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Start date: 2023Subject: search.filters.subject.Graph Traversal

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    Item type:Publication,
    Answer Set Programming for Bus Route Finding: A Case Study in Bangkok, Thailand
    (2026-01-01)
    Racharak, Teeradaj
    ;
    Mon, Su Yee
    ;
    Chawuthai, Rathachai
    Finding user-satisfied bus routes subject to the minimal travel time and the number of route transfers is a challenging problem in transportation networks. In our context, bus routes and bus stations form a directed graph. Thus, a solution to finding the user-satisfied bus routes is a route path between two given stations satisfying a collection of different user's constraints. While this problem could be related to existing research, such as, the study of graph traversal and path finding algorithms. We show that our problem is more suited to formalizing the navigation system in terms of several related answer set programs (ASPs), where each module has its own isolated function, rather than treating like common graph traversal problems such as the well-known Dijkstra's algorithm, which only provides a statically single solution with lowest cost. Our empirical study with a real-world bus network data confirms that our ASPs encoding works in producing a wide range of high-quality solutions, offering more flexibilities between different optimization criteria, compared with the fixed Dijkstra's optimization results. The findings show promise for extending to richer transit representations and optimization objectives beyond the two considered here.
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    Modelling an RDF Knowledge Graph with Transitivity and Symmetry for Bus Route Path Finding
    (2023-12-16)
    Chawuthai, Rathachai
    ;
    Kertkeidkachorn, Natthawut
    ;
    Racharak, Teeradaj
    A key property of Linked Data is the representation and publication of data as an inter-connected labelled graph where different resources linked to each other form a network of meaningful information. A problem of path finding can be seen as searching important relationships between resources, such as, looking for chains of intermediate nodes. In this paper, we tackle this problem in the context of public transport navigation system, where we aim to find candidates of bus route path given two bus stations. We model a novel lightweight bus network as Resource Description Framework (RDF) triples of directed bus lines and walking paths between connected stations. Indeed, we demonstrate that lightweight bus network can be achieved by exploiting the sub-property of RDF Schema (RDFS) and the transitivity and symmetry provided by Web Ontology Language (OWL). We also perform a scalability test of our approach using a real-world bus network in Bangkok, Thailand. Various patterns of SPARQL Protocol and RDF Query Language (SPARQL) query statements are validated, showing the usefulness of the RDF model. The further step of this paper is to work with bus schedules and travel time analysis in order to select some proper candidates for users through an application.