The Gram determinant conjecture for Möbius-band diagrams with one crosscap curve

Let R=Z[A±1,w,x,y,z]R=\mathbb{Z}[A^{\pm1},w,x,y,z]. For n1n\geq 1, let Dn(Mb)1D_n^{(Mb)_1} denote the Gram determinant of type (Mb)1(Mb)_1, where the Gram matrix is formed from crossingless-connection diagrams on the Möbius band with the associated bilinear form. Let dd, ww, xx, yy, and zz be the parameters occurring in that form, and let TkT_k and SkS_k denote the Chebyshev polynomials used in the source. The Gram determinant conjecture. For n1n\geq 1,

Dn(Mb)1=[(dz)((d+z)w2xy)](2nn1)k=2n(Tk(d)2z2)(2nnk)k=2n(d24)(2nnk)(Sk1(d))2(2nnk).D^{(Mb)_1}_n=\left[(d-z)((d+z)w-2xy)\right]^{\binom{2n}{n-1}}\prod_{k=2}^n\left(T_k(d)^2-z^2\right)^{\binom{2n}{n-k}}\prod_{k=2}^n(d^2-4)^{\binom{2n}{n-k}}\left(S_{k-1}(d)\right)^{2\binom{2n}{n-k}}.

The formula is presented as a conjectured closed form for the Gram determinant; the source also relates its final product factors to the determinant in the one-crosscap sector.

Sources & referencesView supporting material

Primary source

Anthony Christiana, Dionne Ibarra and Gabriel Montoya-Vega, “Chebyshev polynomials and Gram determinants from the Möbius band”, arXiv:2504.16439 (2025).

Additional references

3 papers in this index state this conjecture (2021–2025). The statement above is taken from the most recent of them; the others are arXiv:2304.05616, arXiv:2104.01417.

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