© 2001 by London Mathematical Society
© The London Mathematical Society
KazhdanLusztig Cells, q-Schur Algebras and James' Conjecture
Institut Girard Desargues Bâtiment 101, Université Lyon 1 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex, France, geck{at}desargues.univ-lyon1.fr
Received 4 October 1999. Revision received 5 April 2000.
We consider the DipperJames q-Schur algebra Sq(n, r)k, defined over a field k and with parameter q
0. An understanding of the representation theory of this algebra is of considerable interest in the representation theory of finite groups of Lie type and quantum groups; see, for example, [6] and [11]. It is known that Sq(n, r)k is a semisimple algebra if q is not a root of unity. Much more interesting is the case when Sq(n, r)k is not semisimple. Then we have a corresponding decomposition matrix which records the multiplicities of the simple modules in certain standard modules (or Weyl modules). A major unsolved problem is the explicit determination of these decomposition matrices.