# Lie algebras of vertical derivations on semiaffine varieties with torus actions

## TL;DR

This paper classifies vertical additive group actions on proper varieties with torus actions and provides criteria for when their infinitesimal generators form finite-dimensional Lie algebras.

## Contribution

It introduces a classification of vertical additive group actions on proper varieties with torus actions and establishes a criterion for finite-dimensional Lie algebra generation.

## Key findings

- Classification of vertical additive group actions on proper varieties.
- Criterion for infinitesimal generators to form finite-dimensional Lie algebras.
- Insight into the structure of derivations on varieties with torus actions.

## Abstract

Let X be a normal variety endowed with an algebraic torus action. An additive group action $\alpha$ on X is called vertical if a general orbit of $\alpha$ is contained in the closure of an orbit of the torus action and the image of the torus normalizes the image of $\alpha$ in Aut(X). Our first result in this paper is a classification of vertical additive group actions on X under the assumption that X is proper over an affine variety. Then we establish a criterion as to when the infinitesimal generators of a finite collection of additive group actions on X generate a finite-dimensional Lie algebra inside the Lie algebra of derivations of X.