July 24, 2024

Workshop on Categorical Structures for Descent and Galois Theory, Hopf Algebras and Semiabelian Categories

September 23-28, 2002


• George Janelidze
Georgian Academy of Sciences, Tbilisi,Republic of Georgia; University of Aveiro, Aveiro, Portugal
• Bodo Pareigis
University of Munich, Munich, Germany
Walter Tholen
York University, Toronto, Canada

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.

The program of the workshop will commence on Monday September 23, at 9am and run until noon Saturday September 28.

Invited Speakers

Michael Barr McGill University
Francis Borceux
Université Catholique de Louvain
Dominique Bourn Université du Littoral
Ronnie Brown University of Wales
Marta Bunge McGill University
Stefaan Caenepeel Vrije University of Brussels
Aurelio Carboni University of Insubria
Peter Freyd University of Pennsylvania
Johannes Huebschmann Université de Lille
André Joyal UQAM
Max Kelly University of Sydney
F.W. Lawvere University of New York at Buffalo
Andy Magid University of Oklahoma
M. Makkai McGill University
Robert Pare Dalhousie University
Peter Schauenburg University of Munich
Manuela Sobral Universidade de Coimbra
Ross Street Macquarie University
Mitsuhiro Takeuchi University of Tsukuba Sakura-Mura
Myles Tierney Rutgers University
Enrico Vitale Université Catholique de Louvain

Accepted Abstracts

Accepted abstracts may be viewed at


Conference proceedings will appear in the "Communications" series of the Fields Institute, to be published with the American Mathematical Society. In addition, a special volume on Descent Theory will appear in "Applied Categorical Structures" (Kluwer Academic Publishers). Contributed papers to either volume may be sent to any of the three editors, G. Janelidze (, B. Pareigis (, or W. Tholen ( Submissions to the "Communications" must follow the Author Guide (, whereas submissions to the Descent volume should follow the standards of ACS. All contributions will be refereed. The submission deadline for contributions to either volume is 30 November 2002.


Registration is no longer available online. Walk in registratioin is permitted but with limited number of seats for the banquet and excursion, available on a first come first serve basis.

The conference registration fee is $130 CDN for senior researchers/faculty and $65 CDN for students/postdoctoral fellows. This fee includes admission to the workshop banquet and Niagara excursion.

Cancellation Fee: please be aware that there is a $20 charge for cancellations to cover administration costs.


A block of rooms for participants have been arranged at the hotels listed below. Please request the Fields Institute rate when booking . Rooms must be reserved before August 23, 2002 to receive the Fields rate.

Days Inn
30 Carleton Street,
Toronto, ON, M5B 2E9
Tel: 416 977-6655
Toll Free 1-800-367-9601 (8:30 am- 6pm)
(approx. $129/night CDN)
Quality Hotel
280 Bloor Street West
Toronto, ON, M5S 1V8
Tel: (416) 968-0010
Fax: (416) 968-7765
(approx. $115/night CDN)

For additional accommodation resources, please see the Fields Housing page

For further information please contact or