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 Events
PhD Defense - Aurel Meyer
Tue 6 Jul 2010, 12:30pm SPECIAL
One Time Event
Graduate Student Centre, Room 203
Essential Dimension of Algebraic Groups
Graduate Student Centre, Room 203
Tue 6 Jul 2010, 12:30pm-2:00pm

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UBC
Wed 7 Jul 2010, 4:00pm
Topology and related seminars
WMAX 110
Finiteness Obstructions for G-Spaces up to hG-equivalence
WMAX 110
Wed 7 Jul 2010, 4:00pm-5:00pm

Abstract

Abstract: Two G-spaces X and Y are said to be hG-equivalent if their Borel constructions are equivalent over BG.  In this talk we introduce an obstruction which determines when a G-sphere X is hG-equivalent to a finite G-sphere Y, at a prime p dividing the order of G.  We will also discuss how to generalize this to a global finiteness obstruction, and, in the case  of G-spheres, relate the finiteness obstruction to the dimension function of a G-sphere.
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PhD defense - James Clarkson
Fri 9 Jul 2010, 9:00am SPECIAL
One Time Event
Graduate Student Centre, Room 203
Group Actions on Finite Homotopy Spheres
Graduate Student Centre, Room 203
Fri 9 Jul 2010, 9:00am-10:00am
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Vladimir Dorodnitsyn
Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Moscow
Tue 20 Jul 2010, 3:30pm SPECIAL
One Time Event
Math Annex 1102
Difference equations: symmetries, exact solutions, conservation laws
Math Annex 1102
Tue 20 Jul 2010, 3:30pm-4:30pm

Details

A review of several applications of Lie groups of  transformations to  difference  equations,  meshes  (lattices)  and difference functionals is presented. Examples of difference models (i.e. difference equations and  appropriate  meshes) which admit the same symmetry group as there continuous counterparts are presented.

For integrable cases of ODEs, discrete representations of ODEs  ("an  exact finite-difference scheme") are developed. Invariant variational problems for difference equations are considered.  Lagrangian and Hamiltonian formalisms and  Noether-type constructions for  difference functionals, meshes and difference equations are illustrated by several examples.
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University of Western Ontario
Wed 21 Jul 2010, 3:00pm
Topology and related seminars
WMAX 216
Galois descent and pro objects
WMAX 216
Wed 21 Jul 2010, 3:00pm-4:00pm

Abstract

 A Galois descent theorem for n-types will be displayed and explained. This result is used, together with an appropriate version of the homotopy theory of pro objects, to give a descent criterion for diagrams of spaces which are defined on the etale site of a field. The need for such a criterion first arose in connection with the algebraic K-theory of fields.
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