Real-root and sign-distribution conjecture for characteristic polynomials in hyperbolic space

About 19 years old · traced to

Let A1,…,AmA_1,\ldots,A_m be m≥n+2m\geq n+2 points in HnH^n, and let α1,…,αm\alpha_1,\ldots,\alpha_m satisfy ∑i=1mαiAi=0\sum_{i=1}^m\alpha_iA_i=0. For 0≤k≤n0\leq k\leq n, let ckc_k be the constants defining the characteristic polynomial

f(x)=c0xn−c1xn−1+⋯+(−1)icixn−i+⋯+(−1)ncn.f(x)=c_{0}x^{n}-c_{1}x^{n-1}+\cdots+(-1)^{i}c_{i}x^{n-i}+\cdots+(-1)^{n}c_{n}.

Characteristic-polynomial conjecture. All roots of f(x)f(x) are real numbers. If m=n+2m=n+2, the points are in general position in HnH^n, and exactly ss of the αi\alpha_i are positive, then f(x)f(x) has s−1s-1 positive and n+1−sn+1-s negative roots.

This gives both a general real-root assertion and a more precise root-sign count in the minimally dependent, general-position case. The statement concerns the hyperbolic analogue of the characteristic-polynomial results established for Euclidean and spherical configurations; its resolution is not supplied here.

References

Primary source

Lizhao Zhang, “Rigidity and volume preserving deformation on degenerate simplices”, arXiv:math/0702601 (2018).

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.