Explicit real support fans for the handwritten geometric point set. The polynomial decompositions are proved by ring; their signs by positivity. Each cone carries one fixed triple on both endpoints. No Boolean checker is used.

noncomputable def ConwaySoifer.Simplified.acrossLargeSidePoint : Fin 4 → Point

The four mandatory side-owner points in the large-parameter Across obstruction.

Equations

• ConwaySoifer.Simplified.acrossLargeSidePoint = ![(-3 / 25, 1), (0, 9 / 10), (1, 1 / 2), (0, 1)]

theorem ConwaySoifer.Simplified.acrossLargeSide_obstruction {Q : EquilateralTriangle} (hq : 0 < Q.side) (hpts : ∀ (i : Fin 4), acrossLargeSidePoint i ∈ Q.carrier) : 1 ≤ Q.side