2014 Robert Stewart Distinguished Lecture Thursday May 1, 2014 - 3:40pm Luca Cardelli Howe Hall Alliant Energy Microsoft Research Cambridge http://lucacardelli.name/ Lee Liu Auditorium The Cell Cycle Switch Computes Approximate Majority Biological systems have been traditionally, and quite successfully, studied as ‘dynamical systems’, that is, as continuous systems defined by differential equation and investigated by sophisticated analysis of their continuous state space. More recently, in order to cope with the combinatorial complexity of some of these systems, they have been modeled as ‘reactive systems’, that is, as discrete systems defined by their patterns of interactions and investigated by techniques that come from software and hardware analysis. There are growing formal connections being developed between those approaches, and tools and techniques that span both. The two approaches can be usefully combined to bring new insights to specific systems. In one direction we can ask ‘what algorithm does a dynamical system implement’ and in the opposite direction we can ask ‘what is the dynamics of a reactive system as a whole’. Answers to these questions can establish links between the structure of a system, which is dictated by the algorithm it implements, and the function of the system, which is represented by its dynamic behavior. Since there is depth on both sides, in the intricacies of the algorithms, and in the complexity of the dynamics, a better understanding can emerge of whole systems. I will focus in particular on a connection between a clever and well-studied distributed computing algorithm, and a simple chemical system (4 reactions). It leads to a connection between that algorithm and a well-known biological switch that is universally found as part of cell cycle oscillators. These connections are examples of ‘network morphisms’ that preserve both structure and functionality across systems of different complexity. ABOUT LUCA CARDELLI Luca Cardelli is a Principal Researcher at Microsoft Research Cambridge. He heads the Programming Principles and Tools Group and his main interests are in type theory and operational semantics, mostly for applications to language design and distributed computing. Currently he is working in Computational Systems Biology. Luca implemented the first compiler for ML (the most popular typed functional language) and one of the earliest direct-manipulation user-interface editors. He was a member of the Modula-3 design committee and has designed a few experimental languges, of which the latest are Obliq, a distributed higher-order scripting language, and Polyphonic C#, an object-oriented language with modern concurrency abstractions. His more protracted research activity has been in establishing the semantic and type-theoretic foundations of object-oriented languages. The Robert Stewart Distinguished Lecture in Computer Science is made possible by the generous contribution of Dr. Long Nguyen, who received his doctorate from the ISU Computer Science Department in 1975. It is in honor of his mentor, Dr. Robert Stewart, Professor Emeritus and the first Department Chair of Computer Science at Iowa State University..