The Computational Hardness of Finding Large Independent Sets in Sparse Random Hypergraphs

Core Concepts

There is a statistical-computational gap of a multiplicative factor of r^(-1/(r-1)) in the density of the largest independent set that can be found by low-degree polynomial algorithms in sparse random r-uniform hypergraphs and r-partite hypergraphs.

Abstract

The content discusses the algorithmic task of finding large independent sets in sparse Erdős–Rényi random r-uniform hypergraphs and r-partite hypergraphs.
Key highlights:

Krivelevich and Sudakov showed that the maximum independent set has density (r/(r-1)) * (log d/d)^(1/(r-1)) in the double limit n→∞ followed by d→∞.
The authors show that low-degree polynomial algorithms can find independent sets of density (1/(r-1)) * (log d/d)^(1/(r-1)) but no larger. This extends and generalizes earlier results for graphs.
The authors conjecture that this statistical-computational gap of a multiplicative factor of r^(-1/(r-1)) indeed holds for this problem.
The authors also explore the universality of this gap by examining r-partite hypergraphs. They prove an analogous computational threshold for finding large balanced independent sets in random r-uniform r-partite hypergraphs.
This work is the first to consider statistical-computational gaps of optimization problems on random hypergraphs, suggesting that these gaps persist for larger uniformities as well as across many models.

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Key Insights Distilled From

The Low-Degree Hardness of Finding Large Independent Sets in Sparse Random Hypergraphs

by Abhishek Dha... at arxiv.org 04-08-2024

https://arxiv.org/pdf/2404.03842.pdf

Deeper Inquiries

Can the statistical-computational gap of a multiplicative factor of r^(-1/(r-1)) be proven for polynomial-time algorithms, not just low-degree algorithms

The statistical-computational gap of a multiplicative factor of r^(-1/(r-1)) for polynomial-time algorithms can potentially be proven, although it may be more challenging compared to low-degree algorithms. The framework of low-degree algorithms, as discussed in the context, has been instrumental in proving such gaps for optimization problems on random hypergraphs. However, extending this gap to polynomial-time algorithms would require a more intricate analysis due to the increased complexity and computational power of polynomial-time algorithms.
To prove the statistical-computational gap for polynomial-time algorithms, one would need to consider the inherent limitations and capabilities of polynomial-time algorithms compared to low-degree algorithms. Polynomial-time algorithms have a broader scope and can potentially solve a wider range of problems efficiently, which might make it more challenging to establish a clear gap in performance for finding large independent sets in random hypergraphs.
Further research and analysis would be necessary to determine the feasibility and methodology of proving the statistical-computational gap of a multiplicative factor of r^(-1/(r-1)) for polynomial-time algorithms in the context of finding large independent sets in random hypergraphs.

What other optimization problems on random hypergraphs exhibit similar statistical-computational gaps, and can the techniques developed in this work be applied to analyze them

Several optimization problems on random hypergraphs exhibit similar statistical-computational gaps, where the hardness of finding optimal solutions is significantly greater than the tractability of finding approximate solutions. Some of these problems include the planted clique problem, community detection, and structured principal component analysis.
The techniques developed in the work discussed in the context, such as the Overlap Gap Property (OGP) and the framework of low-degree algorithms, can potentially be applied to analyze and understand these optimization problems on random hypergraphs. By adapting the OGP-based methods and the concept of low-degree algorithms to these problems, researchers can explore the statistical-computational gaps and the computational thresholds for optimization problems in a broader range of settings.
Applying these techniques to other optimization problems on random hypergraphs would involve understanding the specific characteristics and constraints of each problem, adapting the methodology to suit the problem's requirements, and conducting rigorous analyses to establish the statistical-computational gaps and computational thresholds effectively.

How do the structural properties of hypergraphs, such as the presence of odd cycles for r≥3, impact the computational complexity of finding large independent sets compared to the bipartite case

The structural properties of hypergraphs, such as the presence of odd cycles for r≥3, can significantly impact the computational complexity of finding large independent sets compared to the bipartite case.
In hypergraphs with odd cycles, the presence of additional constraints and dependencies among vertices can lead to more intricate relationships between edges and vertices. This complexity can make it more challenging to identify and construct large independent sets efficiently, as the interconnections between vertices in odd cycles introduce additional constraints that must be considered in the optimization process.
The computational complexity arising from odd cycles in hypergraphs can require more sophisticated algorithms and analytical techniques to navigate the intricate relationships and dependencies within the hypergraph structure. Understanding and addressing these structural properties are essential for developing effective algorithms and strategies for finding large independent sets in hypergraphs with odd cycles, highlighting the importance of considering the specific characteristics of the hypergraph when analyzing computational complexity.