# 2-transitive group

In group theory, a branch of mathematics, a 2-transitive group is a transitive permutation group in which the stabilizer subgroup of every point acts transitively on the remaining points. Equivalently, a permutation group acts 2-transitively on a set ${\displaystyle S}$ if it acts transitively on the set of distinct ordered pairs ${\displaystyle \{(x,y)\in S\times S:x\neq y\}}$. Every 2-transitive group is a primitive group, but not conversely. Every Zassenhaus group is 2-transitive, but not conversely. The solvable 2-transitive groups were classified by Bertram Huppert and are described in the list of transitive finite linear groups. The insoluble groups were classified by (Hering 1985) using the classification of finite simple groups and are all almost simple groups.