monoid.clif revision 38eb8e414b6c73efa6bcf81760625385094b757b
(cl-text http://colore.oor.net/magma/monoid.clif
(cl-imports http://colore.oor.net/magma/semigroup.clif)
(exists (e)
(forall (x)
(and (= x (op e x))
(= x (op x e)))))
)