 
Summary: Boris Svistunov
University of Massachusetts, Amherst
Diagrammatic Monte Carlo
Nikolay Prokof'ev
Kris Van Houcke (Umass/Ghent)
Evgeny Kozik (ETH Zurich)
Lode Pollet
Felix Werner
Sign Problems and Complex Actions, ECT*, Trento, March 26, 2009
Sign PROBLEM and Sign PROBLEM
Extensive configurational space Diagrams (intensive configurational space)
is the configuration volume
is the correlation volume
can be significantly reduced by
partial summation
is the diagram order
The issue of summability: Can an asymptotic series be regularized?
1. Fermions can be put on a lattice...
2. Bosons can be represented as pairs of fermions...
Dyson's argument: The perturbative series has zero convergence radius if
