Al-Salam–Carlitz moment Pfaffian conjecture

From papers

Let Un(a)(x;q)U_n^{(a)}(x;q) be the Al-Salam–Carlitz polynomials, and let Gn(a;q)=k=0n[nk]qakG_n(a;q)=\sum_{k=0}^n\left[{{n}\atop{k}}\right]_q a^k be their moment sequence, where [nk]q=(q;q)n(q;q)k(q;q)nk\left[{{n}\atop{k}}\right]_q=\frac{(q;q)_n}{(q;q)_k(q;q)_{n-k}}. For n1n\geq1, set G1(a;q)=0G_{-1}(a;q)=0. Al-Salam–Carlitz moment Pfaffian conjecture. The identities

Pf((qi1qj1)Gi+j3(a;q))1i,j2n=an(n1)q13n/2(16n/221)(1)n4n/222n/2(n1)/2k=1n(q;q)2k1,\mathop{\rm Pf}\biggl((q^{i-1}-q^{j-1})G_{i+j-3}(a;q)\biggr)_{1\leq i,j\leq 2n}=a^{n(n-1)}q^{\frac13\lfloor n/2\rfloor(16\lfloor n/2\rfloor^2-1)-(-1)^n4\lfloor n/2\rfloor^2-2\lfloor n/2\rfloor\cdot\lfloor (n-1)/2\rfloor}\prod_{k=1}^{n}(q;q)_{2k-1},

and

Pf((qi1qj1)Gi+j2(a;q))1i,j2n=an(n1)q13n/2(16n/221)(1)n4n/22k=1n(q;q)2k1k=0nq(n2k)2/2[nk]q2ak\mathop{\rm Pf}\biggl((q^{i-1}-q^{j-1})G_{i+j-2}(a;q)\biggr)_{1\leq i,j\leq 2n}=a^{n(n-1)}q^{\frac13\lfloor n/2\rfloor(16\lfloor n/2\rfloor^2-1)-(-1)^n4\lfloor n/2\rfloor^2}\prod_{k=1}^{n}(q;q)_{2k-1}\sum_{k=0}^{n}q^{\lfloor (n-2k)^2/2\rfloor}\left[{{n}\atop{k}}\right]_{q^2}a^k

would hold, where x\lfloor x\rfloor is the greatest integer not exceeding xx. These are experimentally supported Pfaffian evaluations for a qq-moment sequence; their status is left open.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

Masao Ishikawa, Hiroyuki Tagawa and Jiang Zeng, “Pfaffian decomposition and a Pfaffian analogue of q-Catalan Hankel determinants”, arXiv:1011.5941 (2010).

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