semitrans.gi: fix WreathProduct second method

gap/semigroups/semitrans.gi

@@ -788,7 +788,8 @@ InstallMethod(WreathProduct,
 "for a transformation semigroup and a permutation group",
 [IsPermGroup, IsTransformationSemigroup],
 function(G, S)
- local maps, newmap, gensG, gensS, next, reps, orbs, gen1, n, i, s, x, m;
+ local maps, newmap, gensG, gensS, next, reps, orbs, gen1, n, i, s, x, m, y,
+ rimage;
  if not IsMonoidAsSemigroup(S) then
  ErrorNoReturn("Semigroups: WreathProduct: usage,\n",
  "the first argument <S> should be a monoid,");
@@ -800,9 +801,15 @@ function(G, S)
  gensG := List(gensG, x -> OnTuples([1 .. m], x));
  gensS := GeneratorsOfSemigroup(S);
 
- orbs := ComponentRepsOfTransformationSemigroup(S);
-
+ orbs := List(ComponentsOfTransformationSemigroup(S), x -> Minimum(x));
  n := DegreeOfTransformationCollection(S);
+ rimage := [1 .. n];
+
+ for x in orbs do
+ for y in gensS do
+ RemoveSet(rimage, x ^ y);
+ od;
+ od;
 
  maps := []; # final generating set for the wreath product
 
@@ -823,6 +830,15 @@ function(G, S)
  Add(maps, Transformation(newmap));
  od;
  od;
+
+ for i in rimage do
+ newmap := OnTuples([1 .. m * n], maps[1]);
+ for x in gensG do
+ newmap{[1 .. m] + (i - 1) * m} := x + (i ^ gen1 - 1) * m;
+ Add(maps, Transformation(newmap));
+ od;
+ od;
+
  return Semigroup(maps);
 end);