1/N phenomenon for some symmetry classes of the odd alternating sign matrices

Abstract

We consider the alternating sign matrices of the odd order that have some kind of central symmetry. Namely, we deal with matrices invariant under the half-turn, quarter-turn and flips in both diagonals. In all these cases, there are two natural structures in the centre of the matrix. For example, for the matrices invariant under the half-turn the central element is equal $\pm 1$. It was recently found that $A_{HT}^{+}(2m+1)/A_{HT}^{-}(2m+1)$=(m+1)/m. We conjecture that similar very simple relations are valid in the two remaining cases.

3 pages