[[!redirects Sandbox > history]] [[!redirects Sandbox]] < [[nlab:Sandbox]] | | Modular numbers | Infinitesimals | |-|---------|------------------| | Base ring | $\mathbb{Z}$ | $\mathbb{R}[\epsilon]$ | | Field at prime | $\mathbb{Z}/p$ | $\mathbb{R}[\epsilon]/\epsilon \cong \mathbb{R}$ | | Weil algebra at prime power | $\mathbb{Z}/p^n$ | $\mathbb{R}[\epsilon]/\epsilon^n$ | | Topological completion | $\mathbb{Z}_{p}$ | $\mathbb{R}[[\epsilon]]$ | Shapes as types, to define extension types... category: redirected to nlab