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LeanPool.BrillNoetherGraphs.Bananas.Jacobian.BananaJacobianReducedUniqueness

Uniqueness of the paper's reduced banana coordinates #

This is the uniqueness layer in Proposition 2.14. Two preferred position vectors differing by the displayed lattice first give linearly equivalent left-reduced divisors, hence equal divisors by uniqueness of q-reduction.

The q-reduced core of uniqueness: displayed-equivalent paper representatives have exactly the same position-coordinate divisor.

Equality of position-coordinate divisors remembers the semibreak chip on each individual strand, despite the common endpoint aliases.

theorem Bananas.positionCoordinate_eq_of_interior_of_divisor_eq {g : ℕ} (B : Banana g) (p q : (alpha : Fin (g + 1)) → Utilities.Certificate.SubdivisionGraph.Spec.PathPosition B alpha) (hDiv : bananaPositionCoordinateDivisor B p = bananaPositionCoordinateDivisor B q) (alpha : Fin (g + 1)) (hpInterior : IsPaperInteriorCoordinate B p alpha) :
p alpha = q alpha

An interior coordinate is recovered strand-by-strand from the associated position-coordinate divisor.

The apparent endpoint aliases do not create a second preferred representative: the ordering clause makes the endpoint assignment unique.