Consecutive Minor-Cap Chain Triples Are Nonacute
ProvedProblem97.CGN.CGN6b_nonacute_of_minorCapChainCoordscap-witnessconvex-geometryerdos-97-96-countinglean-formalizationminor-capnonacute-triangle
For a normalized minor-cap chain coordinate model, any three increasing indices form a nonacute angle at the middle point: the inner product of the two vectors from the middle point to the outer points is nonpositive.
Preamble
/- Generated theorem stub from Erdos9796Proof.P97.CGN.CGN6 by Stage 2 proof cut; source SHA-256 87eeea2860c10b6c484c3d7aec9f295605a553c9956e5cc04bbc649402bc9c30 -/ import Definitions.Def_Erdos9796Counting_Adapter import Definitions.Def_Erdos9796Counting_CGN_CGN6 import Definitions.Def_Erdos9796Counting_Foundation import Mathlib.Analysis.Convex.Hull import Mathlib.Analysis.InnerProductSpace.Basic import Mathlib.Analysis.InnerProductSpace.Orthonormal import Mathlib.Analysis.InnerProductSpace.TwoDim import Mathlib.Geometry.Euclidean.PerpBisector import Mathlib.Order.Interval.Finset.Fin open Problem97 Problem97.CGN /-! # CGN6: normalized minor-cap chain model This file starts the CGN6 layer named in the updated counterexample-card-ge-nine prose. It records the normalized minor-cap chain data the prose uses for the CGN6b slope-product argument: ordered coordinates, endpoint normalization, the unit-disk bound, and the adjacent-slope bookkeeping. The actual geometric construction of this model from a concrete MEC cap packet is still separate. This file only provides the data interface the subsequent CGN6b / CGN6c proofs will consume. -/ open scoped EuclideanGeometry open scoped InnerProductSpace open scoped BigOperators /- ### CGN6norm scaffold The prose normalization theorem uses an explicit coordinate frame centered at the chord midpoint and aligned with the chord / inward normal directions. The full packet-to-frame bridge is still separate; this helper records the coordinate map in the exact algebraic form used by the prose. -/ -- The normalization proof is large enough to need a higher elaboration budget.
Formal statement
theorem Problem97.CGN.CGN6b_nonacute_of_minorCapChainCoords {m : ℕ} (L : MinorCapChainCoords m) :
∀ {i j k : Fin m}, i < j → j < k →
⟪point L.X L.Y i - point L.X L.Y j, point L.X L.Y k - point L.X L.Y j⟫_ℝ ≤ 0 := by sorrySource