Reply to Manfred, > BCS wrote: > >> CCT!(E, D) // == C >> CCT!(E, C) // == C >> CCT!(E, B) // == A >> CCT!(E, A) // == A >> CCT!(E, F) // == object > To give it a name: > it's the lowest common ancestor (LCA) in the derivation tree. > -manfred > or highest common ancestor (HCL), depending on how you draw your trees. How about, Closest Common Ancestor (CCL)