Our dear colleague Vladas Sidoravicius passed away unexpectedly on May 23, 2019, at the age of 55. Vladas was born in Vilnius, Lithuania in 1963. He did his undergraduate and masters studies from 1982 to 1986 at Vilnius University, where he received an Honor Diploma, and completed his PhD in Mathematics from Moscow University in 1990. After postdoctoral positions in the Netherlands and France, in 1993 he came to Brazil where he established himself as a leading scholar and spent over 20 years of his brilliant career, most of which at IMPA. In 2014, he was an Invited Speaker at the International Congress of Mathematicians. In 2015 he moved to China where he played a fundamental role in constructing a Probability group at NYU-Shanghai. He was the author of over 100 papers with many different co-authors.

Vladas was well known for his unique mathematical insights. “We first met in 1986 and started discussing possibilities for his research. I quickly realized that his mathematical mind and thinking was very unusual. He showed great imagination and geometric visualization of random processes. So I suggested him to go to Moscow for his PhD studies in a ‘modern probability’ related to statistical physics,” reports Donatas Surgailis. In the late 1990s, he became fascinated with questions involving percolation. “During his short appointment in São Paulo, we spent many hours discussing percolation problems, throwing ideas at each other, struggling to see them through. The playfulness of those interchanges is something I had never had before, and have not had ever since,” describes Luiz Renato Fontes. “During my doctorate, he was constantly teaching me how to think and speak of mathematics using intuition,” adds Renato dos Santos.

With 12 co-authored articles, he was the main collaborator of Harry Kesten. During a visit to Cornell in 1997, Vladas had an accident and his Achilles tendon was ruptured almost entirely. He was so focused on the discussions with Kesten that he neglected going to the doctor, and kept biking 6 miles a day for two weeks with a single leg. One of their most influential works finally appeared in the Annals of Mathematics, where they studied the spread of an infection in a moving population. This article accomplished a rare case of a Shape Theorem not relying on subadditivity.

During his career, Vladas has shown not only genuine talent for mathematical research, but also to gather people and interact with many fellow researchers. A milestone was to put together the outstanding event “Workshop in Mathematical Physics” in 2001. He had noticed a crucial moment of the area, with very important results coming out. His quick perception and the ability of gathering people led him to organize a truly cutting-edge event, bringing together the most prominent figures in the field.

Vladas was one of the initiators of the Brazilian Schools of Probability, with the first edition held in 1997. He brought here a number of other prestigious events, including: in 2006 the International Congress of Mathematical Physics and in 2010 the only Clay Summer School that ever took place in the country. “He was a big promoter of Latin American probability, and he could make the difference. I will miss him a lot, especially his warmth and positivity,” tells Alejandro Ramírez. “His contribution to Brazilian Probability in general is inestimable, but in the case of Belo Horizonte, it is easy to estimate: there would be no Probability group here were it not for him,” finalizes Bernardo de Lima. Four of his former students are currently based at UFMG.

Our community certainly remembers Vladas for his busy travel schedule and his passion for international collaboration. “Nobody knew where he was, and when least expected you would just bump into him somewhere around the globe. He was taking the pollen of creative mathematical thoughts from country to country, leading to unique breedings that often times yielded solutions to otherwise unsolvable problems,” remembers Leonardo Rolla.

Vladas was also known for his unique way of speaking Portuguese. “I will always remember how he would use the most unusual constructions and still convey an impressively detailed and precise image of the objects he wanted to describe,” says Marcelo Hilário. “Together with his other advisees and friends, we would often joke by mimicking his way of speaking, reproducing his unique expressions and usual grammar mistakes.” He did have a remarkably open and warm relationship with his advisees. “He knew how to be a good mentor, who cared not only about fostering scholarly abilities, but also the emotional skills of his young peers,” adds Manuel Cabezas. “In his office, I learned that a theorem can be proved in the middle of laughter, small talk, and amusement.”

“Someone with an acute sensibility, refined taste for music and fine arts, and for mathematics. A very keen curiosity for science in general. It is really sad that he left us so early. It was a gift to have met him,” concludes Maria Eulália Vares..

About the photos. The first and second photo were taken during a visit to Harry Kesten at Cornell University in 2003. The third one is the photo of the “Workshop in Mathematical Physics”, which took place at Mambucaba, Brazil, in 2001. The last one was taken in 2016 at NYU-Shanghai.