Besides their supporting role with arrows, strings are also known to every linguist and computer scientist to be an integral part of language, as Mark 7:35 attests: "And straightway his ears were opened, and the string of his tongue was loosed, and he spake plain."
(Apparently Vaughn just acquired the King James Version on CD ROM.) The Hebrews and Greeks wrote in strings, as we do, but the Egyptians and Chinese wrote in pictures. Freyd has worked out the beginnings of a diagram-based language, although his statements still appear as strings of diagrams. (Egyptian cartouches, I would argue, are truly not strings.) Atish Bagchi and I will show how logic can be based directly on graphs and diagrams (not strings of them) in our forthcoming paper, "Graph- based logic and sketches." In this case, "forthcoming" probably means in a few months. I will talk about it in Montreal this weekend. (This is a commercial.) Several times lately Vaughn has posted interesting messages on one forum or another and I have answered by criticizing minuscule parts of what he says. Illegitimi non carborundum, Vaughn. One theme in his messages (as I perceive it) is that category theory appears unnecessarily arcane to the rest of the technical world. Let us take heed. -- Charles Wells Department of Mathematics, Case Western Reserve University University Circle, Cleveland, OH 44106-7058, USA 216 368 2893 ==============================================================================