Lew's extremal characterization conjecture for simplicial complexes

About 2 years old · traced to

Let XX be a simplicial complex on vertex set VV of size nn, with h(X)=dh(X)=d. Write μk(X)\mu_k(X) for the parameter appearing in the equality below, and let Δm\Delta_m denote the complete simplicial complex on m+1m+1 vertices; Δd(d−1)\Delta_d^{(d-1)} is its (d−1)(d-1)-dimensional skeleton. The symbol ∗* denotes the join of simplicial complexes, and X≅YX\cong Y means that XX and YY are isomorphic simplicial complexes. Lew's conjecture. If

μk(X)=(d+1)(k+1)−dn\mu_k(X)=(d+1)(k+1)-dn

for some kk, then

X≅(Δd(d−1))∗(n−k−1)∗Δ(d+1)(k+1)−dn−1.X\cong \left(\Delta_d^{(d-1)}\right)^{*(n-k-1)}*\Delta_{(d+1)(k+1)-dn-1}.

In particular, dim⁡(X)=k\dim(X)=k. Lew proposed this as a characterization of the simplicial complexes attaining equality in the relevant spectral-gap lower bound; the supplied source does not state whether the conjecture has been resolved.

References

Primary source

Xiongfeng Zhan, Xueyi Huang and Huiqiu Lin, “Proof of Lew's conjecture on the spectral gaps of simplicial complexes”, arXiv:2407.10398 (2024).

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.