mathlib

b14f22e9 - chore(algebra/algebra and group_theory/group_action): move a lemma (#10425)

chore(algebra/algebra and group_theory/group_action): move a lemma (#10425) Move a lemma about the action of a group on the units of a monoid to a more appropriate place. It accidentally ended up in `algebra/algebra/spectrum` but a better place is `group_theory/group_action/units`. Co-authored-by: Eric Wieser <wieser.eric@gmail.com>