The invariant Hermitian lattices in the Steinberg module of SL2(q) are described. These lattices are connected with generalized quadratic residue codes over a field of four elements. The isometry groups of invariant lattices are calculated. In particular, 13-dimensional unimodular lattices over Eisenstein numbers with minimum norm 3 and automorphism group Z6 × PSP6(3) are obtained.
ASJC Scopus subject areas
- Algebra and Number Theory