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On the infinite loop spaces of algebraic cobordism and the motivic sphere

Tom Bachmann, Elden Elmanto, Marc Hoyois, Adeel A. Khan, Vladimir Sosnilo, Maria Yakerson

Abstract

We obtain geometric models for the infinite loop spaces of the motivic spectra $\mathrm{MGL}$, $\mathrm{MSL}$, and $\mathbf{1}$ over a field. They are motivically equivalent to $\mathbb{Z}\times \mathrm{Hilb}_\infty^\mathrm{lci}(\mathbb{A}^\infty)^+$, $\mathbb{Z}\times \mathrm{Hilb}_\infty^\mathrm{or}(\mathbb{A}^\infty)^+$, and $\mathbb{Z}\times \mathrm{Hilb}_\infty^\mathrm{fr}(\mathbb{A}^\infty)^+$, respectively, where $\mathrm{Hilb}_d^\mathrm{lci}(\mathbb{A}^n)$ (resp. $\mathrm{Hilb}_d^\mathrm{or}(\mathbb{A}^n)$, $\mathrm{Hilb}_d^\mathrm{fr}(\mathbb{A}^n)$) is the Hilbert scheme of lci points (resp. oriented points, framed points) of degree $d$ in $\mathbb{A}^n$, and $+$ is Quillen's plus construction. Moreover, we show that the plus construction is redundant in positive characteristic.

On the infinite loop spaces of algebraic cobordism and the motivic sphere

Abstract

We obtain geometric models for the infinite loop spaces of the motivic spectra , , and over a field. They are motivically equivalent to , , and , respectively, where (resp. , ) is the Hilbert scheme of lci points (resp. oriented points, framed points) of degree in , and is Quillen's plus construction. Moreover, we show that the plus construction is redundant in positive characteristic.

Paper Structure

This paper contains 5 sections, 21 theorems, 37 equations.

Key Result

Theorem 1.1

Let $k$ be a field. Then there is an equivalence in $\mathbf{H}(k)$, where $+$ denotes Quillen's plus construction (in the $\infty$-topos of Nisnevich sheaves). Moreover, there is an equivalence If $k$ has positive characteristic, the same equivalences hold without the plus construction.

Theorems & Definitions (45)

  • Theorem 1.1
  • Theorem 1.2
  • Remark 1.3
  • Theorem 1.4
  • Theorem 1.5
  • Conjecture 1.6: M. Hopkins
  • Corollary 1.7
  • Remark 1.8
  • Lemma 2.1
  • proof
  • ...and 35 more