The graph-regime fibres of the (eta,nu) region in exact-blest-regions.tex.
theorem
Papers.Rockel2026ExactBlest.nu_le_familyA
(C : ProbabilityTheory.Copula 2)
(w : ↑unitInterval)
(hw : ↑w ≤ 1 / 2)
(he : eta C = eta (familyA w))
:
theorem
Papers.Rockel2026ExactBlest.graph_fibre
(w : ↑unitInterval)
(hw : ↑w ≤ 1 / 2)
(n : ℝ)
:
(∃ (C : ProbabilityTheory.Copula 2), eta C = eta (familyA w) ∧ Rockel2026XiBlest.blestNu C = n) ↔ n ∈ Set.Icc (2 * eta (familyA w) - Rockel2026XiBlest.blestNu (familyA w)) (Rockel2026XiBlest.blestNu (familyA w))
Exact fibres for the graph regime, in the paper's parameter w; uniqueness is not asserted.
theorem
Papers.Rockel2026ExactBlest.rho_eta_lower_attained :
∃ (C : ProbabilityTheory.Copula 2), C.spearmanRho - eta C = -27 / 128