Since 2002 Perimeter Institute has been recording seminars, conference talks, and public outreach events using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities. Recordings of events in these areas are all available On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA).
PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
will describe a new method for understanding a large class of
generalized complex manifolds, in which we view them as usual
symplectic structures on a manifold with a kind of log structure. I
will explain this structure in detail and explain how it can be used
to prove a Tian-Todorov unobstructedness theorem as well as
topological obstructions for existence of nondegenerate generalized
Ordinary differential equations become much less ordinary
when they are allowed to have singularities.
Solving them naively in formal power series, one often obtains divergent
series, just as in the perturbation series for physical observables in quantum
The concept of wall-crossing structure (WCS for short) was introduced
recently in my joint work with Maxim Kontsevich. WCS appear in different
disguises in the theory of Donaldson-Thomas invariants of Calabi-Yau
3-folds, quiver representations,integrable systems of Hitchin type,
cluster algebras, Mirror Symmetry, etc.
I plan to discuss the
definition of WCS and illustrate it in several well-known examples. If
time permits I will speak about a special class of WCS called rational
quantum gravity, as generating series of discrete surfaces, and
sometimes toy models for string theory. The single trace matrix models
(with measure dM exp( - N Tr V(M)) have been solved in a 1/N expansion
in the 90s by the moment method of Ambjorn et al. Later, Eynard showed
that it can be rewritten more intrinsically in terms of algebraic
geometry of the spectral curve, and formulated the so-called topological