mathlib

30daa3c0 - chore(logic/is_empty): add lemmas for subtype, sigma, and psigma (#15134)

chore(logic/is_empty): add lemmas for subtype, sigma, and psigma (#15134) This reorders the nonempty lemmas to put `sigma` next to `psigma`. The resulting `is_empty` and `nonempty` lemmas are now in the same order.