mathlib3

4b9d94dc - feat(data/[fin]set): add some more basic properties of (finite) sets (#948)

feat(data/[fin]set): add some more basic properties of (finite) sets (#948) * feat(data/[fin]set): add some more basic properties of (finite) sets * update after reviews * fix error, move pairwise_disjoint to lattice as well * fix error