Paper detail

On the size of lattice simplices with a single interior lattice point

Let $\mathcal{T}^d(1)$ be the set of all $d$-dimensional simplices $T$ in $\real^d$ with integer vertices and a single integer point in the interior of $T$. It follows from a result of Hensley that $\mathcal{T}^d(1)$ is finite up to affine transformations that preserve $\mathbb{Z}^d$. It is known that, when $d$ grows, the maximum volume of the simplices $T \in \cT^d(1)$ becomes extremely large. We improve and refine bounds on the size of $T \in \mathcal{T}^d(1)$ (where by the size we mean the volume or the number of lattice points). It is shown that each $T \in \mathcal{T}^d(1)$ can be decomposed into an ascending chain of faces whose sizes are `not too large'. More precisely, if $T \in \mathcal{T}^d(1)$, then there exist faces $G_1 \subseteq ... \subseteq G_d=T$ of $T$ such that, for every $i \in \{1,...,d\}$, $G_i$ is $i$-dimensional and the size of $G_i$ is bounded from above in terms of $i$ and $d$. The bound on the size of $G_i$ is double exponential in $i$. The presented upper bounds are asymptotically tight on the log-log scale.