Triangle Seminars
Tuesday, 30 Mar 2010
Evolutionary games on structured populations
Christoforos Hadjichrysanthou
(City University)
Abstract:
Evolutionary dynamics models have been mainly studied on homogeneous infinite populations. However, real populations are neither homogeneously mixed nor infinite. We investigate the stochastic evolutionary game dynamics on structured populations represented by graphs. We consider three simple graphs of finite number of vertices: the star, the circle and the complete graph. We present exact formulae for the fixation probability of a single mutant individual introduced into the graph and the speed of the evolutionary process, namely the mean time to absorption (either mutant fixation or extinction) and the mean time to mutant fixation. Through numerical examples we show the significant impact of the structure of the population, the population size and the payoff matrix on the above quantities.
Evolutionary dynamics models have been mainly studied on homogeneous infinite populations. However, real populations are neither homogeneously mixed nor infinite. We investigate the stochastic evolutionary game dynamics on structured populations represented by graphs. We consider three simple graphs of finite number of vertices: the star, the circle and the complete graph. We present exact formulae for the fixation probability of a single mutant individual introduced into the graph and the speed of the evolutionary process, namely the mean time to absorption (either mutant fixation or extinction) and the mean time to mutant fixation. Through numerical examples we show the significant impact of the structure of the population, the population size and the payoff matrix on the above quantities.
Posted by: KCL
Thursday, 1 Apr 2010
Extremal black holes: a status report
Joan Simon
(Edinburgh)
Abstract:
I will review some recent attempts at providing a microscopic description
for extremal black holes. First, I will explain a constituent model for extremal non-rotating non-BPS asymptoticaly flat black holes. Second,
I will summarise the main claims in the so called extremal BH/CFT
correspondence, pointing out how a chiral CFT can emerge as a limit
of a non-chiral CFT. Finally, I will use R-charge AdS black holes
to derive the existence of emergent IR CFTs, similar to the ones
that have been argued to capture some interesting quantum criticality
phenomena in some strongly coupled condensed matter systems.
I will review some recent attempts at providing a microscopic description
for extremal black holes. First, I will explain a constituent model for extremal non-rotating non-BPS asymptoticaly flat black holes. Second,
I will summarise the main claims in the so called extremal BH/CFT
correspondence, pointing out how a chiral CFT can emerge as a limit
of a non-chiral CFT. Finally, I will use R-charge AdS black holes
to derive the existence of emergent IR CFTs, similar to the ones
that have been argued to capture some interesting quantum criticality
phenomena in some strongly coupled condensed matter systems.
Posted by: QMW