Peter Ladislaw Hammer

Peter Ladislaw Hammer was born in Timisoara, Romania in 1936. He earned his Ph.D. under Academician Grigore Moisil at the University of Bucharest. After he married Anca Ivanescu in 1961, the two defected to Israel in 1967. There, he was a professor at the Technion in Haifa. After moving to Canada in 1969, he taught at the University of Montreal, then later at the University of Waterloo. In 1983 he moved to the US and became a professor at Rutgers University.

Dr. Hammer was the founding Director of RUTCOR - Rutgers University Center for Operations Research, Editor-in-Chief and founder of numerous professional journals, including Discrete Mathematics, Discrete Applied Mathematics, Discrete Optimization, Annals of Discrete Mathematics, Annals of Operations Research and the SIAM Monographs on Discrete Mathematics and Applications. His publications include 19 books and over 240 papers.

He was one of the most influential researchers in the fields of Operations Research and Discrete Applied Mathematics. He made numerous major contributions to these fields, launching several new research directions. His results influenced hundreds of colleagues in discrete mathematics and operations research, and made a lasting impact on several areas, including binary optimization and algorithmic graph theory. His landmark book on Boolean Methods in Operations Research and Related Areas (co-authored with S. Rudeanu, Springer-Verlag, 1968) founded the new area of pseudo-Boolean optimization.

His systematic approach to study the combinatorial structure of Boolean functions, and their role in and relationship to optimization problems developed a whole new Theory of Boolean Functions (a book about this field, co-edited and co-authored with Y. Crama, is forthcoming from Cambridge University Press, 2007). He applied in novel ways Boolean techniques to other areas, including graph theory, integer programming, data analysis, just to mention a few. His application of such Boolean techniques to data analysis proved to be particularly novel and effective. The technique, called Logical Analysis of Data (LAD), was successfully applied to several real-life data analysis problems, including in the last few years numerous medical datasets.

Dr. Hammer contributed to and promoted the field of Operations Research in several different ways. Besides his mathematical results, books and papers, he launched series of professional publications, and was a relentless organizer of professional conferences and workshops. He always made sure that these events and forums provided opportunities for interactions, in particular for younger researchers. He created the research center RUTCOR also as an open institution, where seminars, workshops, graduate courses, and a constant flow of visiting colleagues create a buzzing research environment.

Dr. Hammer was internationally recognized as a leading researcher of Operations Research and modern Discrete Applied Mathematics. He received numerous distinctions, including honorary degrees from the Swiss Federal Institute of Technology in Lausanne (1986), University of Rome "La Sapienza" (1998), University of Liege (1999), the "George Tzitzeica" prize of the Romanian Academy of Science (1966), and the Euler Medal of the Institute of Combinatorics and its Applications (1999). He was a Fellow of the American Association for the Advancement of Science from 1974, and a Founding Fellow of the Institute of Combinatorics and its Applications. Several conferences were dedicated to him, including the First International Colloquium on Pseudo-Boolean Optimization (Chexbres, Switzerland, 1987), the Workshop and Symposia Honoring Peter L. Hammer (Caesarea Rothchild Institute, University of Haifa, 2003) and the International Conference on Graphs and Optimization (GO V, Leukerbad, Switzerland, 2006).

Dr. Hammer was not only an amazing scholar and a tireless organizer, but also a very kind and generous person. He made everybody feel comfortable to work with him, let it be on mathematics or on planning a conference. He helped younger researchers and graduate students with good advice, supporting letters, or sometimes even with loans and presents. He supervised numerous graduate students with respect and fatherly understanding, considering each of them as his 'best student'.

One of his final lectures was entitled "Why not to turn 70" and subtitled "Problems left for my second and third lives". This exemplified not only his humor, but also his relentless energy.

He was a loving husband, father and grandfather. He is survived by his wife, Anca, his two sons Alexander and Maxim, his mother Anne, his sister Evi, brother-in-law Ghita, niece Dana, and daughters-in-law, Robin and Stacey, and his many cousins. His four beloved grandchildren, Isabelle, Madeline, Annelise, and Oliver, knew him as their dear "Api". He will be missed by everyone who knew him, always and forever.

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