Bart Bogaerts ; Maxime Jakubowski ; Jan Van den Bussche - Expressiveness of SHACL Features and Extensions for Full Equality and Disjointness Tests

lmcs:10442 - Logical Methods in Computer Science, February 28, 2024, Volume 20, Issue 1 - https://doi.org/10.46298/lmcs-20(1:16)2024
Expressiveness of SHACL Features and Extensions for Full Equality and Disjointness TestsArticle

Authors: Bart Bogaerts ; Maxime Jakubowski ; Jan Van den Bussche

    SHACL is a W3C-proposed schema language for expressing structural constraints on RDF graphs. Recent work on formalizing this language has revealed a striking relationship to description logics. SHACL expressions can use three fundamental features that are not so common in description logics. These features are equality tests; disjointness tests; and closure constraints. Moreover, SHACL is peculiar in allowing only a restricted form of expressions (so-called targets) on the left-hand side of inclusion constraints. The goal of this paper is to obtain a clear picture of the impact and expressiveness of these features and restrictions. We show that each of the four features is primitive: using the feature, one can express boolean queries that are not expressible without using the feature. We also show that the restriction that SHACL imposes on allowed targets is inessential, as long as closure constraints are not used. In addition, we show that enriching SHACL with "full" versions of equality tests, or disjointness tests, results in a strictly more powerful language.


    Volume: Volume 20, Issue 1
    Published on: February 28, 2024
    Accepted on: February 1, 2024
    Submitted on: December 8, 2022
    Keywords: Computer Science - Logic in Computer Science

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