English

The $\mathbb{A}^1$-Euler characteristic of symmetric powers

Algebraic Geometry 2026-01-13 v2

Abstract

The A1\mathbb{A}^1-Euler characteristic is a refinement in algebraic geometry of the classical topological Euler characteristic, which can be constructed using motivic homotopy theory. This invariant is a quadratic form rather than an integer, which carries a lot of information, but is difficult to compute in practice. In this survey, we discuss a conjectural way for computing the A1\mathbb{A}^1-Euler characteristic of the symmetric powers of a variety in terms of the A1\mathbb{A}^1-Euler characteristic of the variety itself formulated using the theory of power structures. We discuss evidence towards the conjecture so far, techniques to approach it, and applications.

Keywords

Cite

@article{arxiv.2510.06922,
  title  = {The $\mathbb{A}^1$-Euler characteristic of symmetric powers},
  author = {Louisa F. Bröring and Jesse Pajwani and Anna M. Viergever},
  journal= {arXiv preprint arXiv:2510.06922},
  year   = {2026}
}

Comments

19 pages. Survey article written for the conference volume of the IAS PCMI 2024 summer session. Minor revisions. Comments welcome!

R2 v1 2026-07-01T06:23:37.921Z