English

On Generalizations of a Conjecture of Kang and Park

Number Theory 2022-12-02 v2 Combinatorics

Abstract

Let Δd(a,)(n)=qd(a)(n)Qd(a,)(n)\Delta_d^{(a,-)}(n) = q_d^{(a)}(n) - Q_d^{(a,-)}(n) where qd(a)(n)q_d^{(a)}(n) counts the number of partitions of nn into parts with difference at least dd and size at least aa, and Qd(a,)(n)Q_d^{(a,-)}(n) counts the number of partitions into parts ±a(modd+3)\equiv \pm a \pmod{d + 3} excluding the d+3ad+3-a part. Motivated by generalizing a conjecture of Kang and Park, Duncan, Khunger, Swisher, and the second author conjectured that Δd(3,)(n)0\Delta_d^{(3,-)}(n)\geq 0 for all d1d\geq 1 and n1n\geq 1 and were able to prove this when d31d \geq 31 is divisible by 33. They were also able to conjecture an analog for higher values of aa that the modified difference function Δd(a,,)(n)=qd(a)(n)Qd(a,,)(n)0\Delta_{d}^{(a,-,-)}(n) = q_{d}^{(a)}(n) - Q_{d}^{(a,-,-)}(n) \geq 0 where Qd(a,,)(n)Q_{d}^{(a,-,-)}(n) counts the number of partitions into parts ±a(modd+3)\equiv \pm a \pmod{d + 3} excluding the aa and d+3ad+3-a parts and proved it for infinitely many classes of nn and dd. We prove that Δd(3,)(n)0\Delta_{d}^{(3,-)}(n) \geq 0 for all but finitely many dd. We also provide a proof of the generalized conjecture for all but finitely many dd for fixed aa and strengthen the results of Duncan, Khunger, Swisher, and the second author. We provide a conditional proof of a linear lower bound on dd for the generalized conjecture, which improves our unconditional result based on a conjectural modification of a recently proven conjecture of Alder. Using this modification, we obtain a strengthening of this generalization of Kang and Park's conjecture which remarkably allows aa as a part. Additionally, we provide asymptotic evidence that this strengthened conjecture holds.

Keywords

Cite

@article{arxiv.2206.04842,
  title  = {On Generalizations of a Conjecture of Kang and Park},
  author = {Ryota Inagaki and Ryan Tamura},
  journal= {arXiv preprint arXiv:2206.04842},
  year   = {2022}
}

Comments

version 2, minor edits and corrections;21 pages