functional equality of unions/intersections
52323
Maps - question about $f(A \cup B)=f(A) \cup f(B)$ and $ f(A \cap B)=f(A) \cap f(B)$
96243
limsup of intersection of events as a subset of intersection of limsups
84609
Unary intersection of the empty set
57938
When do two functions become equal?
88603
verify equicontinuous functions
146664
The union of two linearly independent subsets
36789
The power set of the intersection of two sets equals the intersection of the power sets of each set
89506
Union of disjoint sets : Equivalence relations
152193
The intersection of a closure with an open set
105594
Fixed point, union of $\aleph_0, \aleph_{\aleph_0},\aleph_{\aleph_{\aleph_0}}\dots$ [see Noah's comment on notation]
141101
Russia (2000) contest:Prove the existence of a pair of rows and columns with intersections differently coloured
26530
What does the big intersection or union sign of a set mean?
76192
Intersection of volumes defined by inequalities
150311
Intersection of two `std::map`s
87830
Relating the union of the power set of a set to the set itself
54156
Elegant ways to support equivalence ("equality") in Python classes
24045
Efficiently compute Intersection of two Sets in Java?