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Kazuki Shibata

Publications and source records attributed to Kazuki Shibata.

20 records · Page 2Linked to original sources

Roots of the Ehrhart polynomial of hypersimplices

The Ehrhart polynomial of the $d$-th hypersimplex $Δ(d,n)$ of order $n$ is studied. By computational experiments and a known result for $d=2$, we conjecture that the real part of every roots of the Ehrhart polynomial of $Δ(d,n)$ is negative and larger than $- \frac{n}{d}$ if $n \geq 2d$. In this paper, we show that the conjecture is true when $d=3$ and that every root $a$ of the Ehrhart polynomial of $Δ(d,n)$ satisfies $-\frac{n}{d} < {\rm Re} (a) < 1$ if $4 \leq d \ll n$.

math.CO↗

Smooth Fano polytopes whose Ehrhart polynomial has a root with large real part

The symmetric edge polytopes of odd cycles (del Pezzo polytopes) are known as smooth Fano polytopes. In this paper, we show that if the length of the cycle is 127, then the Ehrhart polynomial has a root whose real part is greater than the dimension. As a result, we have a smooth Fano polytope that is a counterexample to the two conjectures on the roots of Ehrhart polynomials.

math.CO↗