Professor Arie Leizarowitz of the Technion Department of Mathematics passed away on Saturday morning, July 10th 2010. He was a recognized leader in control theory and optimization.

Arie was born April 26th, 1953 in Tel Aviv. After obtaining the B.Sc degree in Physics from Tel Aviv University he went on to serve as an officer at the Israeli air force. He completed his M.Sc studies in Applied Mathematics at Tel Aviv University in 1980, and in 1984 he obtained his Ph.D in Mathematics from the Weizmann Institute under the guidance of Professor Zvi Artstein.

Arie used his prestigious Weizamann Fellowship to spend two years at the Institute for Mathematics and its Applications at the University of Minnesota. The Institute was established in the same year attracted outstanding researchers and postdoctorate fellows and served as a great "incubator" for young researchers. This was followed by a two years appointment as a Zeev Nehari Assistant Professor at Carnegie Mellon University. In 1988 Arie joined the Technion, where he was promoted in 2005 to the rank of full professor.

The main area of Arie's research was deterministic and stochastic control theory and in particular control with infinite horizon. He also made significant contributions to calculus of variations, optimization, and partial differential equations. His work was not limited to pure staff. He was interested in modeling and in applying math to real world problems. For instance, he wrote several papers on neural networks and on the management of aquifers. He published about 60 research papers in top journals, and one monograph, with A. Haurie and D. Carlson, that became the standard text on infinite horizon optimal control.

A workshop on "Variational and Optimal Control Problems on Unbounded Domains" dedicated to the memory of Arie and sponsored by the Israel Science Foundation was held at the Technion under the auspices of the CMS on January 2012. The workshop brought together many prominent mathematicians from all over the world and was devoted to many aspects of Arie's achievements.

Known among his friends and colleagues as a fearless mathematician, he attacked in recent years some of the most outstanding problems in optimization and even in number theory. He was a brilliant mathematician, yet a modest man and dedicated teacher, loved and appreciated by his colleagues and students. Arie was broad-minded and has an infinite horizon, he loved to talk eye to eye on every issue with anyone, but most of all he loved having a conversation with a mathematician. Then he was in a hurry to shift the conversation and share with his interlocutor details of mathematical problems that plagued him at that time.

Arie captured every one with his pleasant facial expression, warm smile, kindness, simplicity manners, honesty and generosity. Arie was a timid man, with no posing and no gigs.

He was very fond of music and played since his teenage years the accordion and the piano.

Arie was an exemplary family man. Loving and beloved father, devoted to his family, proud and attached to it with all his heart and soul. Arie is survived by his wife Natty and children Noa and Avishai.

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