Integral-group and Ehrhart characterization conjecture for uniform clutters
Let be a uniform clutter with edge incidence vectors , and suppose its packing property holds. Define
as the matrix whose columns are the augmented vectors, let be the rank of , let be the corresponding determinantal divisor, and set
Here is the integral closure of the homogeneous ring , and is the Ehrhart ring of . Integral-group and Ehrhart characterization conjecture. If is a uniform clutter with the packing property, then all of the following equivalent conditions hold: (a) is a free group; (b) ; (c) diagonalizes over to an identity matrix; and (d) . The source presents this as a consequence suggested by the preceding conjecture, but gives no resolution status.
References
Primary source
Luis A. Dupont and Rafael H. Villarreal, “Algebraic and combinatorial properties of ideals and algebras of uniform clutters of TDI systems”, arXiv:0801.1478 (2009).
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