mathlib3

69686e71 - feat(algebra/category/Module): Tannaka duality for rings (#14352)

feat(algebra/category/Module): Tannaka duality for rings (#14352) Obviously this is not the most interesting statement that one might label "Tannaka duality", but perhaps it can get the ball rolling. :-) Co-authored-by: Scott Morrison <scott.morrison@gmail.com>