Weak Lefschetz conjecture for balanced minimal cycle complexes

Let a=(a1,,am)Z>0m\bm{a}=(a_1,\ldots,a_m)\in\mathbb{Z}_{>0}^m with d=i=1mai3d=\sum_{i=1}^m a_i\geq 3 and a(d1,1),(1,d1)\bm{a}\neq(d-1,1),(1,d-1). An (d1)(d-1)-dimensional simplicial complex Δ\Delta is a\bm{a}-balanced if it has a map κ:V(Δ)[m]\kappa:V(\Delta)\to[m] such that Fκ1(i)ai|F\cap\kappa^{-1}(i)|\leq a_i for every face FF and every i[m]i\in[m]; such a map is an a\bm{a}-coloring. Its Stanley–Reisner ring is R[Δ]=R[xv:vV(Δ)]/IΔ\mathbb{R}[\Delta]=\mathbb{R}[x_v:v\in V(\Delta)]/I_\Delta, with the Nm\mathbb{N}^m-grading determined by degxv=eκ(v)\deg x_v=\bm{e}_{\kappa(v)}. An a\bm{a}-colored system of parameters is a system of parameters Θ=(θ1,,θd)\Theta=(\theta_1,\ldots,\theta_d) with exactly aia_i parameters of degree ei\bm{e}_i. Let Δ\Delta be an a\bm{a}-balanced minimal (d1)(d-1)-cycle complex. Weak Lefschetz conjecture. There is an a\bm{a}-colored system of parameters Θ=(θ1,,θd)\Theta=(\theta_1,\ldots,\theta_d) for R[Δ]\mathbb{R}[\Delta] and a linear form ωR[Δ]1\omega\in\mathbb{R}[\Delta]_1 such that

(×ω):(R[Δ]/ΘR[Δ])1(R[Δ]/ΘR[Δ])2(\times\omega):(\mathbb{R}[\Delta]/\Theta\mathbb{R}[\Delta])_1\longrightarrow(\mathbb{R}[\Delta]/\Theta\mathbb{R}[\Delta])_2

is injective. This conjecture extends the result of Cook et al. for balanced simplicial 22-spheres to balanced minimal cycle complexes, with the exceptional vectors explicitly excluded; its resolution is connected to finding infinitesimally rigid non-generic realizations of these complexes.

Sources & referencesView supporting material

Primary source

Ryoshun Oba, “Rigidity of Balanced Minimal Cycle Complexes”, arXiv:2310.05005 (2023).

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.