Ulam, the man and the mathematician
Paul L. Erdos · Journal of Graph Theory · 1985
First of all a few words of introduction. Ulam was a friend and collaborator of mine for about 50 years. We had innumerable mathematical and political discussions and have several joint papers. While discussing mostly our joint work I will neglect his work in physics, biology, computers and computer science. Ulam wrote a very successful autobiography [71 and I will mention only a few incidents which as far as I remember are not mentioned in his autobiography and which I hope are accurate. I first met Ulam in Cambridge, England in 1935 and then again in 1938-39 in Cambridge, Massachusetts at Harvard University where he was a member of the Society of Fellows. But our real mathematical contact started when I visited him twice at the University of Wisconsin between 1941 and 1943 and where we obtained our first joint results. Then I met him in Santa Fe and Los Angeles in 1946. He had a serious illness there (almost his only illness, he enjoyed very good health up to his fatal heart attack), probably encephalitis. He completely