Celebratio Mathematica

I would like to share two short re­col­lec­tions from my time as a PhD stu­dent of Yasha’s.

I had the good for­tune of spend­ing the aca­dem­ic year 2009–10 in Berke­ley, for the MSRI pro­gram Sym­plect­ic and Con­tact Geo­metry and To­po­logy. It was an ex­cep­tion­al year, with many ex­perts in res­id­ence for ex­ten­ded peri­ods of time. In par­tic­u­lar, it gave stu­dents a fant­ast­ic op­por­tun­ity to broaden their back­ground in the field. Com­ing back from the In­sti­tute one even­ing, I fell off my bi­cycle in the UC Berke­ley cam­pus and had to get some stitches on my face. After re­cov­er­ing at home for a few days, I re­turned to MSRI one af­ter­noon to at­tend a talk by Yasha in the main aud­it­or­i­um. I ar­rived a little late, hop­ing to avoid say­ing much about the large band­ages on my face. As I walked in, Yasha saw me and im­me­di­ately in­ter­rup­ted his talk to say something like: “Hi Luís, wel­come. It is very ap­pro­pri­ate that you are here, since the sub­ject for today is sur­gery!”

On an­oth­er oc­ca­sion, dur­ing a break at some con­fer­ence, Yasha was talk­ing to Vikt­or Gin­zburg. I ap­proached them and Yasha dir­ectly in­cluded me in the con­ver­sa­tion, speak­ing to me in Rus­si­an. When he saw my puzzled face and re­called that I did not speak the lan­guage, he turned to Vikt­or and said (in Eng­lish): “Can you be­lieve this? He has been my stu­dent for 4 years and still does not speak Rus­si­an!”

These an­ec­dotes il­lus­trate Yasha’s ef­fort­less hu­mor, which he puts to bril­liant use in help­ing people (par­tic­u­larly his stu­dents) de­fuse the oc­ca­sion­al anxi­ety that might arise from work­ing in a hard, broad and some­times over­whelm­ing sub­ject like sym­plect­ic geo­metry. I find Yasha to be a con­stant source of in­spir­a­tion as a math­em­atician and as a kind per­son, and I feel ex­tremely priv­ileged for hav­ing had him as my PhD ad­visor.

Luís Diogo com­pleted his PhD from Stan­ford Uni­versity in 2012 un­der Yasha’s su­per­vi­sion. He was a postdoc at ETH Zürich, Columbia Uni­versity and Uppsala Uni­versity. He was an as­sist­ant pro­fess­or at Uni­ver­sid­ade Fed­er­al Flu­min­ense (Brazil), and is now an as­so­ci­ate pro­fess­or at Uppsala Uni­versity in Sweden.