Is there such a thing as the set of "definable" numbers?
17022
Definable real numbers
124847
Is the set of surjective functions from $\mathbb{N}$ to $\mathbb{N}$ uncountable?
70262
Can the axiom of choice be used to define the real numbers?
144181
Given an arbitrary set $X$, can one always find an element outside $X$?
73612
Is there a Non-prime Number that is Divisible only by Numbers Greater than its Square Root?
106272
Do numbers exist independently from observers?
82260
List out all the definable set in given model
109054
Given an infinite set of cardinality $X$, is there a chain in $\mathcal P(X)$ of the same cardinalty of $\mathcal P(X)$?
89749
Example of a not recursively enumerable set $A \subseteq \mathbb{N}$
86263
How do we show there are the same number of elements in each of the sets?
118175
Can we say that $\frac{0}{0}$ is every number?
93721
Are numbers in which all substrings are primes finite regardless of base?
80019
$\varepsilon$-number countability without choice
65768
What is the cardinality of the set of the empty set?
7733
If A is infinite, does there have to exist a subset of A that is equivalent to A?
108748
Why there are real numbers with infinite digits, but no such natural numbers (or another reason why real numbers are uncountable)
34387
Is the number of irreducibles in any number field infinite?