Department of

Mathematics


Seminar Calendar
for events the day of Monday, May 13, 2019.

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Monday, May 13, 2019

3:00 pm in 243 Altgeld Hall,Monday, May 13, 2019

Kirwan-Ness stratifications in algebraic geometry

Itziar Ochoa (Yale University)

Abstract: Given an algebraic variety $X$ with an action of a reductive group $G$, geometric invariant theory splits $X$ as the disjoint union $X=X^{ss}\sqcup X^{un}$ of the semistable and unstable locus. The Kirwan-Ness stratification refines $X$ even more by describing $X^{un}$ as a disjoint union of strata $X^{un}=\displaystyle\sqcup_{\beta\in\textsf{KN}} S_\beta$ determined by 1-parameter subgroups $\beta$. In this talk we will describe an algorithm that finds the $\beta$'s and show that such algorithm can be simplified when our space is of the form $T^*V$ where $V$ is a vector space.