
CMS CoxeterJames Lecture / Conférence CoxeterJames de la SMC
 KAI BEHREND, University of British Columbia
Quantum Cohomology and the virtual fundamental class
or ``how to count properly''

Motivated by the desire to have beautiful formulas, mathematicians have
realized time and again that it is necessary to change the meaning of
the ``number of solutions'' to a problem. The simplest case is maybe
the introduction of the complex numbers in order for the theorem ``any
quadratic equation has two solutions'' to become true. The introduction
of GromovWitten invariants (i.e., quantum cohomology) into
algebraic geometry can be understood as another step in this program.
This talk is meant to be a somewhat leisurly introduction to some of
the ideas involved in this long story.

