The explicit endpoint transmission block #
The endpoint pencil determines a decreasing block in the transmission permutation. This is the algebraic input to the endpoint inversion bound.
theorem
Bananas.exists_endpoint_transmission_block
{g k : ℕ}
(B : Banana g)
(hsub : AllSubmodular (mark (Utilities.Certificate.SubdivisionGraph.Spec.graph B) (leftEndpoint B) (rightEndpoint B)))
(hk : TorsionWitness (mark (Utilities.Certificate.SubdivisionGraph.Spec.graph B) (leftEndpoint B) (rightEndpoint B)) k)
:
∃ (τ : ℤ → ℤ),
IsTransmissionPermutation
(mark (Utilities.Certificate.SubdivisionGraph.Spec.graph B) (leftEndpoint B) (rightEndpoint B))
(g • oneChip (rightEndpoint B)) τ ∧ IsKAffine k τ ∧ ∀ b ≤ g, τ ↑b = ↑(g - b)
theorem
Bananas.endpoint_affine_period_gt_genus
{g k : ℕ}
{τ : ℤ → ℤ}
(hk : 0 < k)
(hAffine : IsKAffine k τ)
(hBlock : ∀ b ≤ g, τ ↑b = ↑(g - b))
:
The decreasing endpoint block forces every affine period to be larger
than the genus. In particular its choose (g+1) 2 ordinary inversions lie
in distinct period classes.