Fix nice monomorphism dispatch for HallSubgroup

gap-system · Jan 30, 2016 · 97b1b77 · 97b1b77
1 parent 606200a
commit 97b1b77
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/lib/grpnice.gi b/lib/grpnice.gi
@@ -444,7 +444,11 @@ function(g,l)
 local mon,h;
    mon:=NiceMonomorphism(g);
    h:=HallSubgroup(ImagesSet(mon,g),l);
-   return PreImage(mon,h);
+   if h = fail then
+      return fail;
+   else
+      return PreImage(mon,h);
+   fi;
 end);
 
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