merge accepting and rejecting functors in all cases

sagemath · Jan 23, 2016 · c4a0e22 · c4a0e22
1 parent aeae8f3
commit c4a0e22
Showing 1 changed file with 2 additions and 4 deletions.
diff --git a/src/sage/symbolic/subring.py b/src/sage/symbolic/subring.py
@@ -758,8 +758,7 @@ def merge(self, other):
         elif type(self) == type(other):
             return type(self)(self.vars & other.vars)
         elif isinstance(other, SymbolicSubringRejectingVarsFunctor):
-            if not (self.vars & other.vars):
-                return self
+            return type(self)(self.vars - other.vars)
 
 
     def _apply_functor(self, R):
@@ -965,8 +964,7 @@ def merge(self, other):
         elif type(self) == type(other):
             return type(self)(self.vars | other.vars)
         elif isinstance(other, SymbolicSubringAcceptingVarsFunctor):
-            if not (self.vars & other.vars):
-                return other
+            return type(other)(other.vars - self.vars)
 
 
     def _apply_functor(self, R):