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  • Association for Computing Machinery (ACM)  (3)
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  • Association for Computing Machinery (ACM)  (3)
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  • 1
    Online Resource
    Online Resource
    Association for Computing Machinery (ACM) ; 2020
    In:  ACM Transactions on Database Systems Vol. 45, No. 3 ( 2020-09-30), p. 1-42
    In: ACM Transactions on Database Systems, Association for Computing Machinery (ACM), Vol. 45, No. 3 ( 2020-09-30), p. 1-42
    Abstract: This article studies discovery of Graph Functional Dependencies (GFDs), a class of functional dependencies defined on graphs. We investigate the fixed-parameter tractability of three fundamental problems related to GFD discovery. We show that the implication and satisfiability problems are fixed-parameter tractable, but the validation problem is co-W[1]-hard in general. We introduce notions of reduced GFDs and their topological support, and formalize the discovery problem for GFDs. We develop algorithms for discovering GFDs and computing their covers. Moreover, we show that GFD discovery is feasible over large-scale graphs, by providing parallel scalable algorithms that guarantee to reduce running time when more processors are used. Using real-life and synthetic data, we experimentally verify the effectiveness and scalability of the algorithms.
    Type of Medium: Online Resource
    ISSN: 0362-5915 , 1557-4644
    RVK:
    Language: English
    Publisher: Association for Computing Machinery (ACM)
    Publication Date: 2020
    detail.hit.zdb_id: 196155-X
    detail.hit.zdb_id: 2006335-0
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Association for Computing Machinery (ACM) ; 2020
    In:  ACM Transactions on Database Systems Vol. 45, No. 2 ( 2020-06-30), p. 1-47
    In: ACM Transactions on Database Systems, Association for Computing Machinery (ACM), Vol. 45, No. 2 ( 2020-06-30), p. 1-47
    Abstract: Numeric inconsistencies are common in real-life knowledge bases and social networks. To catch such errors, we extend graph functional dependencies with linear arithmetic expressions and built-in comparison predicates, referred to as numeric graph dependencies (NGDs). We study fundamental problems for NGDs. We show that their satisfiability, implication, and validation problems are Σ p 2 -complete, Π p 2 -complete, and coNP-complete, respectively. However, if we allow non-linear arithmetic expressions, even of degree at most 2, the satisfiability and implication problems become undecidable. In other words, NGDs strike a balance between expressivity and complexity. To make practical use of NGDs, we develop an incremental algorithm IncDect to detect errors in a graph G using NGDs in response to updates Δ G to G . We show that the incremental validation problem is coNP-complete. Nonetheless, algorithm IncDect is localizable, i.e., its cost is determined by small neighbors of nodes in Δ G instead of the entire G . Moreover, we parallelize IncDect such that it guarantees to reduce running time with the increase of processors. In addition, to strike a balance between the efficiency and accuracy, we also develop polynomial-time parallel algorithms for detection and incremental detection of top-ranked inconsistencies. Using real-life and synthetic graphs, we experimentally verify the scalability and efficiency of the algorithms.
    Type of Medium: Online Resource
    ISSN: 0362-5915 , 1557-4644
    RVK:
    Language: English
    Publisher: Association for Computing Machinery (ACM)
    Publication Date: 2020
    detail.hit.zdb_id: 196155-X
    detail.hit.zdb_id: 2006335-0
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Online Resource
    Online Resource
    Association for Computing Machinery (ACM) ; 2023
    In:  ACM Transactions on Cyber-Physical Systems
    In: ACM Transactions on Cyber-Physical Systems, Association for Computing Machinery (ACM)
    Abstract: To realize the grand vision of automated driving in smart vehicle cyber-physical systems (CPS), one important task is to support the merging of connected automated vehicles (CAVs) from a metered-ramp to highway. Certain safety rules must be guaranteed. However, this demand is complicated by the inherently unreliable wireless communications. In this paper, we focus on the well adopted constant-time-headway (CTH) safety rule. We propose a highway and metered-ramp CAV collaborative merging protocol, and formally prove its guarantee of the CTH safety and liveness under arbitrary wireless data packet losses . These theoretical claims are further validated by our simulations. Furthermore, the simulation results also show significant improvements on the merging efficiency over other solution alternatives. Particularly, the merging success rates are more than \(99\% \) better in 11 out of 18 comparison pairs, and \(0\% \) (i.e. tied) \(\sim 71\% \) better in the remaining 7 comparison pairs.
    Type of Medium: Online Resource
    ISSN: 2378-962X , 2378-9638
    Language: English
    Publisher: Association for Computing Machinery (ACM)
    Publication Date: 2023
    detail.hit.zdb_id: 2887359-2
    Location Call Number Limitation Availability
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