BV-alpha positivity conjecture for regular permutohedra

From papers

Let PP be a polytope. In McMullen's formula, write the local contribution associated with a face FF as α(F,P)\alpha(F,P), and use the Berline–Vergne construction for these local terms, called the BV-α\alpha-valuation. The polytope PP is BV-α\alpha-positive when all BV-α\alpha values associated with PP are positive.

BV-alpha positivity conjecture. Every regular permutohedron is BV-α\alpha-positive.

The conjecture is based on computations in small dimensions, where the symmetry of regular permutohedra makes the recursive BV-α\alpha-valuation tractable. A general proof is not supplied and the conjecture remains open.

Progress summary

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Equivalent formulations 1

Other statements of this same problem, merged from separate entries. Each is equivalent to the statement above — proving any one settles them all.

  1. BV-α\alpha-positivity conjecture for regular permutohedra

    Let Πd\Pi_d denote the regular permutohedron, the usual permutohedron associated with (1,2,,d+1)(1,2,\dots,d+1). The BV-α\alpha-valuation is the valuation used in the paper's McMullen-type formula, and a polytope is BV-α\alpha-positive when the corresponding coefficients in that formula are positive. BV-α\alpha-positivity conjecture. Every regular permutohedron Πd\Pi_d is BV-α\alpha-positive. This conjecture is a reduction of the Ehrhart positivity conjecture for integral generalized permutohedra, and the paper reports partial progress toward both statements.

    source: Fu Liu, “On positivity of Ehrhart polynomials”, arXiv:1711.09962 (2018).

Sources & referencesView supporting material

Primary source

Federico Castillo and Fu Liu, “Berline-Vergne valuation and generalized permutohedra”, arXiv:1509.07884 (2017).

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