Definition:Generator of Module

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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 every element of $M$ is a linear combination of elements of $S$.


Definition 2

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


Definition 3

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


Generated Submodule

Definition 1

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


Definition 2

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.


Also see