On the Intersection of ${BBZ }_{2} {BBZ }_{4}$ -Additive Perfect Codes

The intersection problem for Z₂Z₄-additive (extended and nonextended) perfect codes, i.e., which are the possibilities for the number of codewords in the intersection of two Z₂Z₄-additive codes C₁ and C₂ of the same length, is investigated. Lower and upper bounds for the intersection number are computed and, for any value between these bounds, codes which have this given intersection value are constructed. For all these Z₂Z₄-additive codes C₁ and C₂, the abelian group structure of the intersection codes C₁ cap C₂ is characterized. The parameters of this Abelian group structure corresponding to the intersection codes are computed and lower and upper bounds for these parameters are established. Finally, for all possible parameters between these bounds, constructions of codes with these parameters for their intersections are given.