Martinez-Savage's inversion-sequence conjecture for 3-nonnesting set partitions

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An inversion sequence of length nn is a sequence x=x1x2⋯xnx=x_1x_2\cdots x_n satisfying 0≤xi<i0\leq x_i<i for all 1≤i≤n1\leq i\leq n. A set partition of [n][n] is enhanced 3-nonnesting (respectively, enhanced 3-noncrossing) if it contains no enhanced nesting (respectively, crossing) of size 33. Martinez-Savage's conjecture. Inversion sequences of length nn with no weakly decreasing subsequence of length 33 are equinumerous with enhanced 3-nonnesting (3-noncrossing) set partitions of [n][n]. Lin confirmed this conjecture using generating trees, the obstinate kernel method and Zeilberger's algorithm.

References

Primary source

Sherry H. F. Yan, “Bijections for inversion sequences, ascent sequences and 3-nonnesting set partitions”, arXiv:1707.02408 (2017).

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