Texas A&M University, Department of Mathematics, 216 Milner Hall, 10th of October 2007, 3:00-3:50

Groups and Dynamics Seminar


Of random time delays, rabbits, and the visible points of the integer lettuce

Tamás Kalmár-Nagy of Texas A&M University

The salient feature of today's ubiquitous embedded systems is the coupling of dynamic components via the underlying communication network. Developing a theoretical and computational framework for stability analysis for systems with random time delays (due to the communication) is therefore of great theoretical and practical importance. Motivated by this need, the author started to investigate digital control systems with random time delays. This problem gives rise to discrete-time jump linear systems, where the transition jumps are modeled with an underlying finite-state Markov chain. One of the simplest, non-trivial such model is the so-called random Fibonacci sequence. This is a second-order difference equation where the coefficient matrix is randomly chosen (from a set of two integer valued matrices) at every time step. In this presentation we show some beautiful and far-reaching connections between the random Fibonacci recurrence, the visible points of the plane, a random walk on the induced self-similar graph and generalized Catalan numbers.