单函数对象生成合取查询的映射等价和OID等价
Mapping-equivalence and oid-equivalence of single-function object-creating conjunctive queries
摘要：
连接数据库查询已经扩展了对象创建机制，以捕获重要的应用程序，如数据交换，数据集成和基于本体的数据访问。对象创建会在结果中生成新的对象标识符，这些标识符不属于源数据库中的常量集。新的对象标识符也可以被视为Skolem项。因此，对象创建合取查询也可以被视为受限的二阶元组生成依赖关系（SO tgds），在数据交换文献中考虑。在本文中，我们专注于类的单功能对象创建合取查询，或sifo的CQ为短。我们给出了一个新的特征的oid等价的sifo CQ，这是简单的比赫尔和吉川，并把问题的复杂性类NP。我们的特征是基于科恩的等价概念的连接查询的多重性。我们还解决了sifo CQ的逻辑蕴涵问题，表明这个问题也属于NP。Pichler等人的结果表明，更一般的SO tgds类的逻辑等价要么是不可判定的，要么是可判定的，但复杂度上界未知。
英文摘要：
Conjunctive database queries have been extended with a mechanism for object creation to capture important applications such as data exchange, data integration, and ontology-based data access. Object creation generates new object identifiers in the result, that do not belong to the set of constants in the source database. The new object identifiers can be also seen as Skolem terms. Hence, object-creating conjunctive queries can also be regarded as restricted second-order tuple-generating dependencies (SO tgds), considered in the data exchange literature. In this paper, we focus on the class of single-function object-creating conjunctive queries, or sifo CQs for short. We give a new characterization for oid-equivalence of sifo CQs that is simpler than the one given by Hull and Yoshikawa and places the problem in the complexity class NP. Our characterization is based on Cohen's equivalence notions for conjunctive queries with multiplicities. We also solve the logical entailment problem for sifo CQs, showing that also this problem belongs to NP. Results by Pichler et al. have shown that logical equivalence for more general classes of SO tgds is either undecidable or decidable with as yet unknown complexity upper bounds.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
