diff -r 365e5a0287d6 -r a0a11be5a9cb schema.py
--- a/schema.py	Mon Feb 02 23:17:15 2015 +0100
+++ b/schema.py	Wed Feb 04 21:55:37 2015 +0100
@@ -1094,7 +1094,10 @@
                 if self[objtype].final:
                     raise BadSchemaDefinition('computed relations cannot be final')
                 rdef = ybo.RelationDefinition(
-                    subjtype, rschema.type, objtype)
+                    subjtype, rschema.type, objtype,
+                    __permissions__={'add': (),
+                                     'delete': (),
+                                     'read': ('managers', 'users', 'guests')})
                 rdef.infered = True
                 self.add_relation_def(rdef)