Conference in honour of Arthur Ogus

A. Ogus is a professor at the University of California in Berkeley, where he was also Chairman of the Department of Mathematics from 2012 to 2015. He has been invited to IHES on numerous occasions: the first being in 1974, the most important in 1977-1978 and the most recent from September to December 2015. He has also been invited by a number of French universities, including Université Paris-Sud (Orsay) in 1978-1979 and in 1991. His area of research lies at the intersection of arithmetic and algebraic geometry. Many of his ideas, following the themes developed by A. Grothendieck and his colleagues found a natural home in France – at IHES in particular – where they were introduced, appreciated and discussed. Among the resulting long-lasting working partnerships in which A. Ogus was involved, the work undertaken with P. Berthelot from the early 1970s should be mentioned, together with the now classic publications that accompanied it: an introductory monography on crystalline cohomology (1978) and the article on the comparison between crystalline cohomology and De Rham cohomology (1983).

More recently, his interest in logarithmic geometry prompted by L. Illusie, A. Ogus has become one of its leading exerts and his hotly anticipated book on the topic is likely to also become a reference text.Those are just two examples of the strong links IHES has contributed to develop over the years between A. Ogus and some of the finest representatives of arithmetic geometry in the French mathematical school.