mathlib

3b09a260 - feat(ring_theory/artinian): localization maps of artinian rings are surjective (#15736)

feat(ring_theory/artinian): localization maps of artinian rings are surjective (#15736) The proof is by Junyan, I just tidied it up a little, and also the `ring_theory/artinian` file a little bit, in order to fit the results more smoothly. Co-authored-by: Junyan Xu <junyanxumath@gmail.com> Co-authored-by: Eric Rodriguez <37984851+ericrbg@users.noreply.github.com>