Enumeration conjectures for odd-order HTSASMs and DSASMs

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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,n−1)\delta(n,n-1) denote the partition associated with the corresponding irreducible representation of GL⁡2n+1\operatorname{GL}_{2n+1}, and let dim⁡GL⁡2n+1(δ(n,n−1))\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=3−n2(dim⁡GL⁡2n+1(δ(n,n−1)))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=3−n(n−1)/2dim⁡GL⁡2n+1(δ(n,n−1)).\#\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.

References

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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