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[Merged by Bors] - feat(order/filter): change definition of inf #8657

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@PatrickMassot PatrickMassot commented Aug 13, 2021

The current definition of filter.inf came directly from the Galois insertion: u ∈ f ⊓ g if it contains s ∩ t for some s ∈ f and t ∈ g, but the new one is tidier: u ∈ f ⊓ g if u = s ∩ t for some s ∈ f and t ∈ g. This gives a stronger assertion to work with when assuming a set belongs to a filter inf. On the other hand it makes it harder to prove such a statement so we keep the old version as a lemma filter.mem_inf_of_inter : ∀ {f g : filter α} {s t u : set α}, s ∈ f → t ∈ g → s ∩ t ⊆ u → u ∈ f ⊓ g.

Also renames lots of lemmas to remove the word "sets" that was a remnant of the very early days.

In passing I also changed the simp lemma filter.mem_map from t ∈ map m f ↔ {x | m x ∈ t} ∈ f to
t ∈ map m f ↔ m ⁻¹' t ∈ f which seemed more normal form to me. But this led to a lot of breakage, so I also kept the old version as mem_map'.


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@PatrickMassot PatrickMassot added the awaiting-review The author would like community review of the PR label Aug 13, 2021
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LGTM. I'll leave some time for others to have a look if they want, but still I think we should merge this pretty quickly to avoid conflicts.
Let's say you can merge this by tomorrow (14/08/2021) noon if nobody has further comments by then.
bors d+

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bors bot commented Aug 13, 2021

✌️ PatrickMassot can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

@github-actions github-actions bot added delegated The PR author may merge after reviewing final suggestions. and removed awaiting-review The author would like community review of the PR labels Aug 13, 2021
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urkud commented Aug 13, 2021

I golfed a few proofs. LGTM. Thanks!
bors d+

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bors bot commented Aug 13, 2021

✌️ PatrickMassot can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

@github-actions github-actions bot added the merge-conflict Please `git merge origin/master` then a bot will remove this label. label Aug 13, 2021
PatrickMassot and others added 6 commits August 13, 2021 23:39
also renames lots of lemmas to remove the word "sets" that was a remnant
of the very early days.
Co-authored-by: sgouezel <sebastien.gouezel@univ-rennes1.fr>
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bors merge

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👎 Rejected by label

@github-actions github-actions bot added ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.) and removed merge-conflict Please `git merge origin/master` then a bot will remove this label. labels Aug 13, 2021
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bors merge

bors bot pushed a commit that referenced this pull request Aug 13, 2021
The current definition of `filter.inf` came directly from the Galois insertion: `u ∈ f ⊓ g` if it contains `s ∩ t` for some `s ∈ f` and `t ∈ g`, but the new one is tidier: `u ∈ f ⊓ g` if `u = s ∩ t` for some `s ∈ f` and `t ∈ g`. This gives a stronger assertion to work with when assuming a set belongs to a filter inf. On the other hand it makes it harder to prove such a statement so we keep the old version as a lemma `filter.mem_inf_of_inter :  ∀ {f g : filter α} {s t u : set α}, s ∈ f → t ∈ g → s ∩ t ⊆ u → u ∈ f ⊓ g`.

Also renames lots of lemmas to remove the word "sets" that was a remnant of the very early days.

In passing I also changed the simp lemma `filter.mem_map` from  `t ∈ map m f ↔ {x | m x ∈ t} ∈ f` to 
`t ∈ map m f ↔ m ⁻¹' t ∈ f` which seemed more normal form to me. But this led to a lot of breakage, so I also kept the old version as `mem_map'`.



Co-authored-by: Yury G. Kudryashov <urkud@urkud.name>
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bors bot commented Aug 13, 2021

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(order/filter): change definition of inf [Merged by Bors] - feat(order/filter): change definition of inf Aug 13, 2021
@bors bors bot closed this Aug 13, 2021
@bors bors bot deleted the filter_stuff branch August 13, 2021 23:32
PatrickMassot added a commit that referenced this pull request Aug 15, 2021
Also finishes the filter inf work from #8657 proving stronger lemmas for
filter.infi
bors bot pushed a commit that referenced this pull request Aug 23, 2021
Also finishes the filter inf work from #8657 proving stronger lemmas for
filter.infi



Co-authored-by: Johan Commelin <johan@commelin.net>
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3 participants