论文标题
一致性和与RDF数据交换有关的某些答案以及形状约束
Consistency and Certain Answers in Relational to RDF Data Exchange with Shape Constraints
论文作者
论文摘要
我们研究了来自R2RML启发的RDF图的数据交换，并增加了目标形状模式。我们研究一致性的问题，即检查每个源实例都可以接受解决方案，并确定某些查询答案，即找到每个解决方案中存在的答案。我们确定与RDF数据交换的建设性关系类别，该类别使用IRI构造函数和完整的TGD（没有存在变量）来源来依赖。我们表明一致性问题是综合性的。我们介绍了通用仿真解决方案的概念，该解决方案允许计算在模拟下可靠的任何鲁棒的查询类别的某些查询答案。一个这样的类是嵌套的正则表达式（NRE），即不使用逆操作。使用通用仿真解决方案，可允许对正向NRE的某些答案进行计算（数据复杂性）。最后，我们提出了许多结果，这些结果表明，放松提出的框架的限制会导致复杂性的增加。
We investigate the data exchange from relational databases to RDF graphs inspired by R2RML with the addition of target shape schemas. We study the problems of consistency i.e., checking that every source instance admits a solution, and certain query answering i.e., finding answers present in every solution. We identify the class of constructive relational to RDF data exchange that uses IRI constructors and full tgds (with no existential variables) in its source to target dependencies. We show that the consistency problem is coNP-complete. We introduce the notion of universal simulation solution that allows to compute certain query answers to any class of queries that is robust under simulation. One such class are nested regular expressions (NREs) that are forward i.e., do not use the inverse operation. Using universal simulation solution renders tractable the computation of certain answers to forward NREs (data-complexity). Finally, we present a number of results that show that relaxing the restrictions of the proposed framework leads to an increase in complexity.
