An algorithm for the classification of twisted forms of toric varieties

Abstract

Let $K/k$ be a finite Galois extension, $G=\text{Gal}(K/k)$, $Σ$ be a fan in a lattice $N$ and $X_Σ$ be an associated toric variety over $k$. It is well known that the set of $K/k$-forms of $X_Σ$ is in bijection with $H^1(G,\text{Aut}_Σ^T)$, where $\text{Aut}_Σ^T$ is an algebraic group of toric automorphisms of $X_Σ$. In this paper, we suggest an algorithm to compute $H^1(G,\text{Aut}_Σ^T)$ and find that followings can be classified via this algorithm : $K/k$-forms of all toric surfaces, $K/k$-forms of all 3-dimensional affine toric varieties with no torus factor, $K/k$-forms of all 3-dimensional quasi-projective toric varieties when $K/k$ is cyclic.