Positive Laurent formula conjecture for the stacked twist map

Let VV and WW be matrices whose stacked matrix is U:=stack(V,W)Mat(k+,n)U:=\operatorname{stack}(V,W)\in\operatorname{Mat}^{\circ}(k+\ell,n), and let the stacked twist map satisfy θ(V,W)=(W~,V~)\theta(V,W)=(\widetilde W,\widetilde V). Write U~:=τ(U)=stack(W~,V~)\widetilde U:=\tau(U)=\operatorname{stack}(\widetilde W,\widetilde V), Z:=WZ:=W^\perp, and Z~:=W~\widetilde Z:=\widetilde W^\perp. Positive Laurent formula conjecture. There exist polynomials HH and HH' in the maximal minors of VV and ZZ, with nonnegative integer coefficients, such that for every I([n]+m)I\in{[n]\choose \ell+m} and I([n])I\in{[n]\choose \ell} respectively,

ΔI(Z~)=H±jIΔ[j,j+k)(U),\Delta_I(\widetilde Z)=\frac{H}{\pm\prod_{j\in I}\Delta_{[j-\ell,j+k)}(U)},

and

ΔI(V~)=H±jIΔ[j,j+k)(U).\Delta_I(\widetilde V)=\frac{H'}{\pm\prod_{j\in I}\Delta_{[j-\ell,j+k)}(U)}.

This predicts positivity and Laurent-type expressions for twisted Plücker coordinates; the source gives no resolution.

Sources & referencesView supporting material

Primary source

Pavel Galashin and Thomas Lam, “Parity duality for the amplituhedron”, arXiv:1805.00600 (2018).

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