Early line in english opening not in the chessbase powerbook 2019 but seen by stockfish 10 64bits under latest fritz I am looking at 1.c4 Nf6 2.g3 d5 3.Bg2 dxc4 4.Nf3 and Chessbase's Powerbook 2019 only proposes 4...c6, 4...g6, 4...a6, 4...Nbd7, 4...Qd6 or 4...Be6 whereas Fritz 17 64bits latest update using Stockfish 10 64bits finds this line :



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1.c4 Nf6 2.g3 d5 3.Bg2 dxc4 4.Nf3 Nc6 5.Qa4 Nd7 6.Qxc4 e5 7.O-O Be7 8.b3 Nb6 9.Qc2 O-O 10.Bb2 Nb4 11.Qc3 f6 12.a3 Nc6 13.d3 Be6 14.Nbd2 Qd7 15.Rac1 Rfd8 16.Qc2 a5 17.Rfd1 Bd5 18.Re1 Bf7 19.Ne4 h6 20.Nfd2 Be6 21.Red1 Bd5 22.Nc5 Bxc5 23.Qxc5 Bxg2 24.Kxg2 Kh8


Either the quality of the Powerbook 2019 is not that high, either Stockfish 10 64bits is cracking, which I doubt. Am I right or do I miss a parameter ?
I also have PowerBook 2019, and Stockfish 10, and I can confirm what you found, but there is an explanation.

The moves suggested in the PowerBook are from actual human games. They are intended, specifically, to give the computer a human opening book, rather than it just playing on its own. You will find these games in the database Powergames2019 that came with the product.

This goes back to the old days, when computers were not as strong as they are today. It was then beneficial to have a human opening book. Today, one could make the argument that it is not so necessary.

P.S. For the record, Masters have a natural proclivity not to block the c-pawn, either as white or black in closed openings since you need to play c5 so often to try and free your game. That is the reason the Chigorin is not so popular.