52 commits

Author	SHA1	Message	Date
Jeremy Avigad	4420f0dc0c	feat(library/algebra/group): add ordered semigroups	2014-11-17 18:32:14 -08:00
Jeremy Avigad	0d982cceed	feat(library/algebra/ring): begin theory of semirings and rings	2014-11-14 17:27:35 -08:00