Reversed higher-order quasi-Eulerian triangle total positivity conjecture

For r≥2r\geq 2, let QC(r)Q_{\rm C}^{(r)} and QS(r)Q_{\rm S}^{(r)} be the quasi-Eulerian cycle and subset triangles, respectively, and let MrevM^{\rm rev} denote reversal of the rows of a matrix MM. Quasi-Eulerian reversal conjecture. The matrices (QC(r))rev\left(Q_{\rm C}^{(r)}\right)^{\rm rev} and (QS(r))rev\left(Q_{\rm S}^{(r)}\right)^{\rm rev} are totally positive for all r≥2r\geq 2. These assertions were verified computationally for 3≤r≤103\leq r\leq 10 on leading 50×5050\times 50 submatrices, but remain open in general.

References

Primary source

Bishal Deb and Alan D. Sokal, “Higher-order Stirling cycle and subset triangles: Total positivity, continued fractions and real-rootedness”, arXiv:2507.18959 (2025).

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