Self-dual codes from extended orbit matrices of symmetric designs

We study codes spanned by the rows of an orbit matrix of a symmetric design with respect to an automorphism group that acts with all orbits of the same length. The dimension of such codes is discussed. We define an extended orbit matrix and show that under some condition the rows of the extended orbit matrix span a code that is self-dual with respect to a certain scalar product.

Based on joint work with Dean Crnković.