UBC

Mon 18 Nov 2019, 3:00pm
Algebraic Geometry Seminar
MATH 225

Biregular Cremona transformations of the plane

MATH 225
Mon 18 Nov 2019, 3:00pm5:00pm
Abstract
We study the birational selfmaps of the projective plane that induce bijections on the krational points for a given field k. These form a subgroup BCr_2(k) inside the Cremona group. The elements of BCr_2(k) are called Biregular Cremona transformations. We show that BCr_2(k) is not finitelygenerated under a mild hypothesis on the field k. When k is a finite field, we study the possible permutations induced on the krational points of the plane. This is joint work with KuanWen Lai, Masahiro Nakahara and Susanna Zimmermann.
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UBC

Mon 25 Nov 2019, 3:00pm
Algebraic Geometry Seminar
MATH 225

Projective bundle formula in derived cobordism theory

MATH 225
Mon 25 Nov 2019, 3:00pm5:00pm
Abstract
I will introduce the universal precobordism theory, which generalizes algebraic cobordism of LevineMorel to arbitrary quasiprojective schemes over a Noetherian base ring A. In the main part of the talk I will outline the proof of projective bundle formula for this new cohomology theory. The usual proof techniques based on resolution of singularities and weak factorization break down in this generality, so we have to use an alternative approach based on carefully studying the structure of precobordism rings of varieties with line bundles, which were inspired by a paper of LeePandharipande. The talk is based on joint work with Shoji Yokura.
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UBC

Mon 2 Dec 2019, 3:00pm
Algebraic Geometry Seminar
MATH 225

TBA

MATH 225
Mon 2 Dec 2019, 3:00pm5:00pm
Abstract
TBA
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