Add class `Involutive`.
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Owner
Isn't it a bit strange to have a class with 0 instances in the library?
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Maintainer
I suppose we could add an instance for negation of integers?
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Owner
I was also about to suggest a relation to idempotency, which I thought was something like
f (f x) = f x
, but it doesn't seem like we have that? We work with such a function a lot though, it's called the core. (Well, things get more complicated because that can also be partial.)We only have
f x x = x
, which is an idempotent element of an operation, but not an idempotent operation. -
Maintainer
Looking at the other classes, isn't
Involutive R f
the same asCancel R f f
?Good point, maybe we should just make it a notation for that?
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Maintainer
I was also about to suggest a relation to idempotency,
Not sure if that's worth it.
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mentioned in merge request !79 (merged)