COL-Trees: Efficient Hierarchical Object Search in Road Networks

• URL: http://arxiv.org/abs/2601.22183v1
• Date: Wed, 28 Jan 2026 10:43:38 GMT
• Title: COL-Trees: Efficient Hierarchical Object Search in Road Networks
• Authors: Tenindra Abeywickrama, Muhammad Aamir Cheema, Sabine Storandt,
• Abstract summary: Location-based services rely heavily on efficient methods that search for relevant points-of-interest (POIs) near a given location.<n>While most existing techniques focus on retrieving nearby POIs for a single agent, these searchs do not translate to many other applications.<n>We present query algorithms that utilize COL-Trees to efficiently answer AkNN, kFN, and other queries.
• Score: 7.363671754306327
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Location-based services rely heavily on efficient methods that search for relevant points-of-interest (POIs) near a given location. A k Nearest Neighbor (kNN) query is one such example that finds the k closest POIs from an agent's location. While most existing techniques focus on retrieving nearby POIs for a single agent, these search heuristics do not translate to many other applications. For example, Aggregate k Nearest Neighbor (AkNN) queries require POIs that are close to multiple agents. k Farthest Neighbor (kFN) queries require POIs that are the antithesis of nearest. Such problems naturally benefit from a hierarchical approach, but existing methods rely on Euclidean-based heuristics, which have diminished effectiveness in graphs such as road networks. We propose a novel data structure, COL-Tree (Compacted Object-Landmark Tree), to address this gap by enabling efficient hierarchical graph traversal using a more accurate landmark-based heuristic. We then present query algorithms that utilize COL-Trees to efficiently answer AkNN, kFN, and other queries. In our experiments on real-world and synthetic datasets, we demonstrate that our techniques significantly outperform existing approaches, achieving up to 4 orders of magnitude improvement. Moreover, this comes at a small pre-processing overhead in both theory and practice.

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