On symmetry group of Mollard code

Abstract

For a pair of given binary perfect codes C and D of lengths t and m respectively, the Mollard construction outputs a perfect code M(C,D) of length tm + t + m, having subcodes C1 and D2, that are obtained from codewords of C and D respectively by adding appropriate number of zeros. In this work we generalize of a result for symmetry groups of Vasilev codes [2] and find the group Stab_{D2}Sym(M(C,D)). The result is preceded by and partially based on a discussion of linearity of coordinate positions (points) in a nonlinear perfect code (non-projective Steiner triple system respectively).