# On the irreducible action of psl(2, r) on the 3-dimensional einstein universe

## TL;DR

This paper classifies the orbits of the irreducible PSL(2, R) action on the 3D Einstein universe, contributing to the broader understanding of symmetry actions in Lorentzian geometry.

## Contribution

It completes the classification of irreducible PSL(2, R) actions on Ein 1,2, advancing the understanding of their orbit structures.

## Key findings

- Describes the orbit structure of PSL(2, R) on Ein 1,2
- Completes previous classification work
- Contributes to the broader classification of cohomogeneity one actions

## Abstract

We describe the orbits of the irreducible action of PSL(2, R) on the 3-dimensional Einstein universe Ein 1,2. This work completes the study in [2], and is one element of the classification of cohomo-geneity one actions on Ein 1,2 ([5]).