# Definition:Generator of Module

## Definition

Let $R$ be a ring.

Let $M$ be an $R$-module.

Let $S \subseteq M$ be a subset.

### Definition 1

$S$ is a generator of $M$ if and only if $M$ is the submodule generated by $S$.

### Definition 2

$S$ is a generator of $M$ if and only if $M$ has no proper submodule containing $S$.

## Generator of Unitary Module

Let $R$ be a ring with unity.

Let $M$ be a unitary $R$-module.

Let $S \subseteq M$ be a subset.

$S$ is a generator of $M$ if and only if every element of $M$ is a linear combination of elements of $S$.

## Generated Submodule

Let $R$ be a ring.

Let $M$ be an $R$-module.

Let $S \subseteq M$ be a subset.

### $R$-module

The submodule generated by $S$ is the intersection of all submodules of $M$ containing $S$.

### Unitary $R$-Module

Let $R$ be a ring with unity.

Let $M$ be a unitary $R$-module.

The submodule generated by $S$ is the set of all linear combinations of elements of $S$.

## Also known as

A generator of a module is also known as a spanning set.

Some sources refer to a generator for rather than generator of. The two terms mean the same.

It can also be said that $S$ generates $M$ (over $R$).

Other terms for $S$ are:

• A generating set of $M$ (over $R$)
• A generating system of $M$ (over $R$)

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