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Stream: learning: questions

Topic: extremely nice monoidal closed categories


view this post on Zulip Chad Nester (Feb 17 2021 at 14:03):

Is there a name for (symmetric, strict) monoidal closed categories in which [I,A]=A[I,A] = A?

Have these been considered in the literature?

view this post on Zulip Chad Nester (Feb 17 2021 at 14:27):

I'm dabbling in programming language syntax, and in that context this says something like "everything is constructible", in the sense that AA consists of precisely the constant functions [I,A][I,A], and nothing else!

view this post on Zulip Dan Marsden (Feb 17 2021 at 14:42):

Isn't this always the case (up to iso) via a simple Yoneda argument in any monoidal closed category?

view this post on Zulip Cole Comfort (Feb 17 2021 at 14:43):

I take it that the question is asking when this holds on the nose

view this post on Zulip Dan Marsden (Feb 17 2021 at 14:45):

I'd think of that as extremely naughty rather than extremely nice :)

view this post on Zulip Cole Comfort (Feb 17 2021 at 14:48):

We ought to rename evil to naughty

view this post on Zulip Chad Nester (Feb 17 2021 at 15:14):

The question is indeed about when it holds on the nose!

view this post on Zulip Cole Comfort (Feb 17 2021 at 15:15):

I think you should call them monoidal naughty-closed categories

view this post on Zulip Mike Shulman (Feb 17 2021 at 15:24):

A more traditional name would be something like "(strictly) normal-closed" categories, since "normal" is often used when coherence involving units holds on the nose.

view this post on Zulip Mike Shulman (Feb 17 2021 at 15:25):

Unless I'm confused, you can make any closed monoidal category satisfy this equation by simply redefining the internal-hom functor. (At least, as long as you assume excluded middle, or the property of "being equal to II" is decidable.)

view this post on Zulip Chad Nester (Feb 18 2021 at 10:36):

That seems like it is probably true!

view this post on Zulip Chad Nester (Feb 18 2021 at 10:36):

Thanks for your answer :)