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 TotIntvlFormal artifact
Lean source
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 := 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 : 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
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...
Source project: Harder-Narasimhan
Person-level attribution pending.
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.
Source project: Harder-Narasimhan
Person-level attribution pending.
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.
Source project: Harder-Narasimhan
Person-level attribution pending.