如果评估联接查询会终止吗？一个并不简单决定这个问题
Will My Favorite Chases Terminate if Evaluating Conjunctive Queries Does? One Does Not Simply Decide This
AI总结：
研究探讨了在支持可决定查询蕴含的规则类中，抽象规则类是否能变得具体，发现基于经典追逐变种终止性和有限树宽集的规则类并不满足这一条件。
摘要：
存在性规则是一种丰富数据库的正式主义，但使基本推理任务变得不可决定。为解决此问题，已识别出多种规则类，提供各种有用属性。例如，一类规则集保证追逐算法终止，从而保证存在有限的全模型。然而，这些类往往抽象而非具体：检查给定规则集是否属于此类可能不可决定。鉴于最研究的规则类设计用于数据库推理，从而确保可决定的联接查询蕴含，我们问：在支持可决定查询蕴含的规则类中，通常的抽象规则类是否变得具体？我们回答，对于基于所有经典追逐变种终止性的规则类和有限树宽集（BTS）类，答案是否定的。
英文摘要：
Existential rules are a prominent formalism to enrich a database with knowledge from the domain of interest, but make even basic reasoning tasks on the resulting knowledge base undecidable. To circumvent this, several classes of rules offering various useful properties have been identified. One such class, for instance, contains all sets of rules on which the chase algorithm always terminates, which guarantees the existence of a finite universal model. However, these classes are often abstract rather than concrete: it may be undecidable to check whether a given set of rules belongs to them. Given that the most studied classes of existential rules are designed for reasoning on databases, thus ensuring decidable conjunctive query entailment, we ask: Within a class that supports decidable query entailment, do the usual abstract classes become concrete? We answer in the negative for classes based upon the termination of all classical chase variants and for the bounded treewidth set (BTS) class.
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。
