description of Grothendieck "topologies". Anders Kock later found further simplifications so that a topos can be described as a category with products and equalizers in which the notions of map space and subobject are representable. Lawvere had pointed out that a Grothendieck topology can be entirely described as an endomorphism of the subobject representor, and Tierney showed that the conditions it needs to satisfy are just idempotence and the preservation of finite intersections. These "topologies" are important in both algebraic geometry and model theory because they determine the subtoposes as sheaf-categories. Dalhousie University in 1969 set up a group of 15 Killam-supported researchers with Lawvere at the head; but in 1971 it terminated the group. Lawvere was controversial for his political opinions, for example, his opposition to the 1970 use of the War Measures Act, and for teaching the history of mathematics without permission. But in 1995 Dalhousie hosted the celebration of 50 years of category theory with Lawvere and Saunders Mac Lane present. Lawvere ran a seminar in Perugia, Italy (1972–1974) and especially worked on various kinds of enriched category. For example, a metric space can be regarded as an enriched category. From 1974 until his retirement in 2000 he was professor of mathematics at University at Buffalo, often collaborating with Stephen Schanuel. In 1977 he was elected to the Martin professorship in mathematics for five years, which made possible the meeting on "Categories in Continuum Physics" in 1982. Clifford Truesdell participated in that meeting, as did several other researchers in the rational foundations of continuum physics and in the synthetic differential geometry that had evolved from the spatial part of Lawvere's categorical dynamics program. Lawvere continued to work on his 50-year quest for a rigorous flexible base for physical ideas, free of unnecessary analytic complications. He was professor emeritus of mathematics and adjunct professor emeritus of philosophy at Buffalo. Awards and honors In 2010 he received the "Premio Giulio Preti", awarded by the Regional Council of Tuscany In 2012 he became a fellow of the American Mathematical Society. Selected books 1986 Categories in Continuum Physics (Buffalo, N.Y. 1982), edited by Lawvere and Stephen H. Schanuel (with Introduction by Lawvere pp 1–16), Springer Lecture Notes in Mathematics 1174. ; ebook 2003 (2002) Sets for Mathematics (with Robert Rosebrugh). Cambridge Uni. Press. 2009 Conceptual Mathematics: A First Introduction to Categories (with Stephen H. Schanuel). Cambridge University Press, 2nd ed. ;