Symmetric difference of 3 sets
12459
Associativity of symmetric difference of sets
44943
The 3 different equals
36980
Prove the third isomorphism theorem
79531
Distance between sets with one closed set and one compact set
38807
Does set difference distribute over set intersection?
18788
Derangements of multisets
9850
How many ways are there to choose 3 subsets $A,B,C$ of a set $\{1,2,3...n\}$ such that $ A \cap B \cap C = \emptyset $
113083
How to prove a set equality?
21820
How to prove that a set is invariant?
40848
$a\mid b,c\mid d\Rightarrow\,\gcd(a,c)\mid \gcd(b,d)$
97254
What is the proof of permutations of similar objects?
35648
How many permutations of the set n={1,2,3,3,3,4,4,5} are possible without any consecutive identical elements?
111032
Proof of Sets involving the Cartesian Product
85023
Permutation of n objects with restriction of adjacent pairs
60110
The set of differences for a set of positive Lebesgue measure
112084
Proof of a formula for the power set of a union of two sets
82410
Find $C$, if $A=CBC$, where $A$,$B$,$C$ are symmetric matrices.