Archive for sign problem

Alésia sunset

Posted in pictures, Running, Statistics, University life, Wines with tags , , , , , , , on July 12, 2013 by xi'an

IMG_0305Mark Girolami came on Monday for a short visit at CREST this week, to discuss further the Russian roulette with Nicolas and I (and evacuate some of my “worries”), exploit the potential links with vanilla Rao-Blackwellisation, and look at other directions of common interest. In the conversation, we spent a while pondering about the “sign problem”, namely the difficulty with signed unbiased estimates of positive normalising constants. Quickly bumping into the impossibility of simulating from a negative density. Not that we had high expectations of solving in a single afternoon an NP hard problem, and one of the major unsolved problems in the physics of many-particle systems… Although Mark had made the “mistake” of picking a Monday for his visit, reducing considerably the potential for wine bars and great restaurants in the area, we undertook to play Russian roulette with sea-shells, at a brasserie in the shadow of Alésia church, without any of us being hit by a bacterial bullet. (Mark then played the Parisian roulette by biking back to the north of Paris and his hotel, again managing to foil the automotive bullet!)