Why are we allowed to reference parameters outside the language of set theory?
57856
Axiom Schema of Separation Parameters
120712
Is there a way to define the "size" of an infinite set that takes into account "intuitive" differences between sets?
58602
In ZF, how would the structure of the cardinal numbers change by adopting this definition of cardinality?
156089
Why is the associative property valid for modular arithmetic?
3663
Finding counterexamples in elementary set theory.
146188
Why does a proof of $\exists f: X\to Y$ injection $\iff \exists g: Y \to X$ surjection requires the axiom of choice?
70166
Why is the universal quantifier $\forall x \in A : P(x)$ defined as $\forall x (x \in A \implies P(x))$ using an implication?
113640
Why is there this strange contradiction between the language of logic and that of set theory?
58447
Is axiom of choice required for there to be an infinite linearly independent set in a (non-finite-dimensional) vector space?
65308
Axiom of Choice: Family of non-empty sets mutually disjoint or not?
147908
Why use the biconditional in the Axiom of Extensionality
20004
Meta Theory when studying Set Theory
140583
What does it mean for something to hold "up to isomorphism"?
54497
Set Notation - Inclusion and Proper Inclusion
66636
Problems with introducing ordered pairs axiomatically
20140
Example of set which contains itself
1027
Why is this true? $(\exists x)(P(x) \Rightarrow (\forall y) P(y))$