Qi Chen's Gram determinant conjecture for the Möbius band

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Let R=Z[A±1,w,x,y,z]R=\mathbb{Z}[A^{\pm1},w,x,y,z]. For n≥1n\geq1, let DnMb(d,w,x,y,z)D_n^{\mathit{Mb}}(d,w,x,y,z) be the Gram determinant of type Mb\mathit{Mb}. Let TkT_k and SkS_k denote the Chebyshev polynomials used in the source, and let Dn,iD_{n,i} encode the contribution from diagrams with ii curves passing through the crosscap. Qi Chen's conjecture. For n≥1n\geq1,

DnMb(d,w,x,y,z)=∏k=1n(Tk(d)+(−1)kz)(2nn−k)∏k=1k oddn((Tk(d)−(−1)kz)Tk(w)−2xy)(2nn−k)D^{\mathit{Mb}}_n(d,w,x,y,z)=\prod_{k=1}^n\left(T_k(d)+(-1)^kz\right)^{\binom{2n}{n-k}} \prod_{\substack{k=1\\ k\text{ odd}}}^n\left(\left(T_k(d)-(-1)^kz\right)T_k(w)-2xy\right)^{\binom{2n}{n-k}} ⋅∏k=1k evenn((Tk(d)−(−1)kz)Tk(w)−2(2−z))(2nn−k)∏i=1nDn,i,\cdot\prod_{\substack{k=1\\ k\text{ even}}}^n\left(\left(T_k(d)-(-1)^kz\right)T_k(w)-2(2-z)\right)^{\binom{2n}{n-k}}\prod_{i=1}^nD_{n,i},

where

Dn,i=∏k=1+in((d2−4)(Sk−1(d))2(2nn−k)),D_{n,i}=\prod_{k=1+i}^n\left((d^2-4)(S_{k-1}(d))^{2\binom{2n}{n-k}}\right),

and ii represents the number of curves passing through the crosscap. The displayed formula is given as a future-direction conjecture and is described as a restatement associated with Qi Chen.

References

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

4 papers in this index state this conjecture (2019–2025). The statement above is taken from the most recent of them; the others are arXiv:2402.09704, arXiv:2304.05616, arXiv:1905.07834.

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