Hankel total positivity conjecture for vincular pattern Classes 1 and 2
Hankel total positivity conjecture for vincular pattern Classes 1 and 2
For each , let and be the generating polynomials for the number of occurrences of vincular patterns in Class and Class , respectively. A polynomial sequence is coefficientwise Hankel totally positive in when every minor of its Hankel matrix has coefficients that are nonnegative polynomials in .
Hankel total positivity conjecture. The sequences of polynomials
are both coefficientwise Hankel totally positive with respect to the variable .
The unshifted sequences are not coefficientwise Hankel totally positive, while computations suggest that the shift restores this stronger positivity property. The claim is supported by finite tests but remains open.
Sources & referencesView supporting material
Primary source
Bishal Deb, “Cyclic sieving phenomena via combinatorics of continued fractions”, arXiv:2508.13709 (2025).
Additional references
5 papers in this index state this conjecture (2018–2025). The statement above is taken from the most recent of them; the others are arXiv:2507.18959, arXiv:2105.05583, arXiv:1807.01062, arXiv:1807.03271.
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