[Haskell-cafe] Is there a name for this property: x + x - x == x

Ezequiel Alvarez welcometothechango at gmail.com
Wed Jun 4 14:46:02 UTC 2014


Exactly, it's 3 properties: associativity, inverse and identity.


On Wed, Jun 4, 2014 at 11:42 AM, David Thomas <davidleothomas at gmail.com>
wrote:

> If you have associativity, this seems roughly the same as saying there
> is an additive inverse for every x, because x + x - x = x => x + (x -
> x) = x => x + 0 = x.
>
> On Wed, Jun 4, 2014 at 7:34 AM, Omari Norman <omari at smileystation.com>
> wrote:
> > It's not quite idempotence, because more than one function is involved.
> >
> > It's a common property and I figure I can write a higher order function
> to
> > build QuickCheck tests for it.  I was just wondering if it has a name.
> >
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