Proving the existence of set
58418
Does there exist a set of exactly five positive integers such that the sum of any three distinct elements is prime?
10180
How to prove that this set is closed?
39708
Proving $(A\le B)\vee (B\le A)$ for sets $A$ and $B$
111032
Proof of Sets involving the Cartesian Product
25553
elementary set theory (cartesian product and symmetric difference proof)
151935
Proving the predicate $\forall n \in \mathbb{N} , n \geq 2$ using the Pigeonhole principle
37331
Prove that every set with more than one element has a permutation without fixed points
32441
How to prove or disprove statements about sets
158671
Cardinality of a set that consists of all existing cardinalities
15354
Formal proof of $\exists x \forall y P(x,y) \implies \forall y \exists x P(x,y)$
151984
Proving the existence of a metric space
111954
Computing the cardinality of a combinatorial set
48797
Proving Two Sets are Equal - Infinite Sets - Example
20140
Example of set which contains itself
144787
Show that the set of all infinite subsets of $\mathbb{N}$ has cardinality greater than $\mathbb{N}$
118595
Proving that a set is countable by finding a bijection
44974
Infinite set and countable subsets