Definition:Associate/Integral Domain

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Definition

Let $\struct {D, +, \circ}$ be an integral domain.

Let $x, y \in D$.


Definition 1

$x$ is an associate of $y$ (in $D$) if and only if they are both divisors of each other.

That is, $x$ and $y$ are associates (in $D$) if and only if $x \divides y$ and $y \divides x$.


Definition 2

$x$ and $y$ are associates (in $D$) if and only if:

$\ideal x = \ideal y$

where $\ideal x$ and $\ideal y$ denote the ideals generated by $x$ and $y$ respectively.


Definition 3

$x$ and $y$ are associates (in $D$) if and only if there exists a unit $u$ of $\struct {D, +, \circ}$ such that:

$y = u \circ x$

and consequently:

$x = u^{-1} \circ y$


That is, if and only if $x$ and $y$ are unit multiples of each other.


Also known as

The statement $x$ is an associate of $y$ can be expressed as $x$ is associated to $y$.


Also see

  • Results about associates can be found here.