proving infinite set from a finite and infinite set
134071
If A is a finite set and B is an infinite set, then B\A is an infinite set
66398
Union of a finite set and a countably infinite set is countably infinite
81682
Proving the algebraic set corresponding to a polynomial is infinite.
136755
Direct proof of empty set being subset of every set
83518
Proving Two sets have same cardinality
67295
Please check my proof for $N$ is infinite
45792
Rigorous proof that surjectivity implies injectivity for finite sets
16826
prove that every infinite subset of compact set H has a limit point (Explanation)
94825
Open set as a finite union of closed sets
139078
Infinite partition of $\mathbb N$ by infinite subsets
158882
Prove the existence of some weird family of sets
21820
How to prove that a set is invariant?
65316
Explaining Infinite Sets and The Fault in Our Stars
148992
A finite set is closed
34099
Proving that the empty set is unique
128437
How to prove that a finite set is countable
127656
How to prove that if $A$ is infinite and $B$ is finite, then $|A\cup B|=|A|$?