gprd.gi: preserve properties in DirectProduct more intelligently

gap-system · Nov 25, 2018 · d3c6e9f · d3c6e9f
1 parent 3ddd860
commit d3c6e9f
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Showing 2 changed files with 8 additions and 2 deletions.
diff --git a/lib/gprd.gi b/lib/gprd.gi
@@ -31,8 +31,10 @@ local d, prop;
   for prop in [IsFinite, IsNilpotentGroup, IsAbelian, IsSolvableGroup, IsBand,
                IsInverseSemigroup, IsRegularSemigroup, IsIdempotentGenerated,
                IsLeftZeroSemigroup, IsRightZeroSemigroup, IsZeroSemigroup] do
-    if ForAll(arg, Tester(prop)) then
-      Setter(prop)(d, ForAll(arg, prop));
+    if ForAny(arg, x -> Tester(prop)(x) and not prop(x)) then
+      Setter(prop)(d, false);
+    elif ForAll(arg, x -> Tester(prop)(x) and prop(x)) then
+      Setter(prop)(d, true);
     fi;
   od;
 

diff --git a/tst/testinstall/gprd.tst b/tst/testinstall/gprd.tst
@@ -47,6 +47,10 @@ true
 gap> d3 := DirectProduct(g2, g2);;
 gap> HasIsFinite(d3) and not IsFinite(d3);
 true
+gap> g3 := SymmetricGroup(5);;
+gap> d4 := DirectProduct(g1, g2, g3);;
+gap> HasIsFinite(d4) and not IsFinite(d4);
+true
 
 #
 gap> STOP_TEST("gprd.tst");