mathlib

0e943b15 - feat(order/boolean_algebra, set/basic): some compl lemmas (#14508)

feat(order/boolean_algebra, set/basic): some compl lemmas (#14508) Added a few lemmas about complementation, and rephrased `compl_compl` and `mem_compl_image` to apply in `boolean_algebra` rather than `set (set _ ))`. Co-authored-by: Floris van Doorn <fpvdoorn@gmail.com>