ATLAS: Unitary group U_{3}(7)
Order = 5663616 = 2^{7}.3.7^{3}.43.
Mult = 1.
Out = 2.
The following information is available for U_{3}(7):
Standard generators of U_{3}(7) are a and b where
a has order 2, b has order 3, ab has order 43
and ababb has order 4.
Type I standard generators of U_{3}(7):2 are c and d where
c is in class 7A, d is in class 4D and cd has order 6.
Type II standard generators of U_{3}(7):2 are e and f where
e is in class 2B, f has order 3, ef has order 8
and efeff has order 8.
THESE STANDARD GENERATORS (for U3(7):2) ARE STILL PROVISIONAL AND COULD STILL BE CHANGED.
An outer automorphism of U_{3}(7) can be taken to map
(a, b) to (a, bb).
To find standard generators for U_{3}(7):

Find any element of order 6, 12, 24 or 48 [i.e. order divisible by 6]. It
powers up to x of order 2 and y of order 3.
[The probability of success at each attempt is 5 in 16 (about 1 in 3).]

Find a conjugate a of x and a conjugate b of y such that ab has order 43 and ababb has order 4.
[The probability of success at each attempt is 96 in 2107 (about 1 in 22).]

Now a and b are standard generators for U_{3}(7).
To find standard generators for U_{3}(7).2:
Presentations of U_{3}(7) and U_{3}(7):2 (respectively) on their standard generators are given below.
< a, b  a^{2} = b^{3} =
(ab)^{43} = [a, b]^{4} =
[a, bababab]^{3} =
ab(ababab^{1})^{2}((ab)^{3}(ab^{1})^{3})^{3} = 1 >.
< c, d  c^{7} = d^{4} =
(cd)^{6} = ... = 1 >.
< e, f  e^{2} = f^{3} =
(ef)^{8} = [e, f]^{8} =
(efefef^{1})^{8} = ... = 1 >.
These presentations are available in Magma format as follows:
U_{3}(7) on a and b,
U_{3}(7):2 on c and d and
U_{3}(7):2 on e and f.
The representations of U_{3}(7) available are:

Permutation representations, including all primitive ones.

Permutations on 344 points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 688 points  imprimitive:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 1032 points  imprimitive:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 1376 points  imprimitive:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 2064 points  imprimitive:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 2107 points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 14749 points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 16856 points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Permutations on 43904 points:
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Faithful irreducibles in characteristic 2.

Dimension 42 over GF(2):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 258 over GF(2):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 344 over GF(2):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Faithful irreducibles in characteristic 3.

Dimension 42 over GF(3):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 43a over GF(3):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Faithful irreducibles in characteristic 7.

Dimension 6 over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).  reducible over GF(49).

Dimension 8 over GF(7):
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).  reducible over GF(49).

Dimension 20 over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).  reducible over GF(49).

Dimension 27 over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 30a over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).  reducible over GF(49).

Dimension 30b over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).  reducible over GF(49).

Dimension 37 over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 42 over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).  reducible over GF(49).

Dimension 48 over GF(7):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).  reducible over GF(49).

Faithful irreducibles in characteristic 43.

Dimension 42 over GF(43):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 43a over GF(43):
a and
b (Meataxe),
a and
b (Meataxe binary),
a and
b (GAP).

Dimension 43 over Z  NOT YET AVAILABLE:
a and b (Magma).
The representations of U_{3}(7):2 available are (NONE):

Permutations on 344 points:
c and
d (Meataxe),
c and
d (Meataxe binary),
c and
d (GAP).
The maximal subgroups of U_{3}(7) are:

7^{1+2}:48, with generators
a, (ab)^{6}(abb)^{2}._{ }

2.(L_{2}(7) × 4).2, with generators
a, (ab)^{3}(abb)^{2}(ab)^{3}.

8^{2}:S_{3}, with generators
a, abab(abb)^{3}abab(abb)^{2}ab.

L_{2}(7):2, with generators
a, (ba)^{4}bb.

43:3 = F_{129}, with generators
(ababababbab)^{2}, b.
The maximal subgroups of U_{3}(7):2 are [NOT YET FOUND]:

U_{3}(7), with generators
xxx.

7^{1+2}:48:_{7}2 = 7^{1+2}:(3 × SD_{32}), with generators
xxx.

2.(L_{2}(7) × 4).2.2, with generators
xxx.

8^{2}:D_{12}, with generators
xxx.

L_{2}(7):2 × 2, with generators
xxx.

43:6 = F_{258}, with generators
xxx.
The class representatives of the 48 conjugacy classes of Th are as follows:
 1A: identity or a^{2}.
 2A: a.^{ }
 3A: b.^{ }
 3B: (ababab^{2})^{6} or [a, bab]^{3}.
 3C: [a, babab]^{2}.
 4A: ababab^{2}ababab^{2}abab^{2}.
 4B: (abababab^{2}ab^{2})^{3}.
 5A: [a, b]^{2} or (abab^{2})^{2}.
 6A: [a, babab] or (ab)^{3}(ab^{2})^{3}.
 6B: (ab)^{6}(ab^{2})^{3}.
 6C: (ababab^{2})^{3}.
 7A: (ab)^{6}(ab^{2})^{6} or (abababab^{2})^{3}.
 8A: (ab)^{7}ab^{2} or ((ab)^{3}ab^{2}ab(ab^{2})^{2})^{3}.
 8B: ababababab^{2}(abab^{2}ab^{2}ab^{2})^{2} or (ab)^{9}(ab^{2})^{2}ab(ab^{2})^{3} or ((ab)^{7}ab^{2}ab(ab^{2})^{2})^{3}.
 9A: abab(abab^{2})^{3}ab^{2}ab^{2}.
 9B: ababababab^{2}ab^{2}abab^{2}ab^{2} or ((ab)^{5}ab^{2})^{3}.
 9C: (ababab^{2})^{2} or [a, bab].
 10A: [a, b] or abab^{2}.
 12A/B: abababab^{2}ababab^{2}ab^{2}.
 12C: (abababab^{2}ab^{2})^{2}ab^{2}.
 12D: abababab^{2}ab^{2}.
 13A: (ab)^{9}(ab^{2})^{3} or ab(abababab^{2})^{2}.
 14A: (ab)^{4}(ab^{2})^{3}.
 15A/B: (ab)^{6}ab^{2}abab^{2}ab^{2}.
 18A: (ab)^{10}(ab^{2})^{4} or abababab^{2}abab^{2}ab^{2}abab^{2} or (ab)^{5}(ababab^{2})^{2}.
 18B: ababab^{2}.
 19A: ab.^{ }
 20A: (ab)^{4}ab^{2}.
 21A: abababab^{2}.
 24A/B: (ab)^{3}ab^{2}ab(ab^{2})^{2}.
 24C/D: (ab)^{7}ab^{2}ab(ab^{2})^{2}.
 27A: (ab)^{5}ab^{2}.
 27B/C: (ab)^{7}ab^{2}abab(ab^{2})^{3} or ab(abababab^{2})^{2}abab^{2}.
 28A: (ab)^{6}ab^{2}.
 30A/B: (ab)^{5}ab^{2}abab^{2}ab^{2}.
 31A/B: (ab)^{5}(ab^{2})^{2}ab(ab^{2})^{4} or ab(ababab^{2})^{3}ab^{2}.
 36A: (ab)^{8}(ab^{2})^{2}.
 36B/C: ab(abababab^{2})^{2}ab^{2}ab^{2}.
 39A/B: (ab)^{8}ab^{2}ab(ab^{2})^{2}.
An element cannot be obtained as a power of an element of greater order
just if it is in class 18B or has order at least 19.
A set of generators for the maximal cyclic subgroups
can be obtained
by running this program [NOT THERE YET] on the standard
generators. All conjugacy classes can therefore be obtained as suitable
powers of these elements.
Problems of algebraic conjugacy are not dealt with.
Go to main ATLAS (version 2.0) page.
Go to classical groups page.
Go to old U3(7) page  ATLAS version 1.
Anonymous ftp access is also available.
See here for details.
Version 2.0 created on 13th October 2003.
Last updated 15.10.03 by JNB.
Information checked to
Level 0 on 13.10.03 by JNB.
R.A.Wilson, R.A.Parker and J.N.Bray.