Monday 27 April 2026
14:30–16:00*

George Raptis (Aristotle University of Thessaloniki) — Scissors congruence K-theory of manifolds (and friends)

Scissors congruence K-theory of manifolds is a new K-theoretic framework for manifolds inspired by classical cut-and-paste (or SK-)invariants of manifolds. In this talk, I will first review the classical theory of SK-invariants, which provides a complete understanding of the equivalence classes of manifolds under cutting and pasting operations. I will then introduce (parametrized) scissors congruence K-theory as a (bivariant) K-theoretic refinement of the classical SK-groups, based on the recently developed formalism of squares K-theory. Finally, I will highlight some results and open questions concerning its relationship with cobordism categories and with the algebraic K-theory of spaces. (Based on joint work with M. Merling and J. Semikina.)

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