The CTI–ITC polynomial equality conjecture for complete split graphs

Let Sn,dS_{n,d} be the complete split graph, and let Fn,dCTI(q,t)\mathfrak{F}_{n,d}^{CTI}(q,t) and Fn,dITC(q,t)\mathfrak{F}_{n,d}^{ITC}(q,t) denote the q,tq,t-CTI and q,tq,t-ITC polynomials, respectively. CTI–ITC equality conjecture.

Fn,dCTI(q,t)=Fn,dITC(q,t).\mathfrak{F}_{n,d}^{CTI}(q,t)=\mathfrak{F}_{n,d}^{ITC}(q,t).

Equality is known in some special cases, but the general case remains unresolved. It is equivalent, using the established equality of the q,tq,t-Schröder and q,tq,t-ITC polynomials, to the Schröder-polynomial formulation appearing below.

Sources & referencesView supporting material

Primary source

Henri Derycke, Mark Dukes and Yvan Le Borgne, “The sandpile model on the complete split graph: q,t-Schröder polynomials, sawtooth polyominoes, and a cycle lemma”, arXiv:2402.15372 (2025).

Progress summary

Never refreshed

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

Solutions 0

No solutions have been posted yet.