much useful for an attack at this stage because your opponent could easily force it back or offer an exchange. In fact, after you move d5, Stockfish suggests Nf6 and an exchange of knights, leaving your opponent's queen developed and gaining a tempo.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Is there a mathematical theorem that you can use to win a chess endgame?
Have mathematicians created any theorem that determines the outcome of a endgame? If so, how could it be used to win a specific endgame?

Unfortunately the (original) question was a bit ambiguous and arguably still is. I try to sort the different interpretations out:

Chess fulfils all requirements of "standard" game theory (zero-sum, two players, full information, no chance). This is your main theorem. Thus Chess could be solved principially - "just" create a 32 piece tablebase :-) In praxis, this of course is hopeless, cf. Allure's points. At the moment (2021), Chess is completely solved for 7 piece endgames, 8 is the next goal and in the works.
OK, assume you meant "solve some specific given position" instead. In this case, an unconditional "yes". For only one example, look up Noam Elkies' work on simple pawn endings (although identical results can be obtained with classical chess analysis - arguably it looks more elegant in Conway notation instead - at least to a mathematician).

"Just" create a 32 piece tablebase? Is it possible to create a complete, finite move tree for chess? There could be infinite looping between various positions if neither player claimed a stalemate by the fifty move rule, couldn't there?

If there is a finite tree of all the legal moves then yes, there is a theorem about how to win any chess game: "just" build the tree and prune back from all the leaves that don't result in a win.

@ChristopherHamkins Yes. First, 75 move rule is mandatory so the game is not infinite. Besides, even if you ditch that rule so you can force one of long checkmate sequences, number of possible board states is finite - so you require a loop for an endless game. But any repeat of a position trivially means draw as no move in a loop gets you any closer to the win or lose, so you can simply prune those loops to "draw", keeping tree size finite.

@ChristopherHamkins Creating the tree is problematic, there are supposedly 2*10^46 possible positions. So, about 1k-10k atoms of Earth per position. That said, despite this difficulty of listing moves, a proof of draw or any side winning is not impossible despite that - heck, it might be even possible to find a compact solution that proves "X moves to checkmate" for every possible white and black move (assuming perfect play from that point onward).

@ZizyArcher We're talking about math, not physics. Mathematically, it doesn't matter if there's more possible positions than atoms on the earth. It's about provability, not practicality.

We do not need to know all move sequences to solve chess , with backtracking we could (in principle) mark every of the about 10^43 legal positions , so mathematically chess is definitely solvable. Even the full tree of possible move sequences is finite because of the drawing rules , but we do not need it anyway.

Such a theorem doesn't exist.
The closest is the strategy-stealing argument that can be used to show that for many games, the second player does not have a winning strategy. The gist of the argument is that if the second player did have a winning strategy, then the first player can play a random move and then adopt that strategy. If the random move is never a disadvantage (e.g. in Hex) then the first player would have a winning strategy, thereby proving by contradiction that the second player cannot have a winning strategy and the first player always wins (or the game ends in a draw).
This argument does not work for chess because there are positions where you don't want to make a move since any move is fatally weakening (zugzwang).

It's widely believed that, if chess were solved to the extent that TicTacToe is, then a player playing white perfectly against a perfect black player, white would either be able to force a win or at least a draw, but no such thing has been proven yet. I do wonder if it's been proven that there is some sort of perfect <forced win / draw> for at least one of the sides, though.

Edit to my previous answer: it looks like the common opinion is that both players playing perfectly would be a draw. A perfect white player cannot force a win.

Your question is a bit ambiguous, so I will attempt to answer it in the manner I think you will find most useful.

Well the whole of chess / 9LX isn't solved, but there are endgame sort of 'theorems' in the sense that there are positions that are provably wins/draws and so if you know the theorems and their proofs, then theoretically you know how to win/draw those positions.

See the 1st 40 seconds of this video:
https://www.youtube.com/watch?v=mCsc24k-Q8M

Loophole: these are mathematical theorems in the sense that chess / 9LX is a mathematical game

Karsten Müller talks about something like this at timestamp 5:20 in an interview with chessbase india: Endgames are like pure maths in the sense that they are something to prove. In contrast, openings are like applied maths or statistics like 'which opening has a high/er draw rate?' or 'which opening leads to early queen trades (or reaches endgame early)?'

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
How is rating score calculated on Lichess?
I've recently lost to a 1500 player. My rating is about 1200. Ironically, he got 163 points. How is it possible for a 1500 player to gain more points on a lower-rated player? The system that Lichess uses to calculate rating scores is very confusing. How is it done?

Could be the opponent's rating was still provisional.

See: What rating system does Lichess use?, Why is there a question mark (?) next to a rating? from the official lichess FAQ.

do you have a link? even if provisional +163? come on

Without the link to player profiles and the game iteself, it is difficult to say for certain exactly what happened.
For one, Lichess starts new users with a rating of 1500.[1]
Even if your opponent didn't have a 1500 rating, as double-beep points out Lichess uses the Glicko-2 rating system[2] which explicitly tracks the player's rating, a rating deviation, and a rating volatility. The system views a player's rating from a stochastic perspective, as an interval not a single point value.[1]
The system will detect and provide a larger rating change in various circumstances including:

"exceptionally strong results after period of stability",[3] or
after a period of inactivity (it is less certain if rating is still accurate).

The Glicko-2 creator, Dr. Mark Glickman, provides the mathematical formulas for the system.[3,4]
As an example, consider this classical game on Lichess. At the time of the game, the player with the White pieces had only played 1 rapid game. The system seeded the player (White) with a 1500 rating but annotated it as 1500? to denote the provisional rating.
References:
[1] Chess Rating Systems, Lichess website.
[2] What rating system does Lichess use?, Lichess FAQ page.
[3] Example of the Glicko-2 System, ME Glickman, 30 Nov 2013.
[4] http://www.glicko.net/glicko.html, website by Mark E. Glickman.


text:
What is the best approach when an opponent's queen is in the center and all of their pieces are developed?
I have played several games where my opponent's queen is somehow placed in the center of the board. However, this type of aggressive move positions my king in a dangerous spot. I can't castle because the queen can work with a bishop and provoke a checkmate. My other pieces are vulnerable to an attack because of their early piece development. I keep getting check after check because my king is in the center. It forces me to use my other valuable pieces to defend my king. This will eventually result in allowing my opponent to break my defense and slowly take out my pieces or, even worse, force my pieces to retreat. What is the best approach when this type of situation is encountered?

Are there a few representative games you could post to illustrate the types of positions and gameplay you are referring to?

When this type of situation is encountered, you have already lost, so your best approach is to resign.

The best approach is to prevent it.  If you haven't castled, and your opponent's pieces are developed, you've already made several grave mistakes.
Post your game and we'll review it.
There are a number of openings that are known to result in good positions.  Do you know which one you play?
EDIT - @toby ok, for what you do, is learn how to play the Ruy Lopez and Queen's Gambit with white.  Learn the Grunfeld and Caro-Kann and play them when you have the black pieces.  These are well known and solid openings. They will prevent the situation in which you find yourself.

@Tony Ennis, I'm not sure where to find my game history. But, I think my question is pretty clear on what I want to know. Tell me what is the best aproach to prevent it.

@SecretAgentMan it's a question. the OP's question doesn't provide enough information to allow us to really help.

@SecretAgentMan, I've flagged his answer.

@TobyHarnish edited

@TonyEnnis no harm done.  (+1)

@TobyHarnish I'm not sure a flag is warranted but ok. I think Tony Harnish is just trying to get clarification (i.e. you edit question) so he can better answer you.


text:
Why does Stockfish evaluate Nd4 as an inaccuracy in this particular game?
Here is the position:
[FEN ""]
1. e4 d5 2. exd5 Qxd5 3. Nc3 Qe6 4. Be2 Nf6 5. Nf3 Ne4 6. Nd4 Qd5 7. nxd5

I have two knights here. One knight is being attacked by the knight at e4. My other knight is at c3. I moved my knight to d4 to attack his queen. The reason I did that is because he has to move either his queen or knight. If he move his knight, I take his queen; if he moves his queen, I take his knight. Surprisingly enough, he moved his queen to d5. So, I took his queen. Also, Stockfish wants me to castle. This unorthodox move puts my knight into a very dangerous spot. If he were to take my knight at c3, I would have to take his knight either with the pawn at b2 or the pawn at d2. His queen could also become a threat to my king if he pair his queen with a bishop.
I do not see why castling can be beneficial in this position. So, what is the advantages of castling here? And, why is 6. Nd4 an inaccuracy?
The game is also here:
https://lichess.org/FF4CHOWP/white#12

His queen is on a bad square getting in the way of both his bishops and the e pawn. So why do you want to move your perfectly well placed knight to force it to a better square? Castle, and if your opponent takes on c3 take back with a pawn opening a line to get your remaining bishop out. You are miles ahead in development on an open board - it should be enough to win.

The reason is because in the situation if Qb6 is played then you could lose the knight. But if you move the knight you will lose the game because Qf2# is checkmate. white moves Nb5 then black will play a6 receiving a knight or the game.

6...Qb6 7. Nxe4 preserves material balance, though.

@Allure I agree but in this time white only has the knight and bishop as developed pieces. But black has a queen and c8 bishop. Counting the points black has 12 points developed but white has just 6 points developed. Also having a queen in the center is very useful because of forks. The queen can easily win free pieces if white is not careful.

It seems more complicated than that however. 6...Qb6 7. Nxe4 Qxd4 (forced) 8. d3 leaves White with three developed pieces to Black's one, and White has moves like Be3 to develop with tempo further. That's superficially not much worse than 6. O-O. One does not usually count points for development either (it's why developing the queen early is not ideal; opponents can gain time attacking the queen). I think the OP is a pretty deep question, certainly not a simple missed tactic or forced material win.

I agree with Allure. The accepted answer is extremely shallow.


text:
What is the highest possible number of pawn captures in a game?
What is the highest number of pawn captures possible in a game?

Each side has 15 pieces that can be captured, for a total of 30 captures. But after the last pawn capture, there must be a pawn remaining on the board. Therefore, no more than 29 captures are possible.
29 pawn captures are possible through the following sequence. First, the knights are captured, followed by the rooks, bishops, queens, and lastly the pawns. Finally, Black's passed pawn can then go ahead promote to a queen. Then it can move in to get captured by White's remaining pawn in the 29th pawn capture of the game.
[FEN ""]

1. Nc3 Nc6 2. Nf3 Nf6 3. Nd5 Nd4 4. Ne5 Ne4 5. Nb6 Nb3 6. Ng6 Ng3 7. axb3 axb6 8. hxg3 hxg6 9. Ra5 Rh4 10. Rc5 Rf4 11. Rc6 Rf3 12. Rh5 Ra4 13. Rf5 Rc4 14. Rff6 Rcc3 15. bxc3 bxc6 16. gxf3 gxf6 17. Ba3 Ba6 18. Bh3 Bh6 19. Bd6 Bd3 20. exd3 exd6 21. Be6 Be3 22. dxe3 dxe6 23. Qa1 Qa8 24. Qa3 Qa6 25. Qc5 Qc4 26. bxc4 bxc5 27. d4 cxd4 28. c5 d3 29. cxd6 cxd6 30. cxd3 c5 31. d4 cxd4 32. cxd4 e5 33. dxe5 dxe5 34. f4 Ke7 35. fxe5 fxe5 36. f4 exf4 37. exf4 g5 38. Ke2 gxf4 39. g4 f5 40. gxf5 f3+ 41. Ke3 f2 42. Ke2 f1=Q+ 43. Ke3 Qe1+ 44. Kd3 Qe6 45. fxe6

Now I wonder what the fewest moves are . A friend found 38 move version

If the last remaining pawn additionally delivers checkmate, could that be considered a 30th capture?

@wberry Checkmate is not possible with KP v K (with the P remaining a P).

Is it not possible for the last pawn capture to be an actual "pawn takes pawn" capture instead of involving a queen? That would be a lot more elegant.

@ToddSewell It would be, I just couldn't find one.

@wberry : it won't be 30, because at least one other uncaptured piece needs to be on the board for a pawn to give checkmate.


text:
What's the strongest non-ML chess engine?
What's the current strongest Chess Engine built solely on heuristics, no neural networks or any kind of deep learning?

The strongest classical chess engine is probably Stockfish classical, i.e. Stockfish with its NNUE turned off. I say this because Stockfish was leagues ahead of all its CPU rivals before the NNUE revolution, and after the NNUE revolution very few people are still working on classical engines, so it's unlikely anyone caught Stockfish. In fact, if you look at CCRL (Computer Chess Rating Lists), no classical engine has caught Houdini (all the engines above it are either NN or NNUE based).

What's Houdini?

@theonlygusti a chess engine - https://www.cruxis.com/chess/houdini.htm. Do note Houdini is controversial, because it's allegedly a Stockfish clone.

So by saying no classical engine has caught Houdini, you are saying that Stockfish is the strongest classical engine

Houdini is currently the strongest classical chess engine, but it is just a weaker version of what pre-NN stockfish used to be?

@theonlygusti Stockfish classical is significantly stronger than Houdini, and no classical engine has caught Houdini, let alone Stockfish classical.

Houdini is arguably an older version of Stockfish classical, in particular Stockfish 8. The last version of Stockfish classical was somewhere after Stockfish 11 but before Stockfish 12.


text:
Is Nxd5 playable in the Italian Game: Two Knights Defense?
The following move is considered dubvious in lichess.org opennings explorer because of the sacrifice in f7:
[FEN "r1bqkb1r/ppp2ppp/2n2n2/3Pp1N1/2B5/8/PPPP1PPP/RNBQK2R b KQkq - 0 5"]

1... Nxd5 2. Nxf7 Kxf7 3. Qf3+ Ke6 4. Nc3 Ncb4

The following explanation is given:

5 ... Nxd5?!
Immediate recapture of the pawn sometimes thought dubious, at other times theory considers it quite playable. From a positional point of view it's not considered a good move due to the creation of open lines that White can now use to aggressively attack, and for this reason it's rarely played at master level. While modern computer analysis suggests that it may be theoretically playable, few doubt that 5...Na5 is a more practical choice in an over the board game.

While I use to refuse sac lines because I am a poor player, I feel confortable with white in this line. However lichess says it is playable.
How much playable it is? Can black preserve material not being checkmated with his king on the center and the open white position?

Black is not in danger of being mated, but still, in the "standard" variants, Black also loses the e-pawn, thus having only +1 material, a huge developmental disadvantage, and a king on the run. In my youth, I blitzed this opening with both sides and always won, but that was because I was the best player in my club. If you are willing to suffer, go forth. The Lichess percentage is atrocious (+50=20-30) but Stockfish is unimpressed playing Black.

What is White's best continuation, 6. Nxf7 or 6. d4?

My (nonexistent opening) memory says, 6.d4, by far - but noone ever plays that ;-) Also, neither the Stockfish value (+1 for both) nor the percentage (+33 =33 -33) for d4 agrees. But there are simply not enough games for meaningful stats.

It's playable in the sense that there is no known forced win, but the line Black has to thread to equality is a fine one. This is reflected by the opening eval, about +0.7 - +0.9 (see my answer to a different question here about how to interpret the opening eval).
It's possible Black can defend the position. Here's a game which Leela Chess Zero defends with Black, and here's another where Stockfish defends with Black. It's even possible Black wins, although this game 1) Black was clearly the stronger player and 2) the book line given to the engines after 5...Nxd5 is not the best continuation for White, hence the 0.00 opening eval.
Note computers, if left to their own devices, generally prefer 6. d4 to 6. Nxf7.


text:
How do I evaluate the value of every piece in Mathematical Chess?
This is Vietnamese Mathematical Chess—
http://cotoan.vnvista.com/rules-en.html
The board contains 11 ranks and 9 files. Each side has ten pieces, numbered from 0 to 9. The board initial layout is as displayed in the picture below—

Movements: Each piece (with the exception of 0 piece) can move in any direction (vertically, horizontally, or diagonally − forward or backward), the max number of squares a piece can move depends on the number of the piece.
For example, the piece with number 2 can move 1 or 2 empty squares, while the piece with number 9 can move from 1 to 9 empty squares—

Capture: To capture the opponent's piece, a player must have two pieces one next to another. Then use the numbers of the two pieces to make calculations. Allowed calculations are + (addition), - (subtraction), × (multiplication), ÷ (division), and modulus (division reminder).
Any results of the calculations can be used to apply to the capture. If a result contains two numbers, then remove the tens number (for example 8×7=56=>use 6). Use a suitable result to make the capture by taking the piece behind to capture the opponent's piece.
For example, one player have an 8 piece and 5 piece next to each other vertically. Calculation results from these 2 pieces are:
8+5=13 (take 3)
8-5=3
8×5=40 (take 0 - which is useless anyway)
8÷5=1 with 3 as remainder (take both 1 and 3)
The player can then use the 8 piece (the piece behind) to capture an opponent piece which is 1 or 3 squares away from the 5 piece (the piece in front), in the same the direction that 8->5 is.
The image below shows how the 1 piece and 2 piece standing next to each other can capture the opponent's pieces. If an opponent's piece is on one of those X squares, the player can capture it. The calculations that the capture is based on are: 1+2=3, 1×2=2, 1÷2=0 with 1 as remainder—

The 0 piece (the one with zero number) is like the King in Chess. When it is captured, the player loses the game.
Besides capturing the 0 piece, players can agree at a certain point to end a match (if the 0 piece is not captured before that point is reached). The point that one player gains is calculated by summing the numbers of the opponent's pieces that have been captured.
For example, if the players agree to set the match's ending point to 10. Then when a player captures the 5 and 6 piece, he wins the game (5+6=11 which is greater than 10). Or if a player captures the 0 piece then he also wins.
We all know that the aim of Chess is to checkmate the opponent's King, the aim of Go is to surround a larger total area of the board with one's stones than the opponent (count by scores). In Mathematical Chess, I think we must balance Chess and Go, the game−complexity is really high.
I want to evaluate every mathematical chess piece value. I'm studying Machine Learning, how can I continue with my idea? I need your help. This Chess-variant deserves much more research effort.

Note that in the modern ML (viz Alpha) piece values exist at most implicitly. That said "Learning the piece values for three chess variants" by Droste (google it) clearly is your friend.

I want to evaluate every mathematical chess piece value

Currently there are two chess engine models. In the first, the traditional one going back 50 years, the engine is programmed with the previously known chess piece values for use in positional evaluation. In the second, the AlphaZero model based on neural networks, the engine learns by playing against itself with perhaps a head start gained by putting in a large number of master games.
This suggests two possible approaches you could try.
The first obvious one is to program your own neural net to play Vietnamese Mathematical Chess and derive piece values from that once it reaches a certain level.
The second one relies on you having a very large database of Vietnamese mathematical chess games and using a statistical method called logistic regression. There is an interesting blog post by Rasmus Bååth in which he describes his efforts to derive from scratch the values of the chess pieces in the traditional game using logistic regression which you might find useful.
How successful Rasmus Bååth's approach was is open to some doubt. He got that a queen was worth 4x a pawn, however that may be a reflection of his data rather than his methods. The relative value he obtained for the other pieces does correspond to traditional values. So, evaluating the knight as "3" gives bishop as just over 3, rook as just over 5, queen as just under 9, but pawn as just over 2.

Create a computer program or engine for that variant, then you can try to find the optimal piece values or other engine parameters by using a parameter optimizer like this parameter optimizer.
I am the author of this optimizer.

How can I connect to you on Twitter?

I have no twitter.

Do you have fB?

I don't have fb too.

Does Github have the Chatting? If so, I hope to share more idea with you.

Yes github has discussion feature or you can just create an issue for first contact purposes. I would recommend you to go to this site https://github.com/ianfab/Fairy-Stockfish, create an issue and introduce your variant. Be sure to indicate the rules. Fairy-Stockfish is capable of creating a game variant if basic rules are already supported. If not some programmers there might get interested and would support your variant and implement it in stockfish so that you will have your engine that can play the game and be able to test it.

Let us continue this discussion in chat.

Thanks a rl lot

It seems that no one likes this Chess-variant–  https://github.com/ianfab/Fairy-Stockfish/discussions/462


text:
Why not e3 instead of e4 in Grunfeld Russian system?
In the position below White continues with e4 after, say, Black castles. grunfeld-defense:
[FEN ""]
[StartPly "10"]

1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Nf3 Bg7 5. Qb3 dxc4 6.Qxc4

Question: How about e3 instead? Is there an outright refutation, or is it just stylistic choice?
I know a couple of QGD lines where after years of practice, people have started to try apparently less aggressive strategies, say by playing e3 and planning for a future e4 rather than an immediate e4 (which makes the game more dynamic and allows quick counterplay). The results have been better with the "slow" moves.
A follow-up: Does the inclusion of Bf4 and then e3 change the evaluation?

After your position, the most played move (at least by two orders of magnitude) is 6... O-O so I will focus on it only.
The main takeaway is that 7. e4 forbids 7... b6 (controlling the a8-h1 diagonal), but 7. e3 doesn't and black takes advantage of it by playing 7... b6.
If you want some engine statistics, Stockfish 22050407 evaluates

e4 b6 as at least up 200 centipawns (+2) for white with best move e5, so most likely winning for white (WDL ratio ~950 white wins, ~50 draws, =0 black wins).
e3 b6 as 0 centipawns, but black has better play overall.

e4 a7 is better (slightly) for white, 7. e3 a7 is better (slightly) for black.

do you mean a6? I don't think black can play a7.

yes, a6 , typo sorry

Thanks, I am glad I asked this question because your answer gave a new perspective previously unknown to me. The idea of a Bishop on b7 had not crossed my mind. If you don't mind, a follow-up question. What if we insert Bf4 first, I mean after Qxc4 0-0 we play Bf4 and then, say, in response to c6 or Na6, we play e3. Does this change the evaluation (from an engine's as well as human point of view) much?

@BehnamEsmayli: Would interest me too. I'm one of the if-I-ever-develop-my-Bc1-it-desperately-misses-for-the-protection-of-b2 guys, and that even contrary to the old adage that Qxb2 is bad even if it's good :-) Here Qxb2 is a complete nonissue and the (temporarily?) incarceration of Bc1 might be relevant for the evaluation.


text:
What helps you choose the right opening?
What goes through the mind of a chess player in the opening? In particular, what helps you choose the right opening?
After learning how to move the pieces, after understanding how the game is divided into stages, and after finding that openings can provide a wide range of theoretical exercises, I come to ask myself some questions.
This question is part of a series of questions asked by players who have begun their study of chess, and have previously learned chess terms, and now seek knowledge of how great players think and how they make decisions on each move.
next >> Part-2

What helps you choose the right opening?

This splits up naturally in various ways. The first way is general versus specific:

What is the right opening for a specific opponent?
In general, what are the right openings for me?

If I am going to be playing an opponent who has games online then I will try and look at those openings to see what they play and, if I can, prepare for them appropriately.
For instance, 3 years ago I was going to have white against an opponent who didn't have many games online and the black games he did have were mainly against 1. e4, to which he always replied with the Sicilian, whereas I almost always open with 1. d4. As a lazy player, I like whenever possible to limit my opponent's choices to make my life easier. Many years ago when I was an e4 player I played the Grand Prix Attack against the Sicilian. This was very fashionable in the 80's but is unfashionable now. It is possible, even likely, that my opponent had never seen it before. On the morning before the game I spent a couple of hours updating myself with the latest theory and had a comfortable victory as, indeed, my opponent had no clue what the ideas are behind the opening.
What are the right openings for me depends on my time of life, my energy, my ambition, my available time.
Strangely in my youth I tried to play quiet, positional chess and to play classically (whatever that means), building up small advantages, fighting off my opponent's tactical ideas and then grind them down in the endgame. The Queen's Gambit was the ideal opening, I thought, to achieve what I wanted as white. With black I played the French against e4 and was happy to play the black side of a QGD against d4.
Then about 20 years ago I decided that I needed to improve my tactical play and that I should therefore switch to more tactical, double-edged openings. I started opening with e4. Against e5 I aimed for something like a Max Lange. I never had the guts to play the King's Gambit. Against the Sicilian either the Morra Gambit, if I just wanted to blow them away, or the Grand Prix Attack. Against the French I played a Winawer with an early Qg4, caveman stuff, etc. A lot of fun and certainly good for my tactics but the downside of this approach is that there is a lot of work involved.
Nowadays I am not prepared to9 spend so much time so I have changed my repertoire again to minimize the work needed. To that end I try and play openings which limit the opponent's choices and make my life easy. That means opening with d4 as white and playing some kind of London, either traditional or Jobava. As black against e4 I still like the French but also like the Black Lion. Against d4 or c4 I like the Dutch (from my period where I liked to play tactical openings) but with e6 on the first move to avoid gambit lines. If my opponent plays e4 on the second move I'm comfortable switching to a French.
An important concept is that of related openings. This can make it easy to transpose from one opening to another (Dutch to French) or to switch openings to ones with similar ideas. For instance as a Black Lion player I'm also learning the Modern as there can be move orders (early f4 from white) or opponents against which the Modern is more comfortable for me. Similarly as a London player I like to sometimes switch to the Trompowski.
Whatever openings you choose to learn the most important thing is to be comfortable with the kinds of positions that typically arise from those openings. If you like fast action and tactics then play openings which get the center open quickly with the pieces flying into action. If you like slow, maneuvering games then keep the center closed with a French, Modern, KID, Dutch.


text:
What practices do you recommend for handling openings and variations?
What practices do you recommend for handling openings and variations?
After learning how to move the pieces, after understanding how the game is divided into stages, and after finding that openings can provide a wide range of theoretical exercises, I come to ask myself some questions.
This question is part of a series of questions asked by players who have begun their study of chess, and have previously learned chess terms, and now seek knowledge of how great players think and how they make decisions on each move.
previous >> Part-1
next >> Part-3

What practices do you recommend for handling openings and variations?

First and foremost, play your repertoire. Once you've chosen which openings you are going to play then play them in every game. The more practice you get with your chosen openings in important games the faster you will learn.
Learn the ideas behind your chosen openings. What is white trying to do in this opening? What is black trying to do? If you are white then you are primarily trying to implement white's ideas but secondarily, and still very important, you are also trying to stop black from implementing their ideas.
Find YouTube channels that cover your openings and interesting games with your openings. Search out interesting videos on your openings and use them to become familiar with the ideas both tactical and positional in your chosen openings. Some good channels to explore are Saint Louis Chess Club, Hanging Pawns, GingerGM
The most powerful learning you can do is learning from your mistakes. Where you can, for games with longer time controls, record the moves and go over the games. In some tournaments there is an analysis room where you can go with your opponent after the game to share your thoughts. This is a first good practice if you can. Second, when you lose or go astray in the opening, check out the theory when you get home. Did you miss an important move or idea? Or did your opponent play a new move or idea? Try and analyse, taking your time and writing your ideas down. Finally, check the game with the computer and see what it says you got wrong. It is important that this is the last stage not the first. You will learn much more if you use your brain first and not the silicon brain.


text:
As regards the opponent's moves, what things do you usually pay more attention to in the openings?
As regards the opponent's moves, what things do you usually pay more attention to in the openings?
After learning how to move the pieces, after understanding how the game is divided into stages, and after finding that openings can provide a wide range of theoretical exercises, I come to ask myself some questions.
This question is part of a series of questions asked by players who have begun their study of chess, and have previously learned chess terms, and now seek knowledge of how great players think and how they make decisions on each move.
previous >> Part-2
next >> Part-4

I admit I wasn't sure what the OP is getting at when referring to "movements" in the real question. Guided by the (at present) one answer, I suppose the OP means to refer to the opponent's moves.

In the opening every time my opponent makes a move the first thing I ask myself is "Was I expecting that move?". In other words, did my opponent make one of the standard replies in that opening or did they play something different.
If they played a standard move then normally I reply almost immediately with the next standard move in the opening.
If they played a move I don't recognize then I ask myself what the idea is behind their move. Maybe they are making an immediate threat which I must counter. Or maybe they are playing a move order trick to try and get me into a line I don't want which is better for them.
If I don't see a problem for me with their move I then ask myself if it was just a mistake and can I punish it. It could allow me to play a tactic. It could allow me to achieve one of the goals of my chosen opening which normally they should stop (e.g. e5 for black in the Classical Dutch or e4 for white in the same opening). It could introduce a new weakness which I can try to exploit by departing from the normal moves of the opening.

Primarily how it influences your strategy.
Secondarily to discover their playstyle and skill level - eg. Are their movements intentional blocks to your strategy or accidental? Do they like a closed or open state? Are they happy to simplify or leave things complicated?


text:
What goes through the mind of a chess player in the middlegame?
What goes through the mind of a chess player in the middlegame?
After learning how to move the pieces, after understanding how the game is divided into stages, and after finding that openings can provide a wide range of theoretical exercises, I come to ask myself some questions.
This question is part of a series of questions asked by players who have begun their study of chess, and have previously learned chess terms, and now seek knowledge of how great players think and how they make decisions on each move.
previous >> Part-3
next >> Part-5

The middlegame arises out of the opening and so in the early middlegame the ideas arise out of the opening chosen. For instance, the King's Gambit has the idea of opening the center quickly, allowing white rapid development and an early kingside attack often targeting the naturally weak f7 square. A hypermodern opening like the Modern has the idea of avoiding occupying the center with pawns. Instead it tries to exert control over the center with pieces. At the same time it looks to encourage white to over extend creating the possibility of a counter attack.
So, in the early middlegame the thoughts mostly center around the best moves to make to further these opening related plans. For a tactical opening these plans will be tactical and for more positional openings they will concern the creation of weaknesses in the opponent's position which can be exploited later.
In the late middlegame the emphasis changes. After the middlegame comes the endgame and it becomes more important to start thinking how to transition to a favourable endgame. For example, if you would have a much better endgame then it can make sense to force the exchange of queens, or if that's not possible, give your opponent every opportunity to exchange queens. Conversely, if you would be at a disadvantage in the endgame then try and keep queens on and try and create complex positions where it is easy to go wrong.
Throughout the middlegame, from early to late, it is important to bear in mind that tactics often play a key role in deciding the game and the middlegame is usually the area of the game with the most tactical possibilities. Hence it is important to have a checklist of questions to ask yourself before moving, like:

What checks do I have?
What threats do I have?
What threats does my opponent have?
What weaknesses does my opponent have that I may be able to exploit?
What weaknesses do I have that my opponent might be able to exploit?

All of these questions will require some calculation of variations to answer in full. So, two further rules are useful:

Calculate variations through to the end or even one move beyond because there is almost nothing worse than calculating a variation, playing it and discovering at the end that you missed your opponent's move which turns the position round.
Sometimes when you see a promising move, A, which you want to follow up with move B, it can be more effective to reverse the moves. Make sure you check both move orders.


text:
What goes through the mind of a chess player in the endgame?
What goes through the mind of a chess player in the endgame?
After learning how to move the pieces, after understanding how the game is divided into stages, and after finding that openings can provide a wide range of theoretical exercises, I come to ask myself some questions.
This question is part of a series of questions asked by players who have begun their study of chess, and have previously learned chess terms, and now seek knowledge of how great players think and how they make decisions on each move.
previous >> Part-4

A 9mm bullet, after I blundered away a win against GM Huschenbeth for the nth time. (Sorry, just kidding - normally I win any endgame :-) The normal answer thus is: How do I bring home the bacon (grand plan; split up into miniplans). There are too many types of endgames, thus a general answer would be moot.

The endgame is the part of the game which comes closest to being mathematically determined. In essence if there are 7 pieces or fewer left on the board then the result of the game with best play is known and can be looked up in the tablebases.
Further, there are many kinds of endgame positions with more than 7 pieces where it is clear to a player with the right "endgame knowledge" either which side is winning and the general process for winning the game or that the game should be drawn and what the drawing principles are for each side.
Ultimately there are different classes of positions with different algorithms for winning or drawing the game.
Consequently what goes through my mind are a series of linked questions:

Am I winning? (OK, it should really be "What is the evaluation here?" but I'm more self-interested than that)
If I am winning then do I know how to win? I can certainly know that I have a winning position with KNB vs K without knowing exactly how to win. If I don't know exactly how to win can I remember enough of the ideas and principles of the winning algorithm to realistically play for a win, to have a plan to keep me going.
If I am losing do I know enough about my opponent's winning algorithm to make it as difficult as possible for them to win? There are the 3-fold repetition rule and 50-move rule for me to aim for for my salvation.
If the game should be a draw do I know why and how I need to play to ensure the draw if I am on the weaker side and conversely what I need to trick my opponent into playing if I am on the weaker side?

There is a lot of knowledge of endgame structures and patterns involved here which is why at all levels of the game, from beginner to world champion, endgame study is a key component of maintaining and improving the level of play.

Hello Brian; i check that Rosie F edited all my question removing my format; removing the question from body/content and plase in title; that's right?

The traditional distinction between game stages is mostly academic in my opinion. I don't think the thought process of a chess player is radically different, except for the fact that you usually don't need to worry about king safety in the endgame, so players will consider moves and plans that use their king as an attacking piece.
When they exist, passed pawns become a major theme in the endgame since with fewer pieces on the board, it becomes more costly to dedicate one piece just to block it.
But other than the different strategic theme, the way in which we elaborate plans and calculate lines doesn't change that much


text:
Can you make a lucky brilliant move?
Is it possible to make a brilliancy (a brilliant move) with luck? Or is it so rare that it can only be spotted by the best chess players?

What is a brilliant move?

What are you trying to ask here? Is what so rare? Of course, it's possible to play a move which is good, without understanding the reason why the move is good. And "bad" players can also sometimes find and understand "good" moves.

chess.com's automated analysis has done so much damage

Is it possible to make a brilliancy (a brilliant move) with luck?

Absolutely.
For adventurous players I think it is not that uncommon. They often make risky moves which they haven't calculated all the way through. Sometimes they work and sometimes they don't. Tal played a lot of brilliant moves which later were found to be unsound but his opponent's couldn't find the refutation over the board. Tal was lucky.
What happens at a lower level is you see what looks like a brilliant move and play it without calculating all the way through to the end. Several moves in your opponent makes a move you hadn't anticipated or seen which seems to refute your sacrifice. You break out into a sweat. You hunker down and start thinking hard trying to find a way out. After 10 or 15 minutes you find the right move and play it. A few moves later your opponent resigns.
Your original move was a brilliancy which you didn't have the ability or patience to calculate all the way through. If you had calculated a little bit further you would have found your opponent's apparent refutation and given up. You were lucky you didn't calculate that far and then you were lucky again when there was a good reply that kept your attack going after your opponent found the tricky move.

So true. Here is a very recent example by myself: r1r2nk1/pb2qp2/1p2p1pp/2p1N2B/3P4/P3Q3/1PP2PPP/3RR1K1 w - - 0 18 1.Dxh6!! Dh4! Upsie. Hadn't even seen it. In the main line, I don't get my piece back and still am better by computer evaluation, as the black king loses all protection (2. Ng4!). (I played differently, the game ended in complete mayhem and a draw.)

Yes. The proof is trivial.  For any chess position where a legal "brilliant"1 move exists, then by definition there are at least n >= 1 legal moves. Then even if a player randomly selects a move legal in such a position, there exists the possibility of playing a "brilliant" move.
In cases where a player is not playing random moves, the possibility still exists, though it may be with a low probability.
YouTube videos from chess Twitch streams abound with content where a lower rated player plays an incredibly strong move without knowing why it is so strong, or where a lower rated player plays a move not realizing they checkmate their opponent. Similarly, though maybe less often, strong players may play a move believing it is strong not realizing it leads to disaster.
1. The question is unclear on the definition for a "brilliant" move but the answer holds for any definition that is also a legal move.


text:
Achieving e4 pawn push after 1.d4 opening
Is there a reasonable way for me to start with 1.d4 and be able to push (without gambitting) the e-pawn to e4. I am happy to do this without playing c4 first, and also it is ok if I get this pawn exchanged with Black's d-pawn (or f-pawn) as long as I get a piece (say the knight from c3) to recapture on e4.
Basically, I want my pawn on d4 and my knight on e4.
Is there any logical move order to (almost) force this?
Why is it somehow easier to do this with e and d switched: push 1.e4, 2.Nf3, then push d4.

the reason I don’t want 1.e4 version is that I want to end up with a pawn on d4 rather than on e4.
1.d4 d5 2.Nc3 Nf6 and now I have neither c4 nor e4 pushes. I like the look of this opening but with White I get nothing or even am often worse.

1.d4 d5 2.Nc3 Nf6 3.Bg5!

3 ... Nbd7 and black is at least equal - The stats on the Lichess master's database have white winning 26%, draws 37% and black winning 37%. Chess is a two player game - if black really wants to stop your plan you will have to find another way of furthering your evil intentions, and that is by exploiting the downside of whatever black has played. No opening can be played with total disregard for the other side, even the London system.

@IanBush Agreed. It seems like there is no satisfactory way to achieve e4 after 1.d4 unless Black allows it. So, Scotch is for now an attractive option for me to achieve what I call ''a center with 1 pawn and one piece.''

@IanBush the games that make those stats arise contain many inaccurate moves by White. For example the most common continuation is 4.Nf3 (which deviates from the plan of pushing e4 entirely). 2.Nc3 Nf6 3.Bg5 may not be the most challenging opening White can play, but it's more complicated than finding one position where Black scores well and call it a day.

I haven't played or studied it myself, but White's aim in the Colle System is to play e4 after due preparation starting with 1. d4. Quoting Wikipedia:

The Colle System, also known as the Colle-Koltanowski System, is a chess opening system for White, popularized in the 1920s by the Belgian master Edgard Colle and further developed by George Koltanowski. Quoting Wikipedia:
The Colle is characterized by several moves. White's center pawns are developed to d4 and e3, the king's knight is developed to f3, the king's bishop is developed to d3, and the queen bishop's pawn (c-pawn) is developed to c3. Common continuations include development of the queen's knight to d2 (Nbd2) and kingside castling (0-0). A major theme of the Colle System is the ambition to play a well-timed e4, where the square is defended by the bishop at d3, the knight at d2 (following Nbd2), and possibly the rook at e1 (following 0-0 and Re1). Although sometimes described as a specific sequence of moves, the Colle System is not a fixed line of play, but rather a system for White where the moves may be permuted at the player's discretion. When a game opens with most or all of the above moves, to the exclusion of moves which typify other openings, the game may be described as "a Colle System".

Wanted to suggest the London system. The Colle is also working. He can't force E4 in the opening, so this best bet would be to go with the Colle or London system and play for the e3-e4 break in the middlegame

Thank you. It definitely meets the criteria. Never crossed my mind, as Colle has this negative connotations with it. But I will give it a try.

I love the colle system, its like the london but the plans feel more fluid, very nice for lower rated players

There is a standard opening which has your idea as one of the ideas of the opening. That is the Veresov opening. Basically white starts with the moves d4, Nc3, Bg5 and then at some stage the move Qd3 or the pawn move f3 prepares the e4 push.
Here is the 2014 game Nakamura - Karjakin where Nakamura achieved e4 followed by Nxe4 on move 10. Annotations are by YouTuber Kingscrusher. You can see his video covering this game here.
[Title "Nakamura - Karjakin, Baku 2014"]
[fen ""]
[Startply "19"]

1. d4 Nf6 2. Nc3 d5 3. Bg5 Nbd7 4. Qd3 (4. Nf3 g6 5. e3 Bg7 6. Bd3 O-O 7. O-O c5 8. Re1 b6 9. e4) 4... c5 (4... c6) 5. O-O-O (5. dxc5 e6 6. O-O-O Qc7 7. Nh3 a6 8. Kb1 Bxc5) (5. Bxf6 Nxf6 6. dxc5 e6 7. e4 Nxe4 8. Nxe4 dxe4 9. Qxe4 Bxc5 10. Bb5+ Bd7 (10... Kf8) 11. O-O-O) 5... c4 6. Qg3 (6. Qf3 e6 (6... Qa5 7. e4 Nxe4) 7. e4) 6... Qa5 (6... a6 7. e4 b5 8. Nxd5 Nxd5 9. exd5) (6... e6 7. Nb5 h6 8. Nc7+ Ke7 9. Qa3+) 7. e4 (7. Nf3 b5 8. e3 b4 9. Ne2 Ne4 10. Qh3 Qxa2) 7... b5 (7... dxe4 8. Bxc4) (7... e6 8. exd5 exd5 (8... Nxd5 9. Nxd5 Qxd5 10. Kb1) 9. Re1+ Be7 10. Bxf6 Nxf6 11. Qxg7) 8. Kb1 (8. exd5 b4 9. Nb1 (9. Nce2 Qxa2) 9... Qxa2 10. Nf3 c3 11. bxc3 Ne4 12. Qf4 bxc3) (8. Nxd5 Nxd5 9. exd5 Qxa2) 8... dxe4 (8... Nxe4 9. Nxe4 dxe4 10. Ne2 b4) (8... e6 9. exd5 b4 10. dxe6 fxe6 11. Re1 bxc3 12. Rxe6+ Kd8 13. Bxc4) 9. Bxf6 gxf6 (9...exf6 10. Nd5 (10. Nxe4 Be7 (10... Bb7 11. Nc3)) 10... Rb8 11. f3 exf3 12. Nxf3 Bb7 13. Nf4) (9... Nxf6 10. Qe5 Ng4 11. Qxe4 Rb8) 10. Nxe4 (10. Nd5 Rb8 11. Nc7+ Kd8 12. Nd5 Bb7) 10... Bb7 11. Nc5 (11. Nc3 b4) (11. d5 Bxd5 12. Rxd5 (12. Qe3 Bxe4 13. Qxe4 Rc8 14. Ne2 Qb6 15. g3 e6 16. Bg2 b4 17. Nd4 Nc5 18. Qe2 Na4 19. Qg4 Nc3+ 20. bxc3 bxc3+ 21. Nb3 Bh6) 12... Qe1+) (11. f3 Rc8) 11... Nxc5 (11... Bc6) 12. dxc5 Rc8 (12... e6 13. Nh3 Bxc5 14. Qg7 Rf8 15. Nf4) 13. Be2 (13. Nf3 Rxc5 14. Be2 Qc7) 13... Qc7 14. Qh3 (14. f4 Qxc5 15. Nf3) 14... Bg7 (14... Qxc5 15. Qd7#) 15. Bf3 Bxf3 16. Nxf3 e6 (16... O-O 17. Rd7 (17. Nd4) 17... Qxc5) 17. Rhe1 O-O 18. Rd4 Qxc5 19. Rg4 Rfd8 (19... c3 20. Qh6) (19...Kh8) (19... f5 20. Rg3 Kh8) 20. Qh6 Qf8 21. Qxf6 Kh8 22. Qf4 Rd5 (22... Qb4 23. Rxg7 Qxe1+ 24. Nxe1 Rd1+ 25. Qc1 Rxc1+ 26. Kxc1 Kxg7) 23. Ng5 Rf5 24. Qe3 Rd8 25. Rh4 (25. Re4 c3 26. bxc3 Qa3 27. c4 Qb2#) 25... Kg8 26. Rg4 (26. Rxh7 Rxg5 (26... Re5 27. Qc1 Rxg5 28. Qxg5 Kxh7)) (26. Nxh7 Qb4 27. c3 Qa4 (27... Bxc3 28. Qxc3) 28. Rc1 b4 29. Rxc4 (29. cxb4 Qxb4 30. Qe2 Rd2) 29... Kxh7) 26... h5 27. Re4 (27. Rg3 Re5 28. Qc1 Rxe1 29. Qxe1 Qb4 30. c3 (30. Qxb4 Rd1#) (30. Qc1 Rd1 31. c3 Qd6) 30... Qa4 31. Kc1 Qxa2 32. Nf3 Qa1+ 33. Kc2 Qa4+ 34. Kc1 b4) 27... Qb4 (27... Rfd5 28. Rc1 c3 29. bxc3 Rc8) 28. c3 (28. Qc1 Rxg5 29. c3 Qc5) (28. b3 Rfd5 29. c3 Bxc3) 28... Bxc3 29. Qxc3 Qxc3 30. bxc3 Rxg5 31. g3 Kg7 32. Kc2 Rd3 33. f4 (33. h4 Rf5 34. f4 Rxg3) 33... Rgd5 34. R1e2 Kf6 35. a4 (35. a3 h4 36. gxh4 Rf3 37. Rd4 Rxd4 38. cxd4 Rxf4 (38... Rxa3)) 35... a6 36. Rf2 Kf5 37. Re5+ Rxe5 38. fxe5+ Kg6 (38... Kxe5 39. Rxf7 h4) 39. a5 (39. Rf6+ Kg7 40. Rf2 Re3) 39... Rd5 40. Re2 Kf5 41. Rf2+ Kg6 (41... Kxe5 42. Rxf7 Ke4 43. Ra7) 42. Re2 Rd3 43. Re4 Rf3 44. Rd4 Rf2+ 45. Kb1 Rxh2 46. Rd6 Rg2 47. Rxa6 Rxg3 48. Kb2 b4 49. cxb4 (49. Rb6 Rg2+ 50. Kb1 h4 51. Rxb4 h3 52. Rb2) 49... Rb3+ 50. Ka2 Rxb4 51. Ka3 Rb5 52. Ka4 Rc5 53. Rb6 (53. Kb4 c3 54. Kxc5 c2) 53... c3 54. Rb1 c2 55. Rc1 h4 56. a6 h3 57. a7 Rc8 58. Kb5 h2 59. Kb6 Rh8 (59... Kf5 60. Rxc2 Rxc2 (60... h1=Q 61. Rxc8) 61. a8=Q) 60. Rh1 Kf5 0-1

I have attempted such openings by white. This is often what happens: White's play is just weird and clumsy. Unless Black is completely passive, he/she can find faster counter offensives, as happened in the game.


text:
Largest round robin ever?
First, I myself played several large (20+) blitz round robins, this is nothing unusual. Thus: only "long" games.
Second, oversize round robins were quite common in the good old days (maybe as a gentleman you had enough domestics to do the work?), so a record might lurk there. (Didn't find it in the linked list, but you can use it to establish "34" is to beat. Because Gustav Neumann won all his 34 games. This should imply it was a round robin, BTW, although I'm not 100% sure.)

What is the criterium for 'largest':  the most players, or the number of rounds?

The '34' is from a club tourney, where the conditions was that every player should
play two games with every other player.  However, a player was only required to
appear in the club once a week, and then play at least one game. (Neue Berliner Schachzeitung, v. 2 (1865), p. 117) At least 22 players entered, but needless to say, many players dropped out quite quickly.

@user30536: THX for the info, I couldn't fact-check that detail first, naturally. And "most number of rounds". Ideally both are equal. (Somewhen someone will ask "most number of games"...)

As for being equal: Some older candidate RR tournaments have just five players, but each player played four or five games with every other player RR (could be argued to be a match tournament,, though). While tournaments like Palma de Mallorca, 1970 have 24 players single RR, London 1883 had 14 players, double RR, but special rules for draws, so crosstables for this show more games than expected. I suspect an answer will come from someone with access to di Felice's collection of tournament crosstables -- my own lists are very dated.

For the sheer record that would count as contender. :-)


text:
Playing against a tablebase online
I'm looking for a website where I can play endgames against a 6-man or 7-man tablebase. These tablebases are too large for me to install locally. I'm aware that Lichess allows users to view tablebase result. However, I'm trying to practice endgames against the tablebase without looking up the moves and entering them myself, like in the Browne vs. BELLE match. Lichess's engines currently don't use the tablebases when they play against users.
Does anyone know an existing website that would allow me to do this?

You can query the Syzygy tablebases here, and if you cover up what the tablebase tells you to do, you can "play" against it. Every time it's the tablebase's turn to move, pick the move that it lists at the top.

Seems to be the best option for now, I'll keep searching for a site that allows the best responses to be played automatically.


text:
Winboard: how can I search for a player name in loaded pgn files
I have loaded into Winboard 32 GUI this 8GB file: https://drive.google.com/open?id=1F8QWIkjhrOJdqkNrlN19nnWQpeww-2mv
How can I do advanced search for players names, place ELO etc. ?


text:
Fritz 18 Position Setup For Engine Match
The other day, I saw a GothamChess on two engines playing the King's Gambit. I thought to myself that it would be interesting to do the same thing, so I tried it in Fritz 18. I know that I have to store a position in a database define the database that I want them to play in the openings tab, but I don't know how to do so. If I try, then the engines simply play from the starting position instead of playing from the selected position. Am I doing anything wrong? Please help.


text:
Why did I lose -> I thought I can swap king and castle to avoid checkmate?
[FEN "6nN/Bp1k2pp/2n5/p7/Q4R1P/5pP1/P3qN2/4K2R w K - 0 1"]

As you can see my king got checkmated through the enemy's queen and pawn.
My question is, why is this a checkmate? I haven't moved the king as well as the castle to the right.
Why can't I swap them, so King=g1 & castle=f1, saving the king and evading checkmate?

Sorry, this one might be better

According to the FIDE Laws of Chess:

3.8.2.2    Castling is prevented temporarily:

If the square on which the king stands, or the square which it must cross, or the square which it is to occupy, is attacked by one or more of the opponent's pieces

So, there are two reasons why you may not castle:

You are in check
Your king would need to pass over the square f1 which is attacked by the enemy queen


text:
Comparing evaluation from position after white move to position after black move?
I'm coding a chess engine and have the following problem:
I want to only evaluate if the position is quiet, meaning if one side takes a piece the depth should grow by one ply. If then the other party takes on the same field it should grow by another ply. Unfortunately it was not possible to compare the evaluations of the positions of one move of the black side to the evaluation after a white move, because that makes one party much better than the other.
That brought me to the following beta solution:
If a party doesn't take a piece at the last regular searched ply, the depth won't grow any deeper. If a party takes a piece at the last regular searched ply, the depth grows by two ply to compare the board after two more moves. When a party takes, the opponent takes back and the party takes again, the depth rises by another two ply. However this method causes a lot of nearly useless move calculation, as I have to research all moves for the opponent for a certain move of the first party that takes a piece, only to know if it takes back. And for all the cases it doesn't take back this calculation seems useless, as I only evaluate the position after the move before the opponents.
Is there a way to either use the precalculated ply from an opponent to improve the evaluation or to waive that precalculation cmpletely?

I think what you are looking for is a Quiescence search, a search that only looks at capture moves, and is in place of a static evaluation once depth reaches 0 in your initial search. Check out this chessprogrammingwiki article: https://www.chessprogramming.org/Quiescence_Search


text:
Why is Qe7 a blunder here?
I'm a chess beginner. I played this game against Stockfish and according to Lichess' analysis, Qe7 was a blunder here, and the best move actually was c6. I can't understand why?
[Title "Why is Qe7 a blunder?"]
[fen "r1bqkb1r/pppp1ppp/5n2/8/2Q1P3/2N2N2/PPP2PPP/R1B1K2R b KQkq - 0 1"]

1... Qe7? (1...c6)

Qe7 is a blunder for a number of reasons:

It blocks your f8 bishop
When you are already behind in development and having given up the center it does nothing for your development and does not fight for control of the center
It gives away the c7 pawn
It does not threaten to win the e4 pawn. If you do try and take it it will be very bad for you with your king and queen lined up on an open file and white's rook coming quickly to e1.

Here is what could happen:
[Title "Qe7"]
[fen "r1bqkb1r/pppp1ppp/5n2/8/2Q1P3/2N2N2/PPP2PPP/R1B1K2R b KQkq - 0 1"]

1... Qe7 2. Qxc7 Nxe4 3. O-O Nxc3 4. Qxc3 d5 5. Re1 Be6 6. Bf4 Rc8 (6...Qc5 7. Qe5) 7. Qd2

In both cases white has castled and completed development apart from the a1 rook. Meanwhile black's king is stuck in the center with an open center.
c7, on the other hand, protects the c pawn, stops the white knight from coming to b5 and lays the groundwork some time in the future for a possible d5 to contest the center.
Yes, after c7 the pawn push e5 looks scary but fortunately there is d5 for black and after white moves the queen there is a safe square for the f6 knight on d7.
[Title "c7"]
[fen "r1bqkb1r/pppp1ppp/5n2/8/2Q1P3/2N2N2/PPP2PPP/R1B1K2R b KQkq - 0 1"]

1... c6 2. e5? (2. Bg5 d6 3. O-O-O Be6) d5!

And white is better but black is still in the game.

Qe7 is a blunder because after Bg5! Black is lost.Stockfish played Bg5 right?


text:
How good is Ding Liren in xiangqi (Chinese chess)?
Just wonder, what is the level of Ding Liren in Chinese chess (xiangqi)?

Where have you already looked for information about this topic ? Do you have any source about Ding playing Xiangqi at all ?

According to wikipedia he was Chinese champion in Chinese Chess: https://en.wikipedia.org/wiki/Chinese_Chess_Championship

That is the Chinese "Chess Championship", not the Chinese "Chinese Chess" Championship.


text:
Why is Nh6 a mistake here? Why is Nf6 the best move?
I'm analyzing this game between me and Stockfish Level 1 on lichess.org: https://lichess.org/0SvUBEu0/black#4

With Nh6 I was trying to counter a possible Bxf7+. Without Nh6, the King would have to move making castling impossible.
On the other hand, what is Nf6 supposed to do? Nf6 is the engine recommended move here.

You do realise that Bxf7+ loses the Bishop anyway?

In the opening it is recommended that you develop you pieces towards the center, especially the knights which are much more active there than on the edge. So 2...Nf6! is better than 2...Nh6?
Notice that the knight on h6 cannot go anywhere but back to g8: g4 is controlled by the Qd1 and f5 by the Pe4. True, you protect f7, but that pawn is already protected by the king (3.Bxf7?? is bad in any case because of 3...Kxf7).
Moreover the Nh6 will soon be attacked by the Bc1 (after d2-d3 or d2-d4) and an exchange on h6 would spoil your pawn structure after you take back with ...gxh6. It becomes quite risky to castle short because the isolated doubled pawns on the h-file are not a good shelter for your king.
On the other hand, from f6 the knight attacks the Pe4, controls d5 (to prevent White from using that square, or to push d7-d5 later), will be a good defender of your king after you castle. It also stops White from reinforcing the attack against f7 (no Qh5, and Qf3 is blocked from eyeing f7) if that's what worried you.
All in all, 2...Nf6 is a much better move than 2...Nh6.

"Moreover the Nh6 will soon be attacked by the Bc1 (after d2-d3 or d2-d4) and an exchange on h6 would spoil your pawn structure after you take back with ...gxh6.".I think this kind of advice is not really helpful for beginners.You need to seek tradeoffs when your opponent doubles ur pawns because the doubled pawns are also isolated pawns most of the time , so they are a even bigger weakness in a endgame.

@Cerise : I am not sure what you mean. The damage kingside structure is an issue for Black both in the middlegame (weak king) and in the endgame (weak pawns), so Black should try to avoid it altogether.

Black isnt forced to castle.You dont castle by default.Sometimes it is better not to castle.Back can also castle queenside.

B:f7 is not a threat at this moment since white pieces have no way to join the attack immediately and the black King can safely retreat.
Thus the best strategy is to developed pieces actively. The move Nf6 is ideal for various reasons including the fact that it controls the squares g4 and h5 which are the natural squares the white Queen could use to attack the King.
Also, the Knight on f6 supports a future d5 push by black which can be a natural plan. Remember: one of the basic goals of an opening is to exert a control of the central squares.

Control of the center.If you control the central squares(d4,d5,e4,e5) then you have more pressure than your opponent and can infiltrate his/her camp.Control of the center is important because any pieces or pawns in e4,e5,d4,d5 can restrict your opponent's moves very much.

In a nutshell, castling is good but it's peanuts compared to being up a piece. White isn't going to play Bxf7+ no matter what you do, so do something more useful with your move instead.


text:
Why is Nf6 a blunder here?

With Nf6, I'm trying to bring my Knight out. If the Bishop takes it, I can take the Bishop with by g7 pawn. Why is this a blunder?

Because after Bxf6 gxf6 there is Qxf6, which wins a pawn, threatens the rook and threatens mate on f7. You can castle, but then the king is exposed by the missing g pawn. Your only other option is Rf8.


text:
Every longbow-wielding peasant's finest hour?
It's called the English opening - some reference to Howard Staunton and the perambulations of the mid to late 19th Century; but, does the variant name refer to the Ancien Regime charging up a muddy hill, or the propensity to loose masses of arrows then get stuck in with the sword and shield after?
[Title "English Opening: Agincourt Defense"]
[fen ""]
[Event "Rated Bullet game"]
[Site "https://lichess.org/AeUmXNuE"]
[Date "2023.09.15"]
[White "heallan"]
[Black "bsalman"]
[Result "1-0"]
[UTCDate "2023.09.15"]
[UTCTime "00:22:41"]
[WhiteElo "1381"]
[BlackElo "1446"]
[WhiteRatingDiff "+6"]
[BlackRatingDiff "-6"]
[Variant "Standard"]
[TimeControl "120+0"]
[ECO "A13"]
[Opening "English Opening: Agincourt Defense"]
[Termination "Normal"]

1. Nf3 e6 2. c4 d5 3. cxd5 exd5 4. d4 Be6 5. Nbd2 Bb4 6. a3 Bxd2+ 7. Bxd2 Nf6 8. e3 Ne4 9. Ne5 Nxd2 10. Qxd2 O-O 11. Bd3 Nc6 12. Nxc6 bxc6 13. Qe2 g6 14. Qf3 Qd7 15. Rc1 Bf5 16. Bxf5 Qxf5 17. Qxf5 gxf5 18. O-O Kh8 19. Rxc6 Rac8 20. b4 Rg8 21. Rfc1 Rg7 22. Rxc7 Rcg8 23. g3 h5 24. Rxa7 h4 25. Rcc7 hxg3 26. fxg3 Re8 27. Rxf7 Rxf7 28. Rxf7 Rxe3 29. Rf8+ Kg7 30. Rxf5 Rxa3 31. Rxd5 Ra4 32. Rb5 Kf7 33. d5 Ke7 34. Rb6 Kd7 35. d6 Ra1+ 36. Kg2 Ra2+ 37. Kh3 Rd2 38. Rb7+ Kxd6 39. Rb6+ Kc7 40. Rb5 Kc6 41. Rg5 Rd4 42. Rg4 Rd5 43. Rg6+ Kb5 44. Rg4 Rh5+ 45. Kg2 Rf5 46. h4 Rh5 47. Rg5+ Rxg5 48. hxg5 Kxb4 49. g6 Kc5 50. g7 Kd6 51. g8=Q Ke7 52. Qg4 Kf6 53. Qf4+ Ke6 54. g4 Kd5 55. g5 Ke6 56. g6 Ke7 57. g7 Ke6 58. g8=Q+ Kd7 59. Qf6 Kc7 60. Qgg7+ Kc8 61. Qff8# 1-0

So, why is this response to the English Opening called the Agincourt Defense?
2k2Q2/6Q1/8/8/8/8/6K1/8 b - - 6 61

does the variant name refer to the Dukes of Burgundy charging up a muddy hill, or the propensity to loose masses of arrows then get stuck in with the sword and shield after?

Alas, no. It is more prosaic. At Agincourt the French faced the English and here white plays c4, the English, and black responds with e6 and d5, the French. So, we have the French against the English.


text:
Difficulty with magic bitboards
I am having some difficulty with magic bitboards, in that multiple blocker bitboards which would result in different attack boards having the same index. I realize this is likely because of one of the following reasons:

The magics I am using are incorrect.

I am generating indexes incorrectly.

I am generating attack masks incorrectly.

I have tested my code relating to problems 2), and 3), finding it to be correct, as well as trying different sets of magics, however this has not worked. I would greatly appreciate any help. I have attached the relevant code (C++17), or refer to a set of working magics.
// to generate the attack sets
for (int i = 0; i < 64; i++){
    int n = count1s(rookMasks[i]);
    for (int j = 0; j < 1 << n; j++){
        ull bb = int2blocker(j, rookMasks[i]);
        int ind = index(bb,rookMagics[i],rookShift[i]);
        ull attack = rookMask(i,1,bb);
        blockedRookMasks[i][ind] = attack;
    }
    n = count1s(bishopMasks[i]);
    for (int j = 0; j < n; j++){
        ull bb = int2blocker(j, bishopMasks[i]);
        int ind = index(bb,bishopMagics[i],bishopShift[i]);
        ull attack = bishopMask(i,1,bb);
        blockedBishopMasks[i][ind] = attack;
    }
}

The magics and shifts I am using come from here https://github.com/goutham/magic-bits/blob/master/include/magic_bits.hpp (lines 108-191)


text:
Unique checkmates count analysis
How many unique checkmates are there from this starting position?
I can only see 5 lines on lichess from a game I've played and have tried several different moves.
Mate in 4 is the fastest but I've seen up to 12. There must be at least 15 different mates, not all of them have the same ending position.
[Title "Black to move"]
[fen "8/p2rk3/1pQ1p1p1/2p5/1P2P3/2PP1n2/P2bq3/RK1R4 b - - 0 1"]

Practically infinite. Take the rook and trade off material, then keep shuffling your pieces indefinitely.

@shawn_xu there is still a limit to how long a chess game can go on, 50 moves without capture are considered to be a draw.

Still one side has to claim a draw before the game officially ends.

You're asking for the number of ending positions and not the number of first moves by Black that will lead to checkmate, right? If it's the number of ending positions, are we assuming White is cooperating with the final position? Like, 1...Bxc3 threatens Qb2# but White can choose to not defend the mate and play something weird like Rh1 just so the ending position is different than what you're aiming for (or to create a different ending position that you are aiming for.)


text:
Are Chess Engines Humanoid Figures?
On Youtube it shows chess engines as humanoid robots (here, for instance). Is this true, and if so do they play chess over the board according to their software? That would explain why they don't always play the best move according to their algorithm.

It's a valid question some people may have, my +1 against the -3.

@OverLordGoldDragon Thanks, I'm not sure what people think is wrong with my question. The least they could do is leave a comment or something.

Reasons to downvote a question: 'This question does not show any research effort, it is unclear, or not helpful'. I guess this question is unclear and doesn't show any research effort. Just google "what's a chess engine" and you're done. About clarity: other than the title, the rest of the question makes no sense at all: "That would explain why they don't always play the best move according to their algorithm." -> what does it even mean?

@emdio Stockfish (and other engines) doesn't always play the best move according to its own analysis after the game. I was wondering if this was because of the time during a live game. That is what I meant when I said that.

@gordon I have some experience at chess programming and chess engines just play the best move. But the best move depends (among others ) on the time used in the analysis, the hardware and the engine version. If you provide some examples of that "not playing always the best move" behaviour it could be an interesting question.

No, chess engines are not humanoid robots. That is just something that the YouTube channel uses to represent the engine so that the videos are more approachable for the intended audience. Chess engines are simply software that run on computers. People may make a robot or animated personality to go with the engine, but that would be entirely separate from the engine itself, and it would not change what the engine does.
Strictly speaking, a chess engine is just a piece of software that defines some criteria for differentiating between good and bad positions. When given a position to analyze, it will yield the best move according to this criteria. It takes time and resources to find this best move, so the same engine analyzing the same position with different amount of time or computer resources may yield different results. This would be especially noticeable when comparing to the performance of an engine that is playing a match, where time is limited, to the same engine analyzing a position after a match, where time is unlimited.


text:
Extremely slow move generation in chess engine
I am making my first chess engine in python (which is obviously not that fast). I am using the mailbox approach rather than bitboards, as switching would likely take more effort than just restarting the project. I use pseudo legal move generation, and currently my program can generate about 150k nodes per second (I can get 80 million nps on stockfish perft). Any tips other than switching to bitboards?

Err...don't use Python?


text:
How to use chessbase to find moves that produce "only winning sequences" if present?
A lot of times you may find yourself in a losing position, and with best play surely, you'll stay losing, but there is a possibility that you make a move which is not necessarily considered the best move according to the engine, but the response from the opponent turns out to be an "only winning line" or perhaps two.
Is there a feature in that program or any other program to find such moves?


text:
Are there any recent resources on this variation of the Exchange Caro-Kann?
The variation I'm talking about is:

e4 c6
d4 d5
exd5 cxd5
Bd3 Nc6
c3 g6!? .

[FEN ""]

1. e4 c6 2. d4 d5 3. exd5 cxd5 4. Bd3 Nc6 5. c3 g6!?

I found it in an old book about the Exchange Caro-Kann but it's written without ideas, only a list of moves and for me it's not so useful. In general, I've found out by viewing that list of moves that it could be a sort of system: Black wants ... Bg7, ... Nh6, ... f6 followed in the future by ... e5 if White allows it, but I tried playing it on lichess and my execution was really bad; so I'm interested in the opening and curious about resources.

Exchange Caro-Kann is mostly about black light squared bishop - it's his worst piece by far. So one important idea is how to exchange it off. In these g6 systems it's common to delay castling and play Bf5 - idea being that if white takes, you take back with g-pawn and you have kingside pressure through open g-file. Sometimes, if white played imprecisely enough, you can also afford to play e5 without f6, converting to isolani structure. There were some masterclasses on youtube about this, I will try to find them later.

i have faced similar to this https://lichess.org/bAxsVoXj#24

There is GM Neiksans bootcamp about exchange caro-kann: https://www.youtube.com/watch?v=pMGO2OOj33Y It's from white perspective, but he also explains ideas for black. Around 20minute mark he starts covering g6 systems, even though he uses a tad different move orders.

Interesting, I will check it out. Thanks.


text:
Are there any recent resources on this variation of the Two Knights Caro-Kann?
The variation I'm talking about is this:

e4 c6
Nc3 d5
Nf3 a6!?.

I'm interested in knowing some plans and ideas connected to the 3. ... a6!? move. I saw it originally in this game: https://www.365chess.com/game.php?gid=4237916.

I don't play the Caro-Kann, but from clicking around a bit, the idea seems to be to avoid 3...Bg4 4.h3 Bh5 5.exd5 cxd5 6.Bb5+
I don't know if there's much more to it.


text:
Are there any recent resources on the Keres Defense?
I am changing my Black repertoire, and became interested in the variation:

d4 e6
c4 Bb4+.

I wonder if there are any recent resources about this "Keres defense" to learn some plans and ideas.

You could enter the position into the free Lichess analysis board or another board of your choice to see what the engine recommends and also to see what top players played in the opening.
As for books, I believe this one to be good (it is called the Kangaroo defence here but it's the same opening).
It is expensive on the website I listed but you can probably find it cheaper elsewhere.


text:
Why is Ba4 an inaccuracy here? Why is Bd3 the best move?
I played this game recently as white: https://lichess.org/b7B16RLF/white#18
[FEN ""]

1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. Be3 Bxe3 6. fxe3 d6 7. d4 Bd7 8. Nc3 O-O 9. Qe2 a6 10. Ba4 h6 11. O-O-O Qe7 12. h3 b5 13. Bb3 Rab8 14. g4 h5 15. g5 Nh7 16. Rdg1 Ra8 17. Nd5 Qd8 18. Qg2 f6 19. gxf6 Nxf6 20. Qxg7# 1-0

On move 10 I played Ba4 to protect my Bishop from the attacking a file pawn while continuing to target the black knight on c6. But according to Stockfish, this is an inaccuracy and that the best move is Bd3.
I want to understand why.

If you follow the suggested virtual variants with an engine on, you can see the reason immediately.
If it still goes over your head: Your tactical instincts should scream danger. Your K and Q idle around on the e-file. Black will attack with exd4 and Re8. Now, only the e pawn is in the way of doom, and Black will win it, if necessary by Nxe4 and d5, or with b4, driving away the Nc3, also if necessary, N-a5xb3 (if Bb3 tries to protect d5, Black exchanges the last defender). It's a pretty straightforward case of pins and mobbing the weakest point.
Example variant: 10.Ba4 exd4 11.exd4 Re8 12.Bb3 Na5 13.O-O Bxb3 14.axb3 Nxe4! 15.Nxe4 d5.
In contrast, Bd3 overprotects e4 and gives you time to get your royal stuff out of the line of danger.

There's a "share and export" tab below the board, to the right, at that link, it has FEN and PGN.


text:
Why is h3 a mistake?
This is the 12th move of this game I played as white: https://lichess.org/b7B16RLF/white#22
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. Be3 { C65 Ruy Lopez: Berlin Defense, Kaufmann Variation } Bxe3 6. fxe3 d6 7. d4 Bd7 8. Nc3 O-O 9. Qe2 a6 10. Ba4?! { (0.06 → -0.77) Inaccuracy. Bd3 was best. } (10. Bd3) 10... h6?! { (-0.77 → -0.21) Inaccuracy. exd4 was best. } (10... exd4 11. exd4 Re8 12. Bb3 Na5 13. O-O b5 14. Qd2 b4 15. Nd5 Nxe4 16. Qxb4 c5 17. Qa3) 11. O-O-O Qe7?! { (-0.73 → 0.20) Inaccuracy. b5 was best. } (11... b5 12. Bb3) 12. h3? { (0.20 → -1.24) Mistake. d5 was best. } (12. d5 Nb8) 12... b5 13. Bb3 Rab8?! { (-1.27 → -0.46) Inaccuracy. Na5 was best. } (13... Na5) 14. g4 h5?? { (-0.22 → 3.88) Blunder. Na5 was best. } (14... Na5 15. dxe5 dxe5 16. Rhg1 b4 17. Nd5 Nxd5 18. exd5 e4 19. Nd4 Rb6 20. Kb1 Rd6 21. Bc4) 15. g5 Nh7 16. Rdg1?? { (3.87 → 0.90) Blunder. g6 was best. } (16. g6 Kh8 17. Bxf7 exd4 18. Nd5 Qxe4 19. Ng5 Qh4 20. Nxh7 Rxf7 21. gxf7 Kxh7 22. Rhg1 Bf5) 16... Ra8?? { (0.90 → 4.30) Blunder. g6 was best. } (16... g6) 17. Nd5 Qd8 18. Qg2?? { (4.35 → 1.82) Blunder. g6 was best. } (18. g6 Kh8 19. gxh7 g6 20. Qd2 Rb8 21. dxe5 dxe5 22. Qc3 b4 23. Qd3 Rb5 24. c4 Rc5) 18... f6?? { (1.82 → Mate in 2) Checkmate is now unavoidable. g6 was best. } (18... g6 19. Nf6+ Kh8 20. dxe5 a5 21. Bd5 a4 22. Rd1 Ra6 23. Bxc6 Bxc6 24. Qg3 b4 25. Rh2) 19. gxf6?! { (Mate in 2 → 11.14) Lost forced checkmate sequence. Ne7+ was best. } (19. Ne7+ Kh8 20. Ng6#) 19... Nxf6?! { (11.14 → Mate in 1) Checkmate is now unavoidable. Rf7 was best. } (19... Rf7 20. Ne7+ Kf8 21. Bxf7 Bg4 22. hxg4 Kxf7 23. gxh5 Qxe7 24. Qxg7+ Ke8 25. fxe7 Nxe7 26. dxe5) 20. Qxg7# { White wins by checkmate. } 1-0

We had castled opposite site, and I wanted to start an attack on Black's king. Hence the move h3. Stockfish instead wants me to play d5.
What are the dangers of h3 in this case? What's the idea behind d5? Is there a way to play h3 safely in this position?

Again, following the virtual lines answers the question: now your bishop is your problem. You castled opposite, but the bishop will be pestered by the upcoming pawn storm and/or exchanged by Na5, creating even more "hooks" in your position which Black can use to rip open lines. (Frankly, I didn't expect the position is already that bad.) In contrast, what you exchange after d5 and Bxd7 can't get attacked. Your own pawn storm is a snail in contrast, Black comes first anyway.

12 d5 would force the Nc6 back because it would get trapped after
12 . . . Na5(Nb4)?? 13 Bxd7 and 14 b4(a3).  This gains saveral tempos
compared with allowing Black to play b5 and Na5.  You can still attack with
14 g4 after playing 12 b5 and 13 Bxd7.


text:
Horrible branching rate in kiwipete position
My chess engine can generally get a branching factor 4.5 in the opening and around 7.5 during average middlegame positions. However, I recently tested my engine on the test position Kiwipete and found that the branching rate was nearly 12. Is this the case with other engines?
Here's the position again:
[FEN "r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - 0 1"]

Several notes: I have quiescence search, which normally accounts for about 65-75% of the searched nodes, but I've found in this specific position it takes around 90% of the total nodes (at depth 6: 251,000 normal nodes and 2,286,000 q nodes). I'm wondering if this thing with the q-search is also normal for an engine with a similar branching rate in normal positions.
Additionally, I do have MVV-LVA for move ordering (but not SEE, please tell me how helpful this actually is). I have null-move pruning, which does help quite a bit, but no other kinds of unsafe pruning. I also do not have a TT.


text:
FIDE vs naive vs delete1-Buchholz (Danger, Math)

FIDE-Buchholz BF: the one that is used in "official" tournaments
and defined in the FIDE rules, somewhat complicated. Considers
bye, forfeit and other not played games.
Naive Buchholz BN: Sum of the opponents points.
Delete-1 Buchholz BD: Naive, plus deleting pointwise worst opponent

I just played a tournament, where my competition ended up equal in points, so Buchholz had to decide. Cross table suggested I was in front whoppingly: 4.5 BP. We both played against two different players who played only 5 (me) resp. 2 (him) rounds. Delete for fairness - I'm still 2.5 BP in front. Official table: A tiny 0.5 BP.
Seeing patterns everywhere, since 5-2=3 can't play a role here, let's generalize: A and B played maximally against one C and D having not played all games, C=D is allowed. Assume C and D are deleted by BD. Then for the Buchholz differences of A and B the following holds for my case:
BD=(BN+BF)/2, i.e, the official Buchholz doubles the effect of the delete-1 one.
Is this correct in general?


text:
What engine & setup can I use to analyze a Bughouse position from a single board only (one board), taking into account the pieces in hand?
I have looked at the Sjeng and the Bughousechess.wz.cz website and the answers in the other page. This is not quite a Crazyhouse equivalent analysis, due to the capture mechanics. The pages are very old (Althon, Pentium) and there is no clear statement how to do this.
If necessary, I can take both boards into account, but in particular wanted to see if there was a tactic available.
I have the PGN/screenshot of the position, how can I use Sjeng or similar to analyze it properly?


text:
What are some of the present and past GM known to be autistic?
As an Asperger player, I played from 5 to 10. I won at school and at regional tournaments. I left it
I returned at 18. I spent 15 years playing online and OTB (a lot of daily hours).
My best:

2900 in chess.com tactics trainer.
1950 in rapids (playing 15' games in french Federation).
1750 in slow games at Spanish FEDA.

I have books but I do not read them. I get bored because I do not understand what they say and I have never tried seriously to study theory. I am not good evaluating positions either. I failed many times to match with Stockfish evaluation. Reading here what a master thinks at a position was the definitive read when I knew that was impossible to me. Even I hadn't left chess at 10 I do not think I would have reached more than 2000.
I find I have some kind of limitation in my brain. I only won 1700 because of tactical mistakes and because I know a bit how to enter in won endgames.
I am curious if other autistic players succeeded to "decrypt" chess. Maybe GM Julio Granda is a clear case (related)?

An obvious problem (for research, not for an answer here) is a lack of data. I myself might have some Asperger treats (I'm just a tiny FM and don't count anyway) - but I simply couldn't care less to do an univocal test. Other might think alike.

Maybe GM David Navara ? https://en.wikipedia.org/wiki/David_Navara

@Universal_learner I would edit it, or roll back the change. Somebody has change the meaning of your question after all

@Ian Bush But the answer also includes the term. It is indeed a different question, also interesting to include other people than ASD. But I edited it to speciphy in my case I am Asperger.

@Universal_learner your question, you do with it what you want!

@Ian Bush I decided to change it

I am also neurodiverse and have written a book about that (and a second one is almost done).  I play chess badly but I enjoy it.
I think there are going to be two big issues in answering this question. First, you have to define exactly what you mean by "neurodiverse".  This term is relatively new and the meaning is somewhat in flux.  Second, you have "known to be".  That would indicate you want a list of people who have been diagnosed with something, and are open about it. But a lot of neurodiverse people either a) Don't have an official DX (diagnosis) or b) Aren't open about it.
It's still hard to get a DX (and much harder in some places than others), and there is still a lot of stigma (more in some places than others).
It's tempting, but dangerous, to diagnose from afar and based only on what we read. Was Bobby Fischer neurodiverse?  It sure seems like it, but I doubt he was ever tested.

Might be an idea to define "DX", it's not a term/abbreviation/acronym I have come across

What is your book? Is it available in .epub in Amazon or so?

My book is Screwed Up  Somehow but not Stupid: Life with a Learning Disability.  Support independent book stores by buying it from Bookshop  https://bookshop.org/p/books/screwed-up-somehow-but-not-stupid-life-with-a-learning-disability-peter-flom/11169784?ean=9780692611692

My question was speciphically about ASD. I am sorry but it has no sense to say an schizophrenic decrypted anything, as they have a creative mind (for an ASD it has).