Saturday, August 01, 2020

Ramanan on Seshadri

CS Seshadri (1932-2020): World-class algebraic geometer, institution-builder and music lover
The author S. Ramanan was big influence on me when I joined TIFR in 1964. He (and M.S. Raghunathan) taught me several topics informally, sometimes during nights, and started an year long seminar for my benefit. He knew lot of mathematics in which he did not work and was a treasure to people around. I remember his insistence on canonical or natural thinking about mathematics. He is also one of those people who does not seem to have aged at all.
P.S. Raghunathan-Ramanan style: Once in a while, they would barge in to my office and ask something like ‘Do you know Peter-Weyl Theorem’. If I said no, they would say that everybody should know, start from scratch, develop the theory and prove the theorem.
Once I and Raghunathan were struggling to construct an inverse object in some K-group of projective modules with nilPotent endomorohisms. Ramanan came along ( this was around 1966-67) and suggested to look at the natural such object and map it on to our object in the obvious way.  The kernel was the inverse. The construction also led to a proof that any object representing the trivial element can be made trivial by elementary operations which can be easily imitated topologically.

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