Enumeration conjectures for odd-order HTSASMs and DSASMs

Let nn be a nonnegative integer. An HTSASM is a half-turn-symmetric alternating sign matrix, and a DSASM is a diagonally symmetric alternating sign matrix. Let δ(n,n1)\delta(n,n-1) denote the partition associated with the corresponding irreducible representation of GL2n+1\operatorname{GL}_{2n+1}, and let dimGL2n+1(δ(n,n1))\dim \operatorname{GL}_{2n+1}(\delta(n,n-1)) denote its dimension.

Enumeration conjectures for odd-order HTSASMs and DSASMs. The number of (2n+1)×(2n+1)(2n+1)\times(2n+1) HTSASMs is

#A2n+1HTS=3n2(dimGL2n+1(δ(n,n1)))2,\#\mathcal{A}^{\mathrm{HTS}}_{2n+1}=3^{-n^2}\left(\dim \operatorname{GL}_{2n+1}(\delta(n,n-1))\right)^2,

and the number of (2n+1)×(2n+1)(2n+1)\times(2n+1) DSASMs is

#A2n+1DS=3n(n1)/2dimGL2n+1(δ(n,n1)).\#\mathcal{A}^{\mathrm{DS}}_{2n+1}=3^{-n(n-1)/2}\dim \operatorname{GL}_{2n+1}(\delta(n,n-1)).

The paper states that the enumeration problems for odd-order HTSASMs and DSASMs remain open and presents these as reformulations of conjectures from the cited literature.

Sources & referencesView supporting material

Primary source

Soichi Okada, “Enumeration of Symmetry Classes of Alternating Sign Matrices and Characters of Classical Groups”, arXiv:math/0408234 (2004).

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