English

Concerning Two Conjectures of Frick and Jafari

Combinatorics 2022-06-03 v1

Abstract

In 2022, Hamid Reza Daneshpajouh provided some counterexamples to the following conjecture of Florian Frick. \bf Conjecture. Let r3r \geq 3. Then, every hypergraph G{\cal G} over the ground set [n][n] satisfies χ(KGr(Grstable))cdr(G)r1. \chi \left({\rm KG}^r ({\cal G}_{r-{\rm stable}})\right) \geq \left\lceil \frac{{\rm cd}^r ({\cal G})}{r-1} \right\rceil . In this paper, we improve Danashpajouh's results. Also, we provide several counterexamples to the following recent conjecture of Amir Jafari. Conjecture. If sr2s \geq r \geq 2, then for any hypergraph G{\cal G} with vertex set [n][n] we have χ(KGr(Gsstable))ecds(G)r1. \chi \left({\rm KG}^r ({\cal G}_{s-{\rm stable}})\right) \geq \left\lceil \frac{{\rm ecd}^s ({\cal G})}{r-1} \right\rceil .

Keywords

Cite

@article{arxiv.2206.00836,
  title  = {Concerning Two Conjectures of Frick and Jafari},
  author = {Saeed Shaebani},
  journal= {arXiv preprint arXiv:2206.00836},
  year   = {2022}
}

Comments

This is a very preliminary draft