Mao's rank and M2M_2-rank inequalities modulo 6 and 10

Let N(s,m,n)N(s,m,n) denote the number of partitions of nn whose Dyson rank is congruent to ss modulo mm. For partitions with no repeated odd parts, define the M2M_2 rank of a partition λ\lambda by

l(λ)2n(λ),\left\lceil \frac{l(\lambda)}{2} \right\rceil-n(\lambda),

and let N2(s,m,n)N_2(s,m,n) denote the number of such partitions whose M2M_2 rank is congruent to ss modulo mm. The inequalities below are asserted for the indicated ranges of nn: in the second, third, and seventh inequalities n1n\geq 1, and in the others n0n\geq 0.

Mao's conjectured inequalities. Computation evidence suggests that

N(0,10,5n)+N(1,10,5n)>N(4,10,5n)+N(5,10,5n),N(1,10,5n)+N(2,10,5n)N(3,10,5n)+N(4,10,5n),N2(0,10,5n)+N2(1,10,5n)>N2(4,10,5n)+N2(5,10,5n),N2(0,10,5n+4)+N2(1,10,5n+4)>N2(4,10,5n+4)+N2(5,10,5n+4),N2(1,10,5n)+N2(2,10,5n)>N2(3,10,5n)+N2(4,10,5n),N2(1,10,5n+2)+N2(2,10,5n+2)>N2(3,10,5n+2)+N2(4,10,5n+2),N2(0,6,3n+2)+N2(1,6,3n+2)>N2(2,6,3n+2)+N2(3,6,3n+2).\begin{aligned} N(0,10,5n)+N(1,10,5n)&>N(4,10,5n)+N(5,10,5n),\\ N(1,10,5n)+N(2,10,5n)&\geq N(3,10,5n)+N(4,10,5n),\\ N_2(0,10,5n)+N_2(1,10,5n)&>N_2(4,10,5n)+N_2(5,10,5n),\\ N_2(0,10,5n+4)+N_2(1,10,5n+4)&>N_2(4,10,5n+4)+N_2(5,10,5n+4),\\ N_2(1,10,5n)+N_2(2,10,5n)&>N_2(3,10,5n)+N_2(4,10,5n),\\ N_2(1,10,5n+2)+N_2(2,10,5n+2)&>N_2(3,10,5n+2)+N_2(4,10,5n+2),\\ N_2(0,6,3n+2)+N_2(1,6,3n+2)&>N_2(2,6,3n+2)+N_2(3,6,3n+2). \end{aligned}

The paper proves only a limited version of one of Mao's inequalities. The source states that the remaining three conjectures after other work are still open, so the full displayed collection is recorded as open.

Sources & referencesView supporting material

Primary source

Rupam Barman and Archit Pal Singh Sachdeva, “Proof of a Limited Version of Mao's Partition Rank Inequality using a Theta Function Identity”, arXiv:1605.06037 (2016).

Additional references

2 papers in this index state this conjecture (2015–2016). The statement above is taken from the most recent of them; the others are arXiv:1509.06039.

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