Dear Colleagues: We are pleased to announce that a "Workshop on Categorical Structures for Descent and Galois Theory, Hopf Algebras and Semiabelian Categories" will be held September 23-28, 2002, at the Fields Institute in Toronto. For a general description of the theme of the Workshop, see below. A second and more detailed announcement will be sent in January 2002. It will contain a list of invited talks as well as an invitation for a limited number of contributed talks. There is also a webpage about the Workshop at http://www.fields.utoronto.ca/programs/scientific/02-03/galois_and_hopf/ We hope to be able to welcome you at the Workshop. George Janelidze (george_janelidze@hotmail.com) Bodo Pareigis (pareigis@rz.mathematik.uni-muenchen.de) Walter Tholen (tholen@mathstat.yorku.ca)

Theme and Purpose of the Workshop

The goal of the meeting is to spread and to advance categorical methods and their application amongst researchers working in three overlapping areas of algebra, namely in the study of

(I) algebraic structures in monoidal categories and their classical examples, such as Hopf, Frobenius, and Azumaya algebras, and others, particularly those occurring in quantum field theory,

(II) Galois theory vis-a-vis Grothendieck's descent theory, as well as the general theory of separability and decidability, applied particularly to the structures mentioned in (I),

(III) homological algebra of non-abelian structures, such as groups, rings and (associative or Lie) algebras, and its extension to the structures mentioned in (I).

The categorical methods used will include

(i) 2- and higher-dimensional categorical structures, especially symmetric/braided monoidal categories,

(ii) categorical Galois theory, monads and fibrational descent theory, and

(iii) the recently developed theory of protomodular and, more specifically, semiabelian categories, which provides a convenient categorical setting to pursue classical group-theroretic and homological concepts in a very general context.