explicitly forbid coercion from MutablePoset into the AsymptoticRing

sagemath · Sep 22, 2015 · 5f54aec · 5f54aec
1 parent 572a95d
commit 5f54aec
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/src/sage/rings/asymptotic/asymptotic_ring.py b/src/sage/rings/asymptotic/asymptotic_ring.py
@@ -1017,6 +1017,9 @@ def _coerce_map_from_(self, R):
             sage: AR_QQ.has_coerce_map_from(ZZ)
             True
         """
+        from sage.data_structures.mutable_poset import MutablePoset
+        if R == MutablePoset:
+            return
         if self.coefficient_ring.has_coerce_map_from(R):
             return True
         elif isinstance(R, AsymptoticRing):