nLab
unital magma

Contents

Contents

Definition

A magma (S,)(S,\cdot) is called unital if it has an identity element 1S1 \in S, hence an element such that for all xSx \in S it satisfies the equation

1x=x=x1 1 \cdot x = x = x \cdot 1

holds. The identity element is idempotent.

Some authors take a magma to be unital by default (cf. Borceux-Bourn Def. 1.2.1).

Examples

Examples include unital rings etc.

Last revised on January 26, 2020 at 02:00:39. See the history of this page for a list of all contributions to it.