Dear All,

Next September I am organising a small workshop at Bangor on Orbifolds,
Groupoids and their Applications. I include an announcement giving some
more details.  We hope to provide an oportunity to bridge the gap between
the categorical(mostly topos theoretic and sheaf theoretic) aspects and
the applications (including crystallographic topology, geoemtric group
theory etc.).

Best wishes,

Tim

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           University of Wales, Bangor - School of Informatics,
 
			Mathematics Division


                                Workshop on
                   Orbifolds, Groupoids, and their Applications




                                Announcement

                     Workshop Organiser : Prof Tim Porter

There will be an informal open workshop at the University of Wales Bangor from
11th - 17th September, 2000, on the interplay between orbifolds and groupoids,
together with the application of orbifold methods to problems in
crystallography, geometric group theory and equivariant algebraic
topology. The aim of the Workshop is to provide a venue for the exchange of
information on different aspects of the area and to encourage collaboration
across the different subject specialisms that are involved. Some time will be
set aside for examination of the problems where existing techniques seem not to be adequate. 

The workshop is in part to celebrate the work on groupoids, their theory and
applications, by Ronnie Brown who has recently retired from a full time professorship a
t Bangor. It will also form part of his (belated) 65 birthday celebrations! 

The workshop will be informal. Although there will be some survey talks, it is
hoped that the main work will be concentrated on the future in `discussion
mode' rather than lecture, (so participants are encouraged to interrupt!!!) We
hope that questions such as to the interpretation of homotopy theoretic
information on orbifold, the applicability of current algebraic - topological
techniques to problems in `crystallographic topology' and the link between
orbifolds and sheaf theory will be addressed. The background of the
participants is from various subject areas (crystallography, geometric group theory, 
category theory etc.) and one task is to find a common language where
everyone has a moderate chance of understanding and communicating their
questions. There may be some need for quick sketches of background
assumptions, theory etc and because of this sessions are likely to be of
variable length and the timetable will be (by necessity) flexible. 

At present the list of participants includes: 

      R.Brown (Groupoids and their applications) 
      A. Haefliger (Geometric group theory, groupoids and geometry) 
      C. Johnson (Crystallographic Topology) 
      I. Moerdijk (Category Theory, orbifolds and toposes) 
      D. Pronk (Sheaves on orbifolds) 

Various U.K. researchers in differentiable groupoids, equivariant homotopy and its a
pplications and related areas are also expected. 

Additional participants are very welcome. 

Accommodation is likely to be in the student village (en-suite facilities) at a short 
distance (5 to 10 minutes walk) from the Mathematics building. (Further
information about accommodation in and abound Bangor is available.) 

A small registration fee of £20 is requested to cover the cost of a workshop dinner a
nd daily coffee/tea etc. We will be seeking some financial support from
various organisations so may be able to give limited help to some participants
(priority would be given to postgraduates). 

There will be some space for a display of preprints/ offprints and `posters'. 

If you are interested in attending the workshop, contact me by e-mail: t.porter@bangor.ac.uk 
in the first instance. For further information check the workshop home page. 




 
************************************************************
Timothy Porter                    |tel direct:        +44 1248 382492
Mathematics Division,		  |World Wide Web
School of Informatics,            |home page:
http://www.bangor.ac.uk/~mas013/
University of Wales, Bangor       |Mathematics and Knots : exhibition
Dean St.                          |http://www.bangor.ac.uk/ma/CPM/
Bangor                            |
Gwynedd LL57 1UT                  |
United Kingdom                    |