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Jul 21, 2022 at 17:57 vote accept Max New
Jul 21, 2022 at 6:53 history edited Jonathan Sterling CC BY-SA 4.0
clean up
Jul 21, 2022 at 6:48 comment added Jonathan Sterling @MaxNew added the example
Jul 21, 2022 at 6:48 history edited Jonathan Sterling CC BY-SA 4.0
add explicit counterexample
Jul 20, 2022 at 22:38 comment added Max New If you want to add in the explicit counterexample $$\forall k. \exists n. (\triangleright^k)^n \bot$$ we discussed on zulip I'll go ahead an accept the answer
Jul 18, 2022 at 13:32 comment added Max New "Axiom of clockable choice"?
Jul 18, 2022 at 12:46 history edited Jonathan Sterling CC BY-SA 4.0
My comments are no longer conjectural.
Jul 18, 2022 at 12:19 comment added Jonathan Sterling Updated my answer accordingly.
Jul 18, 2022 at 12:19 history edited Jonathan Sterling CC BY-SA 4.0
typo
Jul 18, 2022 at 12:09 comment added Jonathan Sterling That's right! Btw, I think that if A and \phi are both clock irrelevant, then it might in fact be possible to commute the existential under certain circumstances. Let me compute a bit more, and I'll update my answer.
Jul 18, 2022 at 12:05 comment added Max New Oh I see, if you interpret the clock quantification as just a Pi type this is essentially a form of axiom of choice, and commuting with Sigma types is the usual “incorrect” rendering of AC.
Jul 18, 2022 at 11:49 comment added Jonathan Sterling In fact, in MLTT for any type $K$ and families $k:K \vdash Ak$ and $k:K, x:Ak \vdash Bkx$ the sigma type commutation law that you described holds.
Jul 18, 2022 at 11:31 comment added Max New Just to confirm: in these topos models the clock quantification does commute with Sigma types?
Jul 18, 2022 at 10:41 history answered Jonathan Sterling CC BY-SA 4.0