The Query Complexity of Local Search in Rounds on General Graphs

Fuente: arXiv
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Autori principali: Brânzei, Simina, Panageas, Ioannis, Paparas, Dimitris
Natura: Preprint
Pubblicazione: 2026
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author Brânzei, Simina
Panageas, Ioannis
Paparas, Dimitris
author_facet Brânzei, Simina
Panageas, Ioannis
Paparas, Dimitris
contents We analyze the query complexity of finding a local minimum in $t$ rounds on general graphs. More precisely, given a graph $G = (V,E)$ and oracle access to an unknown function $f : V \to \mathbb{R}$, the goal is to find a local minimum--a vertex $v$ such that $f(v) \leq f(u)$ for all $(u,v) \in E$--using at most $t$ rounds of interaction with the oracle. The query complexity is well understood on grids, but much less is known beyond. This abstract problem captures many optimization tasks, such as finding a local minimum of a loss function during neural network training. For each graph with $n$ vertices, we prove a deterministic upper bound of $O(t n^{1/t} (sΔ)^{1-1/t})$, where $s$ is the separation number and $Δ$ is the maximum degree of the graph. We complement this result with a randomized lower bound of $Ω(t n^{1/t}-t)$ that holds for any connected graph. We also find that parallel steepest descent with a warm start provides improved bounds for graphs with high separation number and bounded degree. To obtain our results, we utilized an advanced version of Gemini at various stages of our research. We discuss our experience in a methodology section.
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id arxiv_https___arxiv_org_abs_2601_13266
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Query Complexity of Local Search in Rounds on General Graphs
Brânzei, Simina
Panageas, Ioannis
Paparas, Dimitris
Computational Complexity
Data Structures and Algorithms
We analyze the query complexity of finding a local minimum in $t$ rounds on general graphs. More precisely, given a graph $G = (V,E)$ and oracle access to an unknown function $f : V \to \mathbb{R}$, the goal is to find a local minimum--a vertex $v$ such that $f(v) \leq f(u)$ for all $(u,v) \in E$--using at most $t$ rounds of interaction with the oracle. The query complexity is well understood on grids, but much less is known beyond. This abstract problem captures many optimization tasks, such as finding a local minimum of a loss function during neural network training. For each graph with $n$ vertices, we prove a deterministic upper bound of $O(t n^{1/t} (sΔ)^{1-1/t})$, where $s$ is the separation number and $Δ$ is the maximum degree of the graph. We complement this result with a randomized lower bound of $Ω(t n^{1/t}-t)$ that holds for any connected graph. We also find that parallel steepest descent with a warm start provides improved bounds for graphs with high separation number and bounded degree. To obtain our results, we utilized an advanced version of Gemini at various stages of our research. We discuss our experience in a methodology section.
title The Query Complexity of Local Search in Rounds on General Graphs
topic Computational Complexity
Data Structures and Algorithms
url https://arxiv.org/abs/2601.13266