Hi list, I've been working a system of natural deduction that is a sort of a natural deduction version for the systems in the \lambda-cube, and I just realized that probably other people could have also attempted to do that before me, and that I should take a look at their papers... Anyone knows of any work in that direction? Thanks in advance, cheers, Eduardo Ochs http://angg.twu.net/ ochs@math.mcgill.ca