Celebratio Mathematica

Thomas Milton Liggett

Memories: Tom Liggett

by Shannon Starr

I am grate­ful to be able to re­call fond memor­ies of time I spent at UCLA when I got to know Tom Lig­gett. I was a vis­it­ing re­search as­sist­ant pro­fess­or in 2005 and 2006. I in­ter­ac­ted with the prob­ab­il­ity group led by Tom, Marek Biskup, Lin­coln Chayes and Roberto Schon­mann. The postdocs in the group were Yev­gen­iy Kovchegov and Noam Ber­ger.

Tom was the un­der­gradu­ate vice-chair and gave much good ad­vice in teach­ing. I re­mem­ber he men­tioned that he taught dur­ing the Vi­et­nam War, and if he would not bend the rules for grad­ing then, stu­dents could be as­sured that he would not do it any time else. I re­mem­ber that Tom dis­liked the idea of a draft for the mil­it­ary in Amer­ica. At that time, some folks thought the idea of a draft would make Amer­ic­ans take their en­tan­gle­ments in wars more ser­i­ously. But Tom thought the idea was un­eth­ic­al.

I re­mem­ber that I was in­ter­ested in B. F. Skin­ner at that time. Tom noted that many people had been in­ter­ested in him, but many years earli­er.

Tom was one of the most de­cent people I had the pleas­ure of meet­ing. His son was a school teach­er at the time. His daugh­ter was an or­dained min­is­ter. He in­vited the group to his house for a party and I had a won­der­ful con­ver­sa­tion with her.

Tom gave a course on in­ter­act­ing particle pro­cesses. At the end Lin­coln sug­ges­ted we all bring in our text­books and Tom would sign them. I still have mine. It is a cher­ished pos­ses­sion.

I saw Tom after those years, too. He de­scribed his work with Pietro Cap­uto and Thomas Rich­tham­mer on a proof of an in­ter­est­ing con­jec­ture by Dav­id Al­dous for the spec­tral gap of the simple ex­clu­sion pro­cess on any fi­nite graph. He said the col­lab­or­a­tion was like the Bor­romean rings: if you re­move the con­tri­bu­tion of any one, the oth­er two would not hold to­geth­er. It was an es­sen­tial com­bin­a­tion of all three to­geth­er.

Shan­non Starr is As­so­ci­ate Pro­fess­or of Math­em­at­ics at the Uni­versity of Alabama.