Dear All, I've just posted a note on the arXiv, giving a short proof by counterexample that the category of 3-computads is not cartesian closed. http://arxiv.org/abs/1209.0414 This result was first proved by Makkai and Zawadowski: 3-computads do not form a presheaf category. Journal of Pure and Applied Algebra, 212(11):2543--3546, 2008. Their original proof depended on some results on Artin glueing of Carboni and Johnstone, and in turn some results of Day. Recently François Métayer asked me if I knew of a direct counterexample instead, that is, a 3-computad B such that the functor _ x B does not have a right adjoint. I did not know of anywhere that such a counterexample had been written up. So I constructed one, and after showing it to François and others at Paris 7, decided it might be useful to make the notes available. The counterexample uses the same ideas as the proof of Makkai and Zawadowski (essentially coming down to an Eckmann-Hilton argument) but the proof is self-contained in this 8 page note, and the counterexample itself is given in two pages in the middle. I hope that this will help people further understand the very interesting and crucial result of Makkai and Zawadowski. Comments are welcome. Regards, Eugenia [For admin and other information see: http://www.mta.ca/~cat-dist/ ]