This Set Identity is Beautiful!

追加: 2026-05-25

[00:00:00]Here is a beautiful identity from set theory.

[00:00:03]A minus B means take everything in A and remove the part that belongs to B.

[00:00:10]Now look at A intersection B complement.

[00:00:13]B complement means everything outside B.

[00:00:17]When we intersect that with A, we again get the part of A outside B.

[00:00:23]Different notation, same shaded region.

[00:00:27]That's why A minus B is equal to A intersection B complement. Mathematics is easier when you visualize it.