ATLAS: Exceptional group G_{2}(4)
Order = 251596800 = 2^{12}.3^{3}.5^{2}.7.13.
Mult = 2.
Out = 2.
See also ATLAS of Finite Groups, pp9799.
Standard generators of G_{2}(4) are a and b where
a is in class 2A, b is in class 5C/D, ab has order 13
and abb has order 13.
To ensure that b is in class 5C/D (and not class 5A/B), also
check that ababb has order 15.
The representations below are labelled such that b is in class 5C
of the Atlas of Brauer Characters.
Standard generators of the double cover 2.G_{2}(4) are preimages
A and B where B has order 5 and AB has order 13.
Standard generators of G_{2}(4):2 are c and d where
c is in class 2C, d is in class 4D, cd has order 13
and cdcddd has order 6.
Standard generators of the Atlas double cover 2.G_{2}(4):2 are
preimages C and D where CD has order 13.
(Similarly for the isoclinic, nonAtlas, double cover 2.G_{2}(4).2.)
The outer automorphism of G_{2}(4) can be realised by
the map taking (a, b) to (a, b^{2}).
To find standard generators of G_{2}(4):
 Find an element x of order 2 by taking a suitable power of any element of order 4, 8 or 12.
[The probability of success at each attempt is 33 in 256 (about 1 in 8).]
 Find an element y of order 5 by taking a suitable power of any element of order 5, 10 or 15.
[The probability of success at each attempt is 12 in 25 (about 1 in 2), and the porbability that y is in the right class is 1 in 2.]
 Find conjugates a of x and b of y such that ab has order 13 and abb has order 13.
[The probability of success at each attempt is 20 in 273 (about 1 in 14).]
 If ababb has order 15, then y was in the right class and a and b are standard generators of G_{2}(4). Otherwise ababb has order 10 and y was in the wrong class, so go back to Step 2.
To find standard generators of G_{2}(4).2:
 Find any element of order 2. Its seventh power, x say, is in class 2C.
[The probability of success at each attempt is 1 in 14 (or 1 in 7 if we search through outer elements only).]
 Er, I don't know how to find a 4Delement. 15/64 of the outer elements have order 4 or 12, and among these just 1/5 power into class 4D.
 Suppose we have obtained y in class 4D.
 Find conjugates c of x and d of y such that cd has order 13 and cdcddd has order 6.
[The probability of success at each attempt is 6 in 325 (about 1 in 54).]
 Now c and d are standard generators of G_{2}(4).2.
Alternatively, to find standard generators of G_{2}(4).2:
 Find any element of order 2. Its seventh power, x say, is in class 2C.
[The probability of success at each attempt is 1 in 14 (or 1 in 7 if we search through outer elements only).]
 Find an element y of order 13.
[The probability of success at each attempt is 1 in 13 (or 2 in 13 if we search through inner elements only).]
 Find conjugates c of x and z of y such that cz has order 4, czz has order 6, czzz has order 6.
[The probability of success at each attempt is 1 in 1600.]
 Now c and d = cz are standard generators of G_{2}(4).2.
The representations of G_{2}(4) available are:
 Some representations in characteristic 2:

Dimension 6 over GF(4)  the natural representation:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 6 over GF(4):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 14 over GF(4):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 14 over GF(4):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 36 over GF(2):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 64 over GF(4):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 64 over GF(4):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 84 over GF(4):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 84 over GF(4):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 196 over GF(2):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 384 over GF(4):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 896 over GF(4):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).
 Some representations in characteristic 3.

Dimension 64 over GF(3):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 78 over GF(3):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 286 over GF(3):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).
 Some representations in characteristic 5.

Dimension 65 over GF(5):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 78 over GF(5):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 350 over GF(5):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 363 over GF(5):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 650 over GF(5):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 65 over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 78 over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 65 over GF(13):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 78 over GF(13):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).
 Some faithful irreducibles in characteristic 0
 Dimension 65 over Z:
a and b (GAP).
 Dimension 78 over Z:
a and b (GAP).
 Dimension 350 over Z:
a and b (GAP).
 Some primitive permutation representations.

Permutations on 416 points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 1365[a] points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 1365[b] points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 2016 points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 2080 points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 20800 points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).
The representations of 2.G_{2}(4) available are:

Dimension 12 over GF(3):
A and
B (Meataxe),
A and
B (Meataxe binary),
A and
B (GAP).

Dimension 12 over GF(5):
A and
B (Meataxe),
A and
B (Meataxe binary),
A and
B (GAP).

Dimension 92 over GF(5):
A and
B (Meataxe),
A and
B (Meataxe binary),
A and
B (GAP).

Dimension 12 over GF(7):
A and
B (Meataxe),
A and
B (Meataxe binary),
A and
B (GAP).

Dimension 12 over GF(13):
A and
B (Meataxe),
A and
B (Meataxe binary),
A and
B (GAP).
 Some faithful irreducibles in characteristic 0
 Dimension 12 over Z[i]:
A and B (GAP).
The representations of G_{2}(4):2 available are:
 Some representations in characteristic 2.

Dimension 12 over GF(2):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).

Dimension 28 over GF(2):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).

Dimension 36 over GF(2):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).

Dimension 128 over GF(2):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).

Dimension 168 over GF(2):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).

Dimension 196 over GF(2):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).

Dimension 64 over GF(3):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).

Dimension 65 over GF(5):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).

Dimension 65 over GF(7):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).

Dimension 65 over GF(13):
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).
The representations of 2.G_{2}(4):2 available are:

Dimension 12 over GF(9):
C and
D (Meataxe),
C and
D (Meataxe binary),
C and
D (GAP).

Dimension 12 over GF(25):
C and
D (Meataxe),
C and
D (Meataxe binary),
C and
D (GAP).

Dimension 12 over GF(7):
C and
D (Meataxe),
C and
D (Meataxe binary),
C and
D (GAP).

Dimension 12 over GF(169):
C and
D (Meataxe),
C and
D (Meataxe binary),
C and
D (GAP).
The representations of the nonsplit 2.G_{2}(4).2 available are:

Dimension 12 over GF(3):
C and
D (Meataxe),
C and
D (Meataxe binary),
C and
D (GAP).
The maximal subgroups of G_{2}(4) are:
The maximal subgroups of G_{2}(4):2 are:
A set of generators for the maximal cyclic subgroups of
G_{2}(4)
can be obtained
by running this program on the standard
generators. All conjugacy classes can therefore be obtained as suitable
powers of these elements.
A set of generators for the maximal cyclic subgroups of
G_{2}(4):2
can be obtained
by running this program on the standard
generators. All conjugacy classes can therefore be obtained as suitable
powers of these elements.
Go to main ATLAS (version 2.0) page.
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Go to old G2(4) page  ATLAS version 1.
Anonymous ftp access is also available.
See here for details.
Version 2.0 created on 14th April 2000.
Last updated 06.04.04 by SJN.
Information checked to
Level 0 on 14.04.00 by RAW.
R.A.Wilson, R.A.Parker and J.N.Bray.