Group of units of a monoid: Difference between revisions

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===In symbols===
===In symbols===


Let <math>M</math> be a monoid. Then <math>G=\{ m \in M: \exists n \in M: nm=e \}</math>. Then <math>G</math> is a group, the group of units of a monoid.
Let <math>M</math> be a [[monoid]]. Then <math>G=\{ m \in M: \exists n \in M: nm=e \}</math>. Then <math>G</math> is a [[group]], the '''group of units''' of a monoid.
 
==Examples==
 
One simple family of examples: The [[group of units modulo n]] is the group of units for the [[monoid of integers modulo n under multiplication]].

Latest revision as of 01:32, 12 January 2024

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Definition

In words

Given a monoid, its group of units is the set of all invertible elements in the monoid under the monoid's operation. It is indeed a group.

In symbols

Let M be a monoid. Then G={mM:nM:nm=e}. Then G is a group, the group of units of a monoid.

Examples

One simple family of examples: The group of units modulo n is the group of units for the monoid of integers modulo n under multiplication.