Comments concerning diagram drawing packages for TeX: 1. As some have already said, TeX needs a general drawing module in the spirit of commercial drawing programs. A package for implementing diagrams as used by categorists could be added on top of that. Mathematicians communicate with structured drawings of all sorts, not just category diagrams. *************************************************************** * A system for producing printed mathematical texts that does * * not provide for sophisticated drawing as well as * * sophisticated setting of text is _only_half_a_system_ * * because mathematics is the marriage of geometry and logic. * *************************************************************** Such a drawing module, of course, is not really part of the LaTeX-s project. 2. xypic and Paul Taylor's package use a grid metaphor with syntax based on TeX's array notation. Mike Barr has suggested another grid based notation in which you refer to the grid points by coordinates. I have not used either system but Mike's looked easier to use. I am a mathematician. I THINK the respondents who liked the array notation systems were computer scientists. I suspect there may be a connection. Most mathematicians are in math departments and have to teach calculus regularly, so are used to locating points by coordinates. Perhaps computer scientists are less used to such things and more used to learning new syntax. What is amenable syntax is a very personal thing. I think I could learn to use xypic's & notation easily; I KNOW I could use the name-the-coordinates system because it is just like what I do when I teach calculus. Mike Barr's original syntax is still good for common simple squares and triangles, and his underlying \putmorphism macro works pretty well for very complicated diagrams that are not obviously grid-based. It has two flaws: you have to put in \phantoms on overlapping nodes, which is a royal pain, and you are restricted as to the angles you can draw arrows. Both flaws are the result of flaws in the underlying system. I repeat: We need a full-fledged drawing module. I would expect a grid-based system to work better than Mike's for complicated diagrams in which imposing a grid structure does not do too much violence to the original diagram, since Mike's shapes are a pain to paste together. I've become rather proficient at using Mike's system, but it's like programming in assembly language whereas the grid based systems look like programming in a higher level language. Charles Wells Department of Mathematics Case Western Reserve University 10900 Euclid Avenue Cleveland, OH 44106-7058 216-368-2893 cfw2@po.cwru.edu +++++++++++++++++++++++++++++++++++++