# Definition:Generator of Monoid

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## Definition

Let $\left({M, \circ}\right)$ be a monoid

Let $S \subseteq M$.

Let $H$ be the smallest submonoid of $M$ such that $S \subseteq H$.

Then:

- $S$ is a
**generator**of $\left({H, \circ}\right)$ - $S$
**generates**$\left({H, \circ}\right)$ - $\left({H, \circ}\right)$ is the
**submonoid of $\left({M, \circ}\right)$ generated by $S$**.

This is written $H = \left\langle {S} \right\rangle$.

If $S$ is a singleton, i.e. $S = \left\{{x}\right\}$, then we can (and usually do) write $H = \left\langle {x}\right\rangle$ for $H = \left\langle {\left\{{x}\right\}}\right\rangle$.

## Also known as

Some sources refer to such an $S$ as a **set of generators** of $H$, but this terminology is misleading, as it can be interpreted to mean that each of the elements of $S$ is itself a generator of $H$ independently of the other elements.