论文标题
存在规则的保守扩展
Conservative Extensions for Existential Rules
论文作者
论文摘要
我们研究了元组生成依赖性（TGD）的T1，T2的问题，也称为存在规则，是否是T2是否是T1的保守扩展。我们考虑了两个自然的保守扩展概念，一种与数据库的结合查询答案有关，一个与Chated数据库之间的同态性有关。我们的主要结果是，对于线性TGD来说，这些问题是不可确定的，即使T1为空，也无法确定为保护的TGD，并且对于边界 - 一个TGD可决定。
We study the problem to decide, given sets T1,T2 of tuple-generating dependencies (TGDs), also called existential rules, whether T2 is a conservative extension of T1. We consider two natural notions of conservative extension, one pertaining to answers to conjunctive queries over databases and one to homomorphisms between chased databases. Our main results are that these problems are undecidable for linear TGDs, undecidable for guarded TGDs even when T1 is empty, and decidable for frontier-one TGDs.
