## Constructions of Primitive Formally Dual Pairs Having Subsets with Unequal Sizes. (arXiv:1810.05433v1 [math.CO])

The concept of formal duality was proposed by Cohn, Kumar and Sch\"urmann,
which reflects an unexpected symmetry among energy-minimizing periodic
configurations. This formal duality was later on translated into a purely
combinatorial property by Cohn, Kumar, Reiher and Sch\"urmann, where the
corresponding combinatorial object was called formally dual pair. Almost all
known examples of primitive formally dual pairs satisfy that the two subsets
have the same size. Indeed, prior to this work, there is only one known example
having subsets with unequal sizes in $\mathbb{Z}_2 \times \mathbb{Z}_4^2$.
Motivated by this example, we propose a lifting construction framework and a
recursive construction framework, which generate new primitive formally dual
pairs from known ones. As an application, for $m \ge 2$, we obtain $m+1$
pairwise inequivalent primitive formally dual pairs in $\mathbb{Z}_2 \times
\mathbb{Z}_4^{2m}$, which have subsets with unequal sizes.查看全文