An equality of sets involving two directions
139537
Show that $x\subseteq y \Leftrightarrow \mathcal{P}(x)\subseteq\mathcal{P}(y)$.
148399
Two sets which contain each other as elements
146664
The union of two linearly independent subsets
92249
Every finite set contains its supremum: proof improvement.
1409
Proving that the given set has at most $2^{n-1}$ elements
19289
complement of a set and its measure
115677
Prove the equality of circle's areas
66563
Is $ (A∪B)×(C∩D)=(A∪C)×(B∪D)$ true for all sets A,B,C and D?
136290
a mathematical problem on inequalities
115649
Proving two sets $A, B$ are order isomorphic
111954
Computing the cardinality of a combinatorial set
108807
Subset of a cartesian product
57514
The Minkowski sum of two convex sets is convex
21663
Bijection between power sets of sets implies bijection between sets?
14711
set theoretic function, products of sets (product versus Cartesian product)
35644
Find the supremum of the following set
85819
A non-polyhedral pair $(X,A)$ with both $X$ and $A$ polyhedral