## Not all the semigroups \D(2*5) are idempotent generated. ## ## GAP log file gap> n:=5;; G:=PrimitiveGroup(5,2);; a:=Transformation( [ 1, 2, 3, 3, 3 ] );; gap> gens:=List(GeneratorsOfGroup(G), x-> AsTransformation(x, n));; gap> S:=Semigroup(Concatenation(gens, [a]));; gap> Size(S); 365 gap> I:=Idempotents(S, 3); [ Transformation( [ 1, 1, 1, 4, 5 ] ), Transformation( [ 1, 2, 2, 4, 2 ] ), Transformation( [ 1, 2, 3, 1, 1 ] ), Transformation( [ 1, 2, 3, 3, 3 ] ), Transformation( [ 1, 2, 4, 4, 4 ] ), Transformation( [ 1, 5, 5, 4, 5 ] ), Transformation( [ 2, 2, 3, 2, 5 ] ), Transformation( [ 3, 3, 3, 4, 5 ] ), Transformation( [ 4, 4, 3, 4, 5 ] ), Transformation( [ 5, 2, 3, 5, 5 ] ) ] gap> T:=Semigroup(I); gap> Size(T)=Size(S)-Size(G); false gap> LogTo();