Expected Syzygy Conjecture for chopped ideals of general points

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Let SS be the homogeneous coordinate ring of Pn\mathbb{P}^n, let ZZ be a general set of rr points, and let I(Z)I(Z) be its vanishing ideal. For an integer dd that is the smallest value such that hS(d)≥rh_S(d)\geq r, write I⟨d⟩=⟨I(Z)d⟩SI_{\langle d\rangle}=\langle I(Z)_d\rangle_S and let e0>0e_0>0 be the smallest integer such that the sum below is at least hS(d+e0)−rh_S(d+e_0)-r. Expected Syzygy Conjecture. For every e≥0e\geq 0,

hI⟨d⟩(d+e)={∑k≥1(−1)k+1hS(d+e−kd)(hS(d)−rk)e<e0,hS(d+e)−re≥e0.h_{I_{\langle d\rangle}}(d+e)=\begin{cases}\displaystyle\sum_{k\geq 1}(-1)^{k+1}h_S(d+e-kd)\binom{h_S(d)-r}{k}&e<e_0,\\ h_S(d+e)-r&e\geq e_0. \end{cases}

The conjecture expresses the expectation that, generically, the degree-dd equations of a set of points are as independent as possible, equivalently that their syzygies are generated by Koszul syzygies as long as the containment I⟨d⟩⊆I(Z)I_{\langle d\rangle}\subseteq I(Z) permits. The paper proves it in several infinite families and many computationally verified low-dimensional cases, but it is not established in general.

References

Primary source

Fulvio Gesmundo, Leonie Kayser and Simon Telen, “Hilbert Functions of Chopped Ideals”, arXiv:2307.02560 (2024).

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