Speaker: 陈伟彦，清华大学   

Inviter: 陈蕾 副研究员

Title: Topological complexity of enumerative problems and classifying spaces of PU_n

Language: Chinese 

Time & Venue: 2024.11.13 14:30-15:30 N818

Abstract: We study the topological complexity, in the sense of Smale, of three enumerative problems in algebraic geometry: finding the 27 lines on cubic surfaces, the 28 bitangents and the 24 inflection points on quartic curves. In particular, we prove lower bounds for the topological complexity of any algorithm solving the three problems and for the Schwarz genera of their associated covers. The key is to understand certain cohomology classes of the classifying spaces of the projective unitary groups PU_n. This work is joint with Xing Gu.