Current browse context:
cs.DS
Change to browse by:
References & Citations
Computer Science > Data Structures and Algorithms
Title: A degree 4 sum-of-squares lower bound for the clique number of the Paley graph
(Submitted on 4 Nov 2022 (v1), last revised 25 Apr 2024 (this version, v2))
Abstract: We prove that the degree 4 sum-of-squares (SOS) relaxation of the clique number of the Paley graph on a prime number $p$ of vertices has value at least $\Omega(p^{1/3})$. This is in contrast to the widely believed conjecture that the actual clique number of the Paley graph is $O(\mathrm{polylog}(p))$. Our result may be viewed as a derandomization of that of Deshpande and Montanari (2015), who showed the same lower bound (up to $\mathrm{polylog}(p)$ terms) with high probability for the Erd\H{o}s-R\'{e}nyi random graph on $p$ vertices, whose clique number is with high probability $O(\log(p))$. We also show that our lower bound is optimal for the Feige-Krauthgamer construction of pseudomoments, derandomizing an argument of Kelner. Finally, we present numerical experiments indicating that the value of the degree 4 SOS relaxation of the Paley graph may scale as $O(p^{1/2 - \epsilon})$ for some $\epsilon > 0$, and give a matrix norm calculation indicating that the pseudocalibration proof strategy for SOS lower bounds for random graphs will not immediately transfer to the Paley graph. Taken together, our results suggest that degree 4 SOS may break the "$\sqrt{p}$ barrier" for upper bounds on the clique number of Paley graphs, but prove that it can at best improve the exponent from $1/2$ to $1/3$.
Submission history
From: Dmitriy Kunisky [view email][v1] Fri, 4 Nov 2022 19:05:04 GMT (267kb,D)
[v2] Thu, 25 Apr 2024 20:38:10 GMT (406kb,D)
Link back to: arXiv, form interface, contact.