学术报告（12月28日）

主持人：张笑 教授

欢迎广大师生踊跃参加！

报告摘要：
I shall describe a simple model of phase transitions in complex networks that has the aesthetic appeal of decision making with heterogeneous, interacting agents deciding between two or more choices. Each agent picks the choice with the highest sum of “intrinsic” utility, which does not depend on his/her network, and “social” utility, which depends on his/her neighbors on the social graph. For a special class of interactions, this model is the mean-field description of random field Potts-like models and is effectively solved by finding the extrema of the average energy per agent. In these cases, by studying the propagation of decision changes via avalanches (phase transitions), I argue that macroscopic dynamics is well captured by a gradient flow along the energy landscape. As examples, I show that bimodal heterogeneity naturally provides a mechanism for the spontaneous formation of hierarchies between decisions and that spontaneous symmetry breaking is a preferred instability to discontinuous phase transitions between two symmetric points. Beyond the mean field limit, exponentially many stable equilibria emerge. I shall emphasize on the interesting analogies between my model and common intuition from diverse areas of physics, including statistical physics and electromagnetism. This talk is based on the works "Simple model for multiple-choice collective decision making", Physical Review E 90.5 (2014): 052804 and “Multistable binary decision making on networks”, Physical Review E 87.3 (2013): 032806.

报告人简介：
Dr. Ching Hua Lee is currently a Research Scientist at Singapore Institute of High Performance Computing. He received his PhD at Stanford University. He research interests include N=8 super Yang-Mills theory, topological insulators, multicomponent fractional quantum hall systems, holography, complex networks and decision-making.