English

$\mathbb A^1$-connected components of affine quadrics

Algebraic Geometry 2026-01-29 v1

Abstract

For any smooth quadratic hypersurface XX in Akn\mathbb A^n_k, we use the iterations of the functor of naive A1\mathbb{A}^1-connected components S\mathcal{S} to study the field-valued sections of the sheaf of A1\mathbb{A}^1-connected components π0A1(X)\pi_0^{\mathbb{A}^1}(X) of XX. We prove that for any field F/kF/k, the canonical isomorphism π0A1(X)(F)limnSn(X)(F)\pi_0^{\mathbb{A}^1}(X)(F) \xrightarrow{\sim} \lim_{n} \mathcal{S}^n(X)(F) stabilizes at n=2n=2, meaning that π0A1(X)(F)=S2(X)(F)\pi_0^{\mathbb{A}^1}(X)(F)=\mathcal{S}^2(X)(F). Furthermore, by combining this result with Morel's characterization of A1\mathbb{A}^1-connected spaces in terms of the triviality of field-valued sections of π0A1\pi_0^{\mathbb{A}^1}, we provide a complete characterization of A1\mathbb{A}^1-connected smooth quadratic hypersurfaces in Akn\mathbb{A}^n_k.

Keywords

Cite

@article{arxiv.2601.20593,
  title  = {$\mathbb A^1$-connected components of affine quadrics},
  author = {Chetan Balwe and Nidhi Gupta},
  journal= {arXiv preprint arXiv:2601.20593},
  year   = {2026}
}

Comments

28 pages, comments are welcome

R2 v1 2026-07-01T09:23:55.973Z