论文标题
计数查询答案通过DL-Lite知识库（扩展版）
Counting Query Answers over a DL-Lite Knowledge Base (extended version)
论文作者
论文摘要
计算查询的答案是几乎所有数据库管理系统支持的操作。在本文中，我们专注于在知识库（KB）上计数答案，该答案可能被视为具有有关正在考虑的领域的背景知识丰富的数据库。特别是，我们将作品放在本体介导的查询答案/基于本体的数据访问（OMQA/OBDA）的背景下，其中用于本体的语言是DL-Lite家族的成员，数据是（通常是虚拟的）断言集。我们研究了查询响应的数据复杂性，对于包括数字限制的DL-lite家族的不同成员以及与计数相对于其形状有所不同的计数（连接，分支，扎根）的变体的变体。我们通过提供PTIME和CONP下限以及PTIME和LOGSPACE的上限来改善现有结果。对于后一种情况，我们将一种新颖的查询重写技术定义为具有计数的一阶逻辑。
Counting answers to a query is an operation supported by virtually all database management systems. In this paper we focus on counting answers over a Knowledge Base (KB), which may be viewed as a database enriched with background knowledge about the domain under consideration. In particular, we place our work in the context of Ontology-Mediated Query Answering/Ontology-based Data Access (OMQA/OBDA), where the language used for the ontology is a member of the DL-Lite family and the data is a (usually virtual) set of assertions. We study the data complexity of query answering, for different members of the DL-Lite family that include number restrictions, and for variants of conjunctive queries with counting that differ with respect to their shape (connected, branching, rooted). We improve upon existing results by providing a PTIME and coNP lower bounds, and upper bounds in PTIME and LOGSPACE. For the latter case, we define a novel query rewriting technique into first-order logic with counting.
