## Not all the semigroups \C(5) are idempotent generated. ## ## GAP log file gap> n:=5;; G:=PrimitiveGroup(5,1);; a:=Transformation( [ 1, 3, 2, 2, 2 ] );; gap> gens:=List(GeneratorsOfGroup(G), x-> AsTransformation(x, n));; gap> S:=Semigroup(Concatenation(gens, [a]));; gap> Size(S); 360 gap> I:=Idempotents(S, 3);; gap> T:=Semigroup(I); gap> Size(T)=Size(S)-Size(G); false