a r t i c l e i n f o a b s t r a c t Given a Galois extension we relate subfield subcodes with trace codes showing that a code is invariant under the Galois group if and only if its restriction coincides with the trace code.
The generalized Petersen graphs (GPGs) which have been invented by Watkins, may serve for perhaps the simplest nontrivial examples of " galactic " graphs, i.e. those with a nice property of having a semiregular automorphism. Some of them are also vertex-transitive or even more highly symmetric, and some are Cayley graphs. In this paper, we study a further… (More)
We describe an algorithm for obtaining the central primitive idempotents of the algebra associated with a monomial representation. As a consequence, we obtain its irreducible constituents. This is implemented in MAGMA, using an algorithm based on Dixon's modular approach. In the case of permutation representations, we get a simplified version of the… (More)