Using Pigeonhole principle to prove a subset statement
37783
Proving that a set of 2016 natural numbers contain a non-empty set with a sum divisible by 2016
143573
Problem (1.8) A Path to Combinatorics Solution Verification.
116527
Validating a proof for necessary and sufficient conditions on sets A & B such that $P(A) \cup P(B) = P(A\cup B)$
123690
Olympiad question on Pigeonhole principle
100977
Infinite subset with pairwise comprime elements
111032
Proof of Sets involving the Cartesian Product
23764
Proving that $A+A \not\subset 2A $ using a particular definition for sum of sets
77791
Proving an inclusion related to algebraic sets and interpreting it
132605
Finding the number of subsets of a set such that an element divides the succeeding element.
3392
Sum of products of elements of nonempty subsets of A set
30136
Proof that a Combination is an integer
134120
Prove statement with a counter-example: For all sets S, T and V, V ∪ (S ∩ T) = (V ∪ S) ∩ T is false
117658
A set with n elements has 2^n subsets
123613
Double Complement of a set proof
153072
Guessing a subset of $\{1,...,N\}$
32441
How to prove or disprove statements about sets
142993
Proof of A ⊆ C and B ⊆ C ⇔ A ∪ B ⊆ C