Betti-number conjecture for lattice polygons and toric surfaces

About 10 years old · traced to

Let Δ⊆R2\Delta\subseteq\mathbb{R}^2 be a lattice polygon whose interior polygon Δ(1)\Delta^{(1)} is two-dimensional and contains g≥4g\geq 4 lattice points. Assume that Δ(1)≇Υ\Delta^{(1)}\not\cong\Upsilon. Denote the graded Betti table of XΔ(1)⊆Pg−1X_{\Delta^{(1)}}\subseteq\mathbb{P}^{g-1} by bℓb_\ell as in the source. The toric Betti-table conjecture. Then

min⁡{ℓ∣bg−ℓ≠0}={lw⁡(Δ(1))+1if Δ(1)≅(d−3)Σ for some d≥5,lw⁡(Δ(1))+1if Δ(1)≅2Υ,lw⁡(Δ(1))+2in all other cases.\min\{\ell\mid b_{g-\ell}\neq 0\}=\begin{cases} \operatorname{lw}(\Delta^{(1)})+1 & \text{if }\Delta^{(1)}\cong(d-3)\Sigma\text{ for some }d\geq 5,\\ \operatorname{lw}(\Delta^{(1)})+1 & \text{if }\Delta^{(1)}\cong2\Upsilon,\\ \operatorname{lw}(\Delta^{(1)})+2 & \text{in all other cases.} \end{cases}

The conjecture predicts the first relevant nonzero Betti number of the toric surface from the lattice width of its interior polygon, with two explicitly identified exceptional families. The supplied material gives no resolution status.

References

Primary source

Wouter Castryck, Filip Cools, Jeroen Demeyer and Alexander Lemmens, “Canonical syzygies of smooth curves on toric surfaces”, arXiv:1609.02360 (2019).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.