Dice Question Streamline Icon: https://streamlinehq.com

Waldschmidt constants of matroid configurations with non-uniform specialization degrees

Compute explicitly the Waldschmidt constant ẑα(φ_*(I_{Δ(M)})) for matroid configurations when the specializing forms f_1,…,f_n have arbitrary (not all equal) degrees, i.e., develop effective methods to evaluate min_{1≤r≤|E|−rk(M)} (Σ_{i∈U} deg f_i)/r over circuits U of the elongations M^{(r)}.

Information Square Streamline Icon: https://streamlinehq.com

Background

When all f_i have the same degree δ, the paper proves ẑα(φ*(IΔ))=δ·ẑα(I_Δ). For non-uniform degrees, Corollary 7.3 expresses ẑα(φ*(IΔ)) as a minimum of weighted circuit sums across elongations, but no general computational method is provided.

An explicit, generally applicable computation or simplification in the non-uniform degree case remains open.

References

Question. Can we compute (explicitly) the Waldschmidt constant of \phi_*(I_{\Delta(M)}) when the polynomials f_1,\ldots, f_n are not of the same degree? By Corollary~\ref{cor: matroid config invariants}, this amounts to weighting the elements of the ground set of M by the degrees of f_1,\ldots,f_n and computing the minimum of weighted circuit sums for the elongations M{(r)}, 1\le r\le n-k, normalized by r.

Generalized Hamming weights and symbolic powers of Stanley-Reisner ideals of matroids (2406.13658 - DiPasquale et al., 19 Jun 2024) in Section 8, Concluding remarks and questions