Browsing by Author "02f7b341-657a-43e6-b5d6-9f5efb1522fa"

Now showing items 1-5 of 5

    • A more general theory of static approximations for conjunctive queries 
      Barceló, Pablo; Romero, Miguel; Zeume, Thomas (Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing, 2018)
      Conjunctive query (CQ) evaluation is NP-complete, but becomes tractable for fragments of bounded hypertreewidth. Approximating a hard CQ by a query from such a fragment can thus allow for an efficient approximate evaluation. ...
    • Regular queries on graph databases 
      Reutter, Juan L.; Romero, Miguel; Vardi, Moshe Y. (Springer, 2017)
      Graph databases are currently one of the most popular paradigms for storing data. One of the key conceptual differences between graph and relational databases is the focus on navigational queries that ask whether some nodes ...
    • Semantic optimization in tractable classes of conjunctive queries 
      Barceló Baeza, Pablo; Pieris, Andreas; Romero, Miguel (Association for Computing Machinery, 2017)
      This paper reports on recent advances in semantic query optimization. We focus on the core class of conjunctive queries (CQs). Since CQ evaluation is NP-complete, a long line of research has concentrated on identifying ...
    • The complexity of reverse engineering problems for conjunctive queries 
      Barceló Baeza, Pablo; Romero, Miguel (Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing, 2017)
      Reverse engineering problems for conjunctive queries (CQs), such as query by example (QBE) ordefinability, take a set of user examples and convert them into an explanatory CQ. Despite theirimportance, the complexity of ...
    • The homomorphism problem for regular graph patterns 
      Romero, Miguel; Barceló Baeza, Pablo; Vardi, Moshe Y. (IEEE, 2017)
      The evaluation of conjunctive regular path queries– which form the navigational core of the query languagesfor graph databases – raises challenges in the context of thehomomorphism problem that are ...