Documentation

Copula.Rank.Region.RhoTau.SparseVariations

← Copula mathematical handbook
@[simp]
theorem ProbabilityTheory.Copula.RankRegion.RhoTau.sum_spike {ι : Type u_1} [Fintype ι] [DecidableEq ι] (i : ι) :
∑ j : ι, spike i j = 1
@[simp]
theorem ProbabilityTheory.Copula.RankRegion.RhoTau.SignData.a_three {ι : Type u_1} [Fintype ι] [DecidableEq ι] (S : SignData ι) (p q r : ι) (x y z : ℝ) :
S.a (x • spike p + y • spike q + z • spike r) = S.inversion p q * x * y + S.inversion p r * x * z + S.inversion q r * y * z
theorem ProbabilityTheory.Copula.RankRegion.RhoTau.SignData.b_three {ι : Type u_1} [Fintype ι] [DecidableEq ι] (S : SignData ι) (p q r : ι) (x y z : ℝ) :
S.b (x • spike p + y • spike q + z • spike r) = S.triple p q r * x * y * z
theorem ProbabilityTheory.Copula.RankRegion.RhoTau.SignData.second_three {ι : Type u_1} [Fintype ι] [DecidableEq ι] (S : SignData ι) (p q r : ι) (x y z : ℝ) (u : ι → ℝ) :
3 * S.trilinear (x • spike p + y • spike q + z • spike r) (x • spike p + y • spike q + z • spike r) u = S.pairCoefficient u p q * x * y + S.pairCoefficient u p r * x * z + S.pairCoefficient u q r * y * z
theorem ProbabilityTheory.Copula.RankRegion.RhoTau.SignData.increasing_triple_reduction {ι : Type u_1} [Fintype ι] [DecidableEq ι] (S : SignData ι) (u : ι → ℝ) (hu : ∀ (i : ι), 0 < u i) (p q r : ι) (hpq : p ≠ q) (hpr : p ≠ r) (hqr : q ≠ r) (hpq' : S.inversion p q = 0) (hpr' : S.inversion p r = 0) (hqr' : S.inversion q r = 0) (ht : S.triple p q r = 0) :
∃ (v : ι → ℝ), (∀ (i : ι), 0 ≤ v i) ∧ ∑ i : ι, v i = ∑ i : ι, u i ∧ (∃ (i : ι), v i = 0) ∧ S.a v = S.a u ∧ S.b v ≤ S.b u

The increasing-triple direction preserves the quadratic and decreases the cubic at a simplex boundary, as in Lemmas 4.6(i) and 4.7.