proved by · authored relationshipmoderator test · authored relationshipcommand lemma · authored relationshipillustrated by · authored relationshipstated over · authored relationshipassumes · authored relationshipcaller identity from · authored relationshipdescribes · authored relationshipuses helper specs · authored relationshipimplemented by · authored relationshipchecked against · authored relationshipbuilt from accepted steps of · authored relationshipOnly the author or a moderator deletes a postGUARANTEEOnly the author or amoderator deletes a postPolicy holds on reachable statesTHEOREMPolicy holds on reachablestatesWhat delete writesTHEOREMWhat delete writesBob cannot delete Alice's postTHEOREMBob cannot delete Alice'spostPermission policySPECIFICATIONPermission policyModerator membershipSPECIFICATIONModerator membershipReachable stateASSUMPTIONReachable stateAuthenticated callerBOUNDARYAuthenticated callertransitionIMPLEMENTATIONtransitiondeleteIMPLEMENTATIONdeletetext_ok, find_post, is_moderatorIMPLEMENTATIONtext_ok, find_post,is_moderator