Generating-function conjecture for greedy (m,r)-Tamari intervals

For integers m1m\geq 1 and 1rm11\leq r\leq m-1, let d53cn(m,r)d53c^{(m,r)}_n be the set of greedy (m,r)(m,r)-Tamari intervals of size nn, and let

Fd53c(m,r)(t,x)=d53cd53c(m,r)(t,x;p1,p2,)F_{d53c^{(m,r)}}(t,x)=d53c_{d53c^{(m,r)}}(t,x;p_1,p_2,\ldots)

be their generating function with the weights defined in the source. Let Ω\Omega denote the operator used in the source, acting on the generating functions as indicated by the displayed identities. Generating-function conjecture for greedy (m,r)(m,r)-Tamari intervals. For 1rm11\leq r\leq m-1,

Fd53c(m,r)(t,x)=(Fd53c(m,0)(t,x)+Ω)r+1(1).F_{d53c^{(m,r)}}(t,x)=\bigl(F_{d53c^{(m,0)}}(t,x)+\Omega\bigr)^{r+1}(1).

For r=0r=0,

Fd53c(m,0)(t,x)=1+xt(Fd53c(m,0)(t,x)+Ω)m+1(1).F_{d53c^{(m,0)}}(t,x)=1+xt\bigl(F_{d53c^{(m,0)}}(t,x)+\Omega\bigr)^{m+1}(1).

Equivalently, for 0rm20\leq r\leq m-2,

Fd53c(m,r+1)(t,x)=(Fd53c(m,0)(t,x)+Ω)Fd53c(m,r)(t,x),F_{d53c^{(m,r+1)}}(t,x)=\bigl(F_{d53c^{(m,0)}}(t,x)+\Omega\bigr)F_{d53c^{(m,r)}}(t,x),

and

Fd53c(m,0)(t,x)=1+xt(Fd53c(m,0)(t,x)+Ω)Fd53c(m,m1)(t,x).F_{d53c^{(m,0)}}(t,x)=1+xt\bigl(F_{d53c^{(m,0)}}(t,x)+\Omega\bigr)F_{d53c^{(m,m-1)}}(t,x).

These identities are conjectured from numerical computation and describe the generating functions of the greedy (m,r)(m,r)-Tamari intervals.

Sources & referencesView supporting material

Primary source

Philippe Biane and Wenjie Fang, “Decomposition of Greedy Tamari Intervals and Bipartite Planar Maps”, arXiv:2607.01206 (2026).

Additional references

10 papers in this index state this conjecture (1998–2026). The statement above is taken from the most recent of them; the others are arXiv:2507.16908, arXiv:2504.06466, arXiv:2401.04026, arXiv:2112.15081, arXiv:1809.03123, arXiv:1411.6606, arXiv:1108.2859, arXiv:math/9806086, arXiv:math/9803091.

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