Smooth affine group schemes over the dual numbers
Abstrak
We provide an equivalence between the category of affine, smooth group schemes over the ring of generalized dual numbers $k[I]$, and the category of extensions of the form $1 \to \text{Lie}(G, I) \to E \to G \to 1$ where G is an affine, smooth group scheme over k. Here k is an arbitrary commutative ring and $k[I] = k \oplus I$ with $I^2 = 0$. The equivalence is given by Weil restriction, and we provide a quasi-inverse which we call Weil extension. It is compatible with the exact structures and the $\mathbb{O}_k$-module stack structures on both categories. Our constructions rely on the use of the group algebra scheme of an affine group scheme; we introduce this object and establish its main properties. As an application, we establish a Dieudonné classification for smooth, commutative, unipotent group schemes over $k[I]$.
Topik & Kata Kunci
Penulis (2)
Matthieu ROMAGNY
Dajano Tossici
Akses Cepat
- Tahun Terbit
- 2019
- Sumber Database
- DOAJ
- DOI
- 10.46298/epiga.2019.volume3.4792
- Akses
- Open Access ✓