@@ -149,8 +149,8 @@ group groupAttrNames newAttrName rel@(Relation oldAttrs tupleSet) = do
149149--algorithm: self-join with image relation
150150group :: S.Set AttributeName -> AttributeName -> Relation -> Either RelationalError Relation
151151group groupAttrNames newAttrName rel = do
152− let nonGroupAttrNames = A.attributeNamesNotContained groupAttrNames (S.fromList (V.toList (A.attributeNames (attributes rel))))
153− nonGroupProjectionAttributes <- A.projectionAttributesForNames nonGroupAttrNames (attributes rel)
152+ let nonGroupAttrNames = A.nonMatchingAttributeNameSet groupAttrNames (S.fromList (V.toList (A.attributeNames (attributes rel))))
153+ nonGroupProjectionAttributes <- A.projectionAttributesForNames nonGroupAttrNames (attributes rel)
154154 groupProjectionAttributes <- A.projectionAttributesForNames groupAttrNames (attributes rel)
155155 let groupAttr = Attribute newAttrName (RelationAtomType groupProjectionAttributes)
156156 matchingRelTuple tupIn = case imageRelationFor tupIn rel of