# Centre for Complex Systems Events

**The Centre for Complex Systems** participates in, sponsors and hosts a number of events throughout the year.

Two of the Centre's major events programs are the C3 Symposia, and the C3 Research Camps.

## Upcoming Events for 2017

### Percolation, Cascades, and Control of Networks

**Date:** Monday 3 April 2017**Time:** 10:30am - 12pm**Venue:** Civil Eng J05 Conf Room 438**Presenter:** Prof. Raissa D'Souza**Bio:** Raissa D'Souza is Professor of Computer Science and of Mechanical Engineering at the University of California, Davis, as well as an External Professor at the Santa Fe Institute. She received a PhD in Statistical Physics from MIT in 1999, then was a postdoctoral fellow, first in Fundamental Mathematics and Theoretical Physics at Bell Laboratories, and then in the Theory Group at Microsoft Research. Her interdisciplinary work on network theory spans the fields of statistical physics, theoretical computer science and applied math, and has appeared in journals such as Science, PNAS, and Physical Review Letters. She is a Fellow of the American Physical Society, serves on the editorial board of numerous international mathematics and physics journals, has organized key scientific meetings like NetSci 2014, was a member of the World Economic Forum's Global Agenda Council on Complex Systems, and is currently the President of the Network Science Society.**Abstract:** Networks are at the core of modern society, spanning physical, biological and social systems. Each distinct network is typically a complex system, shaped by the collective action of individual agents and displaying emergent behaviors. Moreover, collections of these complex networks often interact and depend upon one another, which can lead to unanticipated consequences such as cascading failures and novel phase transitions. Simple mathematical models of networks, grounded in techniques from statistical physics, can provide important insights into such phenomena. Here we will cover several such models, beginning with control of phase transitions in an individual network and the novel classes of percolation phase transitions that result from repeated, small interventions intended to delay the transition. We will then move on to modeling phenomena in coupled networks, including cascading failures, catastrophe-hopping and optimal interdependence.

### Mathematical Aspects of Embodied Intelligence

**Date:** Wednesday 12 April 2017**Time:** 10:30am - 12pm**Venue:** Civil Eng J05 Conf Room 438**Presenter:** Prof. Nihat Ay**Bio:** Prof. Nihat Ay is Research Group Leader Information Theory of Cognitive Systems at Max Planck Institute for Mathematics in the Sciences, Honorary Professor at University of Leipzig, and Professor at the Santa Fe Institute.**Abstract:** I will present recent results on the design of embodied systems with concise control architectures, formalising the notion of "cheap design" within the field of embodied intelligence. This notion highlights the fact that high behavioural complexity, seen from the external observer perspective, does not necessarily imply high control complexity. This complexity gap is a result of two different frames of reference, which is closely related to Uexküll's Umwelt concept. If time allows, I will present a measure-theoretic formalisation of this concept and discuss its implications.

### Information Geometry and its Application to Complexity Theory

**Date:** Wednesday 19 April 2017**Time:** 2pm**Venue:** Carslaw Building, Access Grid Room, 8th floor**Presenter:** Prof. Nihat Ay**Bio:** Prof. Nihat Ay is Research Group Leader Information Theory of Cognitive Systems at Max Planck Institute for Mathematics in the Sciences, Honorary Professor at University of Leipzig, and Professor at the Santa Fe Institute.**Abstract:** In the first part of my talk, I will review information-geometric structures and highlight the important role of divergences. I will present a novel approach to canonical divergences which extends the classical definition and recovers, in particular, the well-known Kullback-Leibler divergence and its relation to the Fisher-Rao metric and the Amari-Chentsov tensor.

Divergences also play an important role within a geometric approach to complexity. This approach is based on the general understanding that the complexity of a system can be quantified as the extent to which it is more than the sum of its parts. In the second part of my talk, I will motivate this approach and review corresponding work.