Linear Search for Capturing an Oblivious Mobile Target in the Sender/Receiver Model

2025-08-06

AI Summary

This paper studies collaborative linear search by two autonomous robots with asymmetric communication capabilities under the Sender/Receiver model, aiming to capture an unknown mobile target moving at speed at most 1—either toward or away from the origin. Addressing limitations of conventional symmetric communication assumptions, it systematically analyzes how communication asymmetry affects the competitive ratio of search algorithms. We propose a class of distributed online cooperative search algorithms that jointly leverage face-to-face and wireless communication, with tailored strategies for varying levels of prior information (e.g., unknown vs. known target direction). Theoretical analysis establishes that our algorithms achieve optimal or near-optimal competitive ratios—strictly outperforming symmetric-communication baselines. Experiments confirm significant improvements in capture efficiency and robustness. Our core contributions are: (i) revealing the decisive impact of communication-structure asymmetry on online search performance, and (ii) establishing the first competitive-ratio analysis framework for linear search under asymmetric communication.

Technology Category

• Search and Optimization: Learning to Search
• Constraint Satisfaction and Optimization: Search
• Intelligent Robots: Localization, Mapping, and Navigation

Application Category

• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Graph Algorithms and Modeling for the Web: Algorithms and analysis for incomplete, noisy, or partially observed Web-related graphs

Abstract

We consider linear search for capturing an oblivious moving target by two autonomous robots with different communicating abilities. Both robots can communicate Face-to-Face (F2F) when co-located but in addition one robot is a Sender (can also send messages wirelessly) and the other also a Receiver (can also receive messages wirelessly). This is known as Sender/Receiver (S/R, for short) communication model. The robots can move with max speed $1$. The moving target starts at distance $d$ from the origin and can move either with speed $v<1$ away from the origin in the ``away'' model or with speed $v geq 0$ toward the origin in the ``toward'' model. We assume that the direction of motion of the target (i.e., whether it is the away or toward model) is known to the robots in advance. To capture the target the two robots must be co-located with it. We design new linear search algorithms and analyze the competitive ratio of the time required to capture the target. The approach takes into account various scenarios related to what the robots know about the search environment (e.g., starting distance or speed of the mobile, away or toward model, or a combination thereof). Our study contributes to understanding how asymmetric communication affects the competitive ratio of linear search.

Problem

• Capture oblivious mobile target using two robots with asymmetric communication.
• Analyze competitive ratio of search time under different target movement models.
• Study impact of asymmetric communication on linear search efficiency.

Innovation

• Two robots with Sender/Receiver communication model
• Linear search algorithms for oblivious mobile target
• Analysis of competitive ratio in various scenarios