--- a/ontology/components/assumedBy.ttl	Mon Sep 19 16:01:27 2011 -0400
+++ b/ontology/components/assumedBy.ttl	Mon Sep 19 16:04:44 2011 -0400
@@ -7,3 +7,12 @@
    rdfs:domain prov:Role;
    rdfs:range [ owl:complementOf prov:Entity ];
 .
+
+prov:Role 
+   rdfs:subClassOf prov:Entity;
+   rdfs:subClassOf [
+      a owl:Restriction;
+      owl:onProperty prov:assumedBy;
+      owl:minCardinality 1;
+   ]
+.