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[Merged by Bors] - feat(order/sup_indep): Finite supremum independence #9867

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YaelDillies
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This defines supremum independence of indexed finsets.


Note, this is currently very redundant with set.pairwise_disjoint, both notions being equivalent in distributive lattices. The expectation is that we'll be able to talk about disjointness and sup (simultaneously!) in non distributive lattices sometimes soon.
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@YaelDillies YaelDillies added the WIP Work in progress label Oct 21, 2021
@YaelDillies YaelDillies added awaiting-review The author would like community review of the PR and removed WIP Work in progress labels Oct 24, 2021
src/order/sup_indep.lean Outdated Show resolved Hide resolved
Co-authored-by: Johan Commelin <johan@commelin.net>
@eric-wieser
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Can we add this lemma or a variant of it somewhere?

lemma sup_indep_iff {α} [complete_distrib_lattice α] (s : finset ι) (f : ι → α) :
  complete_lattice.independent (f ∘ (coe : s → ι)) ↔ sup_indep s f :=
begin
  rw complete_lattice.independent, rw sup_indep,
  refine subtype.forall.trans _,
  refine forall_congr _,
  intros a,
  refine forall_congr _,
  intros b,
  rw finset.sup_eq_supr,
  apply iff_of_eq,
  congr' 1,
  refine supr_subtype.trans _,
  congr' 1 with x,
  simp [supr_and],
  rw supr_comm,

end

bors bot pushed a commit that referenced this pull request Nov 4, 2021
…se_disjoint` (#9898)

This will allow to express the bind operation: you can't currently express that the pairwise disjoint union of pairwise disjoint sets pairwise disjoint. Here's the corresponding statement with `finset.sup_indep` (defined in #9867):
```lean
lemma sup_indep.sup {s : finset ι'} {g : ι' → finset ι} {f : ι → α}
  (hs : s.sup_indep (λ i, (g i).sup f)) (hg : ∀ i' ∈ s, (g i').sup_indep f) :
  (s.sup g).sup_indep f :=
```
You currently can't do `set.pairwise_disjoint s (λ i, ⋃ x ∈ g i, f x)`.



Co-authored-by: Eric Wieser <wieser.eric@gmail.com>
bors bot pushed a commit that referenced this pull request Nov 4, 2021
…se_disjoint` (#9898)

This will allow to express the bind operation: you can't currently express that the pairwise disjoint union of pairwise disjoint sets pairwise disjoint. Here's the corresponding statement with `finset.sup_indep` (defined in #9867):
```lean
lemma sup_indep.sup {s : finset ι'} {g : ι' → finset ι} {f : ι → α}
  (hs : s.sup_indep (λ i, (g i).sup f)) (hg : ∀ i' ∈ s, (g i').sup_indep f) :
  (s.sup g).sup_indep f :=
```
You currently can't do `set.pairwise_disjoint s (λ i, ⋃ x ∈ g i, f x)`.



Co-authored-by: Eric Wieser <wieser.eric@gmail.com>
src/order/sup_indep.lean Outdated Show resolved Hide resolved
ericrbg pushed a commit that referenced this pull request Nov 9, 2021
…se_disjoint` (#9898)

This will allow to express the bind operation: you can't currently express that the pairwise disjoint union of pairwise disjoint sets pairwise disjoint. Here's the corresponding statement with `finset.sup_indep` (defined in #9867):
```lean
lemma sup_indep.sup {s : finset ι'} {g : ι' → finset ι} {f : ι → α}
  (hs : s.sup_indep (λ i, (g i).sup f)) (hg : ∀ i' ∈ s, (g i').sup_indep f) :
  (s.sup g).sup_indep f :=
```
You currently can't do `set.pairwise_disjoint s (λ i, ⋃ x ∈ g i, f x)`.



Co-authored-by: Eric Wieser <wieser.eric@gmail.com>
@fpvandoorn
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LGTM

bors merge

@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 awaiting-review The author would like community review of the PR labels Nov 15, 2021
bors bot pushed a commit that referenced this pull request Nov 15, 2021
This defines supremum independence of indexed finsets.
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bors bot commented Nov 15, 2021

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(order/sup_indep): Finite supremum independence [Merged by Bors] - feat(order/sup_indep): Finite supremum independence Nov 15, 2021
@bors bors bot closed this Nov 15, 2021
@bors bors bot deleted the sup_indep branch November 15, 2021 12:42
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4 participants