Identity element

Given a magma $(M,*)$ , an element $e$ is an identity element if, for all $x$ in $M$ ,
$e*x=x*e=x.$ Forcefully, if an identity element exists, it has to be unique.

Remarks

A magma with an identity element is called unital magma.

Practice this concept with exercises

1 / 2

Let $(M,*)$ be a unital magma with identity element $e$ . Show that $e$ is unique.

Open exercise

Problems using this concept (0)

No listed problems link to this concept yet.

Problems using this concept (spoiler) (0)

No listed problems use this concept as a spoiler yet.