Monday 23 February 2026
15:00–16:30*

Ronno Das (Lodha Mathematical Sciences Institute) — Rational curves on blowups

Inspired by Segal's work on rational functions and its many extensions, we show that the space of holomorphic maps from the Riemann sphere to certain blowups of projective space has homological stability as the degree gets large. Via the Grothendieck–Lefschetz trace formula and Katz–Milnor bounds on Betti numbers, we obtain a version of the Manin conjecture for degree 4 del Pezzo surfaces over finite fields. The talk will be based on joint work with Brian Lehmann, Sho Tanimoto and Philip Tosteson.

* Eastern European Time, i.e. UTC+2 in winter and UTC+3 in summer.