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Project-declaredLean 4.31.0 · mathlib@fabf563a

Prop4d1₁

HarderNarasimhan.impl.prop4d1₁

Plain-language statement

prop4d1₁ is the core statement behind Proposition 4.1: under the two hypotheses h₁ (a weak “eventual improvement” along strict chains) and h₂ (a weak slope-like alternative towards the top), the best-response value μAstar μ coincides with the global infimum μmin μ TotIntvl.

Exact Lean statement

lemma prop4d1₁ (ℒ : Type*) [Nontrivial ℒ] [PartialOrder ℒ] [BoundedOrder ℒ]
(S : Type*) [CompleteLattice S]
(μ : {p :ℒ × ℒ // p.1 < p.2} → S)
(h₁ : ∀ x : ℕ → ℒ, (smf : StrictMono x) →
  ∃ N : ℕ, μ ⟨(x N, x (N+1)), smf <| Nat.lt_add_one N⟩ ≤
    μ ⟨(x N,⊤), lt_of_lt_of_le (smf <| Nat.lt_add_one N) le_top⟩)
(h₂ : ∀ z : {p :ℒ × ℒ // p.1 < p.2}, (hz :z.val.2 < ⊤) →
  μ z ≤ μ ⟨(z.val.1,⊤),lt_trans z.prop hz⟩ ∨ μ ⟨(z.val.2,⊤),hz⟩ ≤
  μ ⟨(z.val.1,⊤),lt_trans z.prop hz⟩) :
μAstar μ = μmin μ TotIntvl

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma prop4d1₁ (ℒ : Type*) [Nontrivial ℒ] [PartialOrder ℒ] [BoundedOrder ℒ](S : Type*) [CompleteLattice S](μ : {p :ℒ × ℒ // p.1 < p.2}  S)(h₁ :  x :   ℒ, (smf : StrictMono x)    N : , μ (x N, x (N+1)), smf <| Nat.lt_add_one N     μ (x N,⊤), lt_of_lt_of_le (smf <| Nat.lt_add_one N) le_top)(h₂ :  z : {p :ℒ × ℒ // p.1 < p.2}, (hz :z.val.2 < ⊤)   μ z  μ (z.val.1,⊤),lt_trans z.prop hz  μ (z.val.2,⊤),hz   μ (z.val.1,⊤),lt_trans z.prop hz) :μAstar μ = μmin μ TotIntvl := by  rw [ prop4d1_helper]  have :  yA : ℒ, (hyA : yA < ⊤)   xA : ℒ, xA < ( xB : ℒ, (hAB : xA < xB)     μ (xA,xB), hAB  μ (yA,⊤), hyA) := by    by_contra!    replace : {YA : ℒ |  (h : YA < ⊤),  xA < ⊤,  xB,  (hAB : xA < xB), ¬μ (xA, xB), hAB       μ (YA, ⊤), h}.Nonempty := this    have hsmf : StrictMono (fun n  prop4d1₁_seq μ h₁ h₂ this n) :=      strictMono_nat_of_lt_succ <| fun n  ((prop4d1₁_seq μ h₁ h₂ this n).prop.out.choose_spec      (prop4d1₁_seq μ h₁ h₂ this n) (prop4d1₁_seq μ h₁ h₂ this n).prop.out.choose      ).choose_spec.choose    have hfinal :  n : , ¬ μ ((prop4d1₁_seq μ h₁ h₂ this n),(prop4d1₁_seq μ h₁ h₂ this (n+1))),      hsmf (Nat.lt_add_one n)  μ ((prop4d1₁_seq μ h₁ h₂ this n),⊤),lt_of_lt_of_le      (hsmf (Nat.lt_add_one n)) le_top := fun n  ((prop4d1₁_seq μ h₁ h₂ this n      ).prop.out.choose_spec (prop4d1₁_seq μ h₁ h₂ this n) (prop4d1₁_seq μ h₁ h₂ this n      ).prop.out.choose).choose_spec.choose_spec    rcases h₁ (fun n  prop4d1₁_seq μ h₁ h₂ this n) hsmf with N,hN    exact (hfinal N) hN  refine le_antisymm ?_ ?_  · apply le_sInf    rintro y yA, hyA, h    rcases this yA hyA with xA, hxA, h'    replace : μmax μ (xA,⊤),hxA  {μmax μ (a , ⊤),(lt_of_le_of_ne ha.1.2 ha.2) |      (a : ℒ) (ha : InIntvl TotIntvl a  a  ⊤)} := by      refine Set.mem_setOf.mpr ?_      use xA, in_TotIntvl xA,ne_top_of_lt hxA    refine h.symm ▸ (sInf_le_of_le this <| sSup_le ?_)    rintro _ xB,hxB,hxB'⟩⟩    exact hxB' ▸ h' xB (lt_of_le_of_ne hxB.1.1 hxB.2)  · apply le_sInf    rintro t x, hx, h    replace : μ (x,⊤),lt_top_iff_ne_top.2 hx.2       {x |  x_1,  (hx : x_1 < ⊤), μ (x_1, ⊤), hx = x} := by      refine Set.mem_setOf.mpr ?_      use x, lt_top_iff_ne_top.2 hx.2    refine h.symm ▸ (sInf_le_of_le this <| Set.mem_setOf.mpr <| le_sSup ?_)    use ⊤, ⟨⟨le_top,le_top,hx.2
Project
Harder-Narasimhan
License
Apache-2.0
Commit
20220e90b72c
Source
HarderNarasimhan/FirstMoverAdvantage/Impl.lean:91-136

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Related declarations

Project-declaredLean 4.31.0

Associated Primes ker mk Linear Map eq

HarderNarasimhan.CommutativeAlgebra.associatedPrimes_ker_mkLinearMap_eq

Project documentation

Associated primes of the kernel of the localization map. This identifies the associated primes of ker (LocalizedModule.mkLinearMap S M) : Submodule R M with the associated primes of M that do meet the multiplicative set S. Equivalently, these are the associated primes of M after removing those disjoint from S. This lemma is used as the “kernel...

algebraic geometryvector bundlescategory theory

Source project: Harder-Narasimhan

Person-level attribution pending.

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Project-declaredLean 4.31.0

Associated Primes ker mk Linear Map subset

HarderNarasimhan.CommutativeAlgebra.associatedPrimes_ker_mkLinearMap_subset

Plain-language statement

One-sided inclusion for associated primes of the kernel of the localization map. If p ∈ associatedPrimes R (ker (mkLinearMap S M)), then p is an associated prime of M and p is not disjoint from the multiplicative set S. This is one direction of associatedPrimes_ker_mkLinearMap_eq.

algebraic geometryvector bundlescategory theory

Source project: Harder-Narasimhan

Person-level attribution pending.

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Project-declaredLean 4.31.0

Associated Primes localized Module subset disjoint

HarderNarasimhan.CommutativeAlgebra.associatedPrimes_localizedModule_subset_disjoint

Plain-language statement

Associated primes of a localized module are disjoint from the multiplicative set. More precisely, if p ∈ associatedPrimes R (LocalizedModule S M), then p.carrier ∩ S = ∅. This is a standard fact in commutative algebra: an element of S becomes a unit after localization, so no associated prime of the localized module can contain an element of S.

algebraic geometryvector bundlescategory theory

Source project: Harder-Narasimhan

Person-level attribution pending.

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