Celebratio Mathematica

One could say that Lou van den Dries eats, sleeps, and breathes math­em­at­ics. However, Lou’s reg­u­lar pres­ence at cof­fee shops must be con­sidered, so “drinks” should be ad­ded to the list. As Lou’s first Ph.D. stu­dent, I quickly learned that the way to meet and dis­cuss math­em­at­ics with Lou was over es­presso.

Wheth­er at a cof­fee shop or else­where, Lou is one of the nicest people around. He fits in well with the friendly group of lo­gi­cians at the Uni­versity of Illinois (UIUC), and has a good sense of hu­mor, evid­ent in his will­ing­ness to laugh at him­self when he can­not find the keys that are in his hand or loc­ate the top of his desk, bur­ied deep un­der piles of pa­pers and books. Lou’s col­leagues en­joy these laughs with him, but also par­tic­u­larly en­joy Lou’s keen math­em­at­ic­al in­tel­li­gence.

A not­able trait of Lou’s is his at­ten­tion to de­tail. Be­sides be­ing a valu­able trait for math­em­at­ics, this fo­cus can even be a source of hu­mor. One day in class, Lou was filling up the black­board while we stu­dents tried to keep up. As we were scrib­bling di­li­gently in our notes, Lou paused. He re­marked that he needed a let­ter for the next vari­able, but that the re­main­ing avail­able let­ters would break the pat­tern of al­pha­bet­ic­al or­der. The next thing we knew, Lou was eras­ing all of the vari­ables on the black­board and writ­ing new let­ters, much to the as­ton­ish­ment of us stu­dents as we scrambled to catch all of the changes and puzzle over the mess of our notes.

The at­ten­tion to de­tail is one reas­on that Lou has ac­com­plished so much in math­em­at­ics. It is also one reas­on that Lou’s writ­ing in Eng­lish, which is not his first lan­guage, is bet­ter than that of most nat­ive Eng­lish speak­ers. It also hap­pens to be the reas­on why oc­ca­sion­ally, dur­ing a sem­in­ar, Lou will ask an in­cred­ibly simple ques­tion, start­ling his col­leagues in­to won­der­ing wheth­er he has sud­denly lost his in­tel­lect. As it turns out, all of his fac­ulties are quite in­tact: Lou has tripped over an am­bi­gu­ity, or per­haps an ex­tra comma, that oth­er par­ti­cipants did not even no­tice. Once the amus­ing con­fu­sion is cleared up, it be­comes evid­ent that Lou is really on top of things, far more so than most people in the audi­ence.

Lou’s en­thu­si­asm for math­em­at­ics also leaves room for oth­er in­terests and ad­ven­tures. He was al­ways up for “lo­gic lunch” at UIUC, a hike at a con­fer­ence, or a soc­cer game. If you were on the op­pos­ing soc­cer team, you had to watch out for his sur­pris­ingly good soc­cer skills.

People who have crossed paths with Lou van den Dries have had their lives en­riched and up­lif­ted by their in­ter­ac­tions with him. Al­though I changed math­em­at­ic­al fields after com­plet­ing the Ph.D. in or­der to pur­sue op­por­tun­it­ies near moun­tains (the ter­rain for great ski­ing and hik­ing!), I highly en­joyed math­em­at­ics with Lou through many in­triguing dis­cus­sions about o-min­im­al struc­tures, thought­ful ex­plor­a­tions of tor­sion-free mod­ules, and cheer­ful de­bates about al­geb­ra­icaly closed value fields. I also re­call, be­sides math­em­at­ics and cof­fee shops, quite a few ex­cit­ing soc­cer games on alert for Lou and his quick moves as he sprin­ted up the field around his sur­prised op­pon­ents.