Circumscribed Caps Bound the Isosceles Count
ProvedProblem97.CGN8_circumscribed_iCount_upper_boundcircumscribed-capconvex-geometrycounting-bounderdos-97-96-countingisosceles-countlean-formalization
For a nonempty noncollinear convex-independent finite planar set with at least three MEC-boundary points, the total isosceles count satisfies iCount A ≤ ((11 · |A|² − 18 · |A|) / 12) over ℝ.
Preamble
/- Generated theorem stub from Erdos9796Proof.P97.CGN.CGN8 by Stage 2 proof cut; source SHA-256 e0d08238ab808e6b673b9006abffb488ad895fb6cf431ea389289a83884af65d -/ import Definitions.Def_Erdos9796Counting_Adapter import Definitions.Def_Erdos9796Counting_Foundation import Definitions.Def_Erdos9796Counting_IsoscelesCount import Definitions.Def_Erdos9796Counting_MEC_Basic import Mathlib.Algebra.BigOperators.Group.Finset.Basic open Problem97 /-! # CGN8: circumscribed cap upper bound This module is the circumscribed-branch counting closure from the counterexample-card-ge-nine prose. It combines the three-cap decomposition, the CGN4g support-cap packaging, the CGN6/CGN7 cap-local saving, the intra-cap disjointness lemma, and the cap-size Cauchy-Schwarz bound to produce the final circumscribed upper bound on `iCount`. -/ open scoped EuclideanGeometry open scoped InnerProductSpace open scoped BigOperators open Finset set_option maxHeartbeats 600000 in -- CGN8 packages three cap extractions, three cap-local savings, and the final -- finset/cardinality arithmetic in one theorem; elaboration needs a higher cap.
Formal statement
theorem Problem97.CGN8_circumscribed_iCount_upper_bound
{A : Finset ℝ²}
(hne : A.Nonempty)
(hnoncol : ¬ Collinear ℝ (A : Set ℝ²))
(hconv : ConvexIndep A)
(hbd : 3 <= (A.filter (fun p =>
dist p (Problem97.MEC.mec A hne).center =
(Problem97.MEC.mec A hne).radius)).card) :
(iCount A : ℝ) <= ((11 : ℝ) * A.card ^ 2 - 18 * A.card) / 12 := by sorrySource