Professor Lasota is a mathematician of the first rank. Mathematics describes the world promarily through 2 fields of mathematics: (1) dynamical system and differential equations and (2) probability theoty and statistics. Professor Lasota finds the pure mathematics in the boundary between those 2 to tell the scientists how to view the world. Further, I would like to now dscribe what I believe is perhaps his best result. Throughout the 20th century, people had descibed a variety of measures that are invariant under dynamical systems. Professor Lasota was interested in those invariant measures on attractors, which had never been done before. By an attractor I mean a proper subset of some larger space. When he visited the Univerity of Maryland in 1961, he had his whole philosophy and methods worked out for 1 dimensional dynamical systems. I was fortunate to be able to learn from him and help with the detailed inequalities.

Nonlinear Dynamics is the theory of how systems or devices or objects evolve in time. It is central to virtually every science. His Revolutionary approach was to select a probability measure for an initial point x__0 of the dynamics and examine the probability distributions of the trajectory x_1, x_2, ... .As the trajectory converges, the average of the probability distributions converges to an invariant measure. This approach was adopted by the Berkeley school of dynamics and became one of the foundations of nonlinear dynamics. Professor Lasota's broad view of nonlinear dynamics and his keen insights and powerfull methods have resulted in his work being of great importance in nonlinear dynamics.

I am happy tomprovide this letter of support on behalf of Ptofessor Lasota for an honorary degree at your university, and enthusiastically recommend him for this honor.

James A. Yorke
Distinguished Univerity Professor of Physics and Mathematics
University of Maryland