# Tits group

Template:Pp-semi-indef In mathematics, the Tits group 2F4(2)′ (Template:IPA-fr) is a finite simple group of order 17971200 = 211 · 33 · 52 · 13 found by Template:Harvs.

The Ree groups 2F4(22n+1) were constructed by Template:Harvtxt, who showed that they are simple if n ≥ 1. The first member of this series 2F4(2) is not simple. It was studied by Template:Harvs who showed that its derived subgroup 2F4(2)′ of index 2 was a new simple group, the Tits group. The group 2F4(2) is a group of Lie type and has a BN pair, but the Tits group itself does not have a BN pair. Because the Tits group is not strictly a group of Lie type, it is sometimes regarded as a sporadic group.

## Properties

The Schur multiplier of the Tits group is trivial and its outer automorphism group has order 2, with the full automorphism group being the group 2F4(2).

The group 2F4(2) occurs as a maximal subgroup of the Rudvalis group, as the point stabilizer of the rank-3 permutation action on 4060 = 1 + 1755 + 2304 points.

The Tits group is one of the simple N-groups, and was overlooked in John G. Thompson's first announcement of the classification of simple N-groups, as it had not been discovered at the time. It is also one of the thin finite groups.

The Tits group was characterized in various ways by Template:Harvs and Template:Harvtxt.

## Maximal subgroups

Template:Harvtxt and Template:Harvtxt independently found the 8 classes of maximal subgroups of the Tits group as follows:

L3(3):2 Two classes, fused by an outer automorphism. These subgroup fix points of rank 4 permutation representations.

2.[28].5.4 Centralizer of an involution.

L2(25)

22.[28].S3

A6.22 (Two classes, fused by an outer automorphism)

52:4A4

## Presentation

The Tits group can be defined in terms of generators and relations by

${\displaystyle a^{2}=b^{3}=(ab)^{13}=[a,b]^{5}=[a,bab]^{4}=(ababababab^{-1})^{6}=1,\,}$

where [ab] is the commutator. It has an outer automorphism obtained by sending (ab) to (abbabababababbababababa).

## References

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