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by hackandthink·3y ago·view on hn ↗

Some people think:

If you can't compute it, it does not exist.

If you can't compute it, I don't care.

Computing and real numbers are a confusing subject.

Edit:

https://ncatlab.org/nlab/show/computable+physics

There are nice discussions an Andrej Bauer's blog: https://math.andrej.com/.

Can't find them right now.

"type II computability" is the concept.

Look at the table in:

https://ncatlab.org/nlab/show/Type+Two+Theory+of+Effectivity

1 comments

Quip: Can the tuna salad sandwich I am eating for lunch be computed? Does it exist? Should I care?

Not a sandwich but an equilibrium.

What is it good for if there's no mechanism to reach it?

"What they’ve found is that some games have Nash equilibria that are impossible for a computer to determine and even more equilibria are computable only if one of the largest open problems in computer science, P = NP, is solved."

https://blogs.cornell.edu/info2040/2015/09/21/the-computabil...

I am not even sure if one can say that tuna itself "exists," in this context.

I think first you would have to define what it means to be computed in this context.