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Structure presheaf #699

Merged
merged 24 commits into from
Jan 25, 2022
Merged

Structure presheaf #699

merged 24 commits into from
Jan 25, 2022

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mzeuner
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@mzeuner mzeuner commented Jan 21, 2022

This PP introduces the basic opens of the Zariski lattice and constructs the structure presheaf on them.

@mortberg
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I'll restart the CI for this PR now just to check that things still work after merging that revert


-- The structure presheaf on BO
BOCat : Category (ℓ-suc ℓ) (ℓ-suc ℓ)
BOCat = ΣPropCat (DistLatticeCategory ZariskiLattice) BasicOpens
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One problem that maybe should be discussed before merging:
Using general machinery to define the structure sheaf through the universal property of localization,
we view the basic opens to as a category in the above way. This unfolds to them being a JoinSemilatticeCategory.

In the file Cubical.Categories.DistLatticeSheaf, the basic opens are viewed as a MeetSemilatticeCategory.

The two definitions come from the two ways of defining the order relation on a distributive lattice
(x≤y as y=x\/y vs x=x/\y) and they're thus equivalent but not definitionally equal.

I just thought maybe want make things uniform in one way or the other...

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Good catch! It's probably easier to change the DistLatticeSheaf? I can try to remember to do it when working on that file




-- the Algebra version of uaCompEquiv
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Are these lemmas really useful?

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Looks good to me!

@mortberg mortberg merged commit 6371279 into agda:master Jan 25, 2022
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2 participants