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The Complexity of Symbolic Sequences

Speaker: Prof. Lock Yue Chew Nanyang Technological University
Time: 2015-04-16 15:30-2015-04-16 16:30
Venue: FIT 1-222


A basic question in the study of complex systems is: “what is complexity?” While there are many definitions of complexity, a concrete way to create a science of complexity is to provide a quantitative definition. Even this runs into trouble as there are at least 40 such definitions according to Prof Seth Lloyd of MIT in “Measures of Complexity – a non-exhaustive list”. In this talk, I will explore one of these measures of complexity known as the “statistical complexity”. This measure of complexity is defined and developed by Prof James Crutchfield of the University of California at Davis, and is made concrete through the idea of ε-machine. I will discuss on ε-machine and how we can use it to measure the complexity of diverse symbolic sequences. In particular, I will present on our recent results on the complexity of sequences generated by the arc-fractal systems, as well as those produced by the pseudo-random number generators.

Short Bio:

Dr Lock Yue Chew is an Associate Professor in Theoretical Physics in the Division of Physics and Applied Physics of the Nanyang Technological University (NTU). He is also an associate member of the newly established Complexity Institute in NTU. Dr Chew’s research interest is on the physics of complex systems. He aims to understand the fundamental mechanisms of complex systems through inter-disciplinary studies on biological, quantum and classical interacting systems by means of nonlinear and statistical physics. Recently, he had explored into questions on the characterization and measure of complexity; regime shifts and critical transitions in coupled social-ecological systems; and the evolution of complexity through information spreading and processing in networks of interacting agents.