On a duality for codes over non-abelian groups

This work is motivated by a well-known open problem in coding theory, asking whether there is a duality theory for codes over non-abelian groups, see Dougherty et al. (Contemp Math 634:79–99, 2015). We prove that such a duality cannot be induced by a duality of a group lattice, and then study a variation that reduces to a group theoretic investigation: We say a finite group of order m has a layer-symmetric lattice if for every divisor d of m there is a bijection between the subgroups of order d and the subgroups of order m/d. We prove that every such group is nilpotent, and then investigate the class of finite p-groups with a layer-symmetric lattice.