Ontology-Mediated Query Answering (OMQA) is a well-established framework to answer queries over Knowledge Graphs (KGs), enriched with rdfs or owl ontologies. OMQA was originally designed for Unions of Conjunctive Queries (UCQs), and based on certain answers. More recently, OMQA has been extended to sparql queries, but to our knowledge, none of the efforts made in this direction (either in the literature, or the so-called W3C sparql entailment regimes) is able to capture both certain answers for UCQs and the standard interpretation of sparql over a plain graph. We formalize these as requirements to be met by any semantics that aims at conciliating certain answers and sparql answers, and extend these with three additional requirements. Then we define two semantics that satisfies all requirements for sparql queries with select, union, join, and optional. Finally, we investigate the combined complexity of query answering under these semantics over a KG enriched with a ${\mathit{\text{DL-Lite}}}_{\mathcal{R}}$ ontology, showing that for several fragments of sparql, known upper-bounds for query answering over a plain KG are matched.

本体中介查询应答（OMQA）是一个完善的框架，用于回答丰富了rdfs或owl本体的知识图（KG）。OMQA最初是为联合查询联合会（UCQs）设计的，并且基于某些答案。最近，OMQA已扩展到sparql查询，但是据我们所知，在此方向上所做的任何努力（无论是在文献中还是在所谓的W3C sparql蕴含 机制中）都无法捕获UCQ和UCQs的某些答案。普通图上sparql的标准解释。我们将这些形式化为任何旨在调和某些答案的语义所要满足的要求，并且sparql答案，并将其扩展为三个附加要求。然后，我们使用select，union，join和optional定义两个满足sparql查询所有要求的语义。最后，我们研究了在这些语义下，在一个富含KG的KG上查询应答的组合复杂性。${\mathit{\text{DL-Lite}}}_{\mathcal{[R}}$本体，表明对于sparql的几个片段，在普通KG上用于查询应答的已知上限是匹配的。