Hi Tzahi Since you seem to know about full disjunctions, I was wondering if you could answer this question: Can full disjunction be implemented as a binary operator? The algorithms I've seen for computing it seem to require that all input relations be supplied at once. Even in your message above you specified your example as FD(A,B,C) rather than say (A fd B) fd C. So I was wondering if the latter is possible? The reason I ask is that I'm currently trying to solve a problem that could in principle be solved using FD but it would fit into my current framework much better if it were a binary operator like the other joins. Thanks in advance. Lee
