[GAP Forum] A bug in CharacterTable("2.A11.2") mod 3

[Shunsuke Tsuchioka]

Hi,

I believe I found a bug in CharacterTable.

It is concluded that there exist 3-modular spin 
irreducible representations of dimension 1440-144=1296 
of the Schur cover of the symmetric group of degree 11 
in the paper:

Morris, A. O.(4-WALA); Yaseen, A. K.(4-WALA)
Decomposition matrices for spin characters of symmetric groups.
Proc. Roy. Soc. Edinburgh Sect. A 108 (1988), no. 1-2, 145

However, in gap, the command:

c:=CharacterTable("2.A11.2") mod 3;
Display(c);

displays the following infomation 
on the spin irreducible representations:

X.28      32   -32   .  .  .  .  .  -8   8  2  -2  4  -4  .   .  -1   1   .
X.29     144  -144   .  .  .  .  . -16  16 -1   1  4  -4  .   .   1  -1   .
X.30     144  -144   .  .  .  .  . -16  16 -1   1  4  -4  .   .   1  -1   .
X.31     528  -528   .  .  .  .  . -12  12 -2   2 -4   4  .   .   .   .   .
X.32     640  -640   .  .  .  .  .  20 -20  .   . -4   4  .   .   2  -2   .
X.33    1440 -1440   .  .  .  .  .  20 -20  .   . -2   2  .   .  -1   1   .
X.34    1440 -1440   .  .  .  .  .  20 -20  .   . -2   2  .   .  -1   1   .

I believe X.33 and X.34 are not irreducible and 
contain X.29 and X.30 as their composition factors.

Sincerely,
Shunsuke Tsuchioka