7
$\begingroup$

Question: We say that a convex lattice polytope $P\subset \mathbb{R}^d$ is a smooth Fano polytope if:

  1. The origin is contained in the interior of $P$
  2. The vertices of every facet of $P$ are a $\mathbb{Z}$-basis of $\mathbb{Z}^d$

Now, suppose we have a set $V=\{v_1,\ldots,v_n\}\subset \mathbb{Z}^d$. What is an (preferentially efficient) algorithm for deciding if the convex hull $\text{conv}(V)$ is a smooth Fano polytope?

Motivation:
I've read a paper that gives an algorithm to classify all smooth Fano polytopes given the dimension $d$ as input (An algorithm for the classification of smooth Fano polytopes by Mikkel Øbro), and while trying to implement said algorithm I discovered I don't know how to solve this question.
For those who are curious, I want to use the algorithm to help me gain some intuition about toric varieties, and use it to compute known invariants and test conjectures.

  • 0
    What's wrong with Gaussian elimination?2012-02-29

1 Answers 1

2

After you have found the facets of $P$, you can check if $d$ points form a $\mathbb Z$ bases by calculating their determinant which has to be $\pm 1$.

(The determinant is the volume of the fundamental domain and is the inverse of the density of lattice points. A sublattice is the integer lattice if and only if the density is the same.)