Put in minimal simpset to avoid excessive simplification,
just as in revision 1.9 of HOL/indrule.ML
(* Title: HOL/AxClasses/Tutorial/Monoid.thy
ID: $Id$
Author: Markus Wenzel, TU Muenchen
Define class "monoid".
*)
Monoid = Sigs +
(* monoids *)
axclass
monoid < term
assoc "(x <*> y) <*> z = x <*> (y <*> z)"
left_unit "1 <*> x = x"
right_unit "x <*> 1 = x"
end