ManifoldSubsetPullback.is_closed: Preimage of finite sets is closed

sagemath · Jun 24, 2021 · 07aba9e · 07aba9e
1 parent d321b93
commit 07aba9e
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/src/sage/manifolds/subsets/pullback.py b/src/sage/manifolds/subsets/pullback.py
@@ -771,7 +771,7 @@ def is_closed(self):
             sage: McF = ManifoldSubsetPullback(c_cart, F, name='McF'); McF
             Subset McF of the 2-dimensional topological manifold R^2
             sage: McF.is_closed()
-            False
+            True
 
         """
         if self.manifold().dimension() == 0:
@@ -798,6 +798,8 @@ def is_closed(self):
                 if self._codomain_subset.rank() == self._codomain_subset.base_extend(RR).dimension():
                     # Discrete subgroup of R^n
                     return True
+        elif self._codomain_subset in Sets().Finite():
+            return True
         else:
             if hasattr(self._codomain_subset, 'is_topologically_closed'):
                 try: