set IsInjective flag before calling SetNiceMonomorphism (#870)

* set `IsInjective` flag before calling `SetNiceMonomorphism` * Update gap/attributes/isomorph.gi Co-authored-by: James Mitchell <james-d-mitchell@users.noreply.github.com>
semigroups · Sep 17, 2022 · 57420f3 · 57420f3
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commit 57420f3
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diff --git a/gap/attributes/isomorph.gi b/gap/attributes/isomorph.gi
@@ -315,7 +315,9 @@ function(S)
                                                   map(p),
                                                   map(p ^ -1)));
   H := Group(Y);
-  SetNiceMonomorphism(H, GroupHomomorphismByImagesNC(H, G, Y, X));
+  map := GroupHomomorphismByImagesNC(H, G, Y, X);
+  SetIsBijective(map, true);
+  SetNiceMonomorphism(H, map);
   SetIsHandledByNiceMonomorphism(H, true);
   UseIsomorphismRelation(H, G);
   return H;

diff --git a/gap/attributes/isorms.gi b/gap/attributes/isorms.gi
@@ -616,6 +616,7 @@ function(G)
                                                        G,
                                                        GeneratorsOfGroup(H),
                                                        GeneratorsOfGroup(G)));
+  SetIsBijective(iso, true);
   SetNiceMonomorphism(G, iso);
   SetIsHandledByNiceMonomorphism(G, true);
   UseIsomorphismRelation(G, H);