fix: handle multiple heritage in domain

owl2yams/__init__.py

@@ -173,8 +173,9 @@
         for domain_fragment in domain_fragments:
 
             # if the parent of the domain is already in domain_fragments
-            domain_parent = schema[domain_fragment].specializes()
-            if domain_parent is not None and domain_parent.type in domain_fragments:
+            domain_parents_str = schema[domain_fragment]._specialized_type or ""
+            domain_parents = domain_parents_str.split(", ")
+            if set(domain_parents).intersection(set(domain_fragments)):
                 continue
             schema.add_relation_def(
                 RelationDefinition(