图 书 馆
带有空白节点的SPARQL的某些答案Certain Answers for SPARQL with Blank Nodes |
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| 课程网址: | http://videolectures.net/iswc2018_hernandez_certain_sparql_nodes/ |
| 主讲教师: | Daniel Hernández |
| 开课单位: | 智利大学 |
| 开课时间: | 2018-11-22 |
| 课程语种: | 英语 |
| 中文简介: |  |
| 课程简介: | Blank nodes in RDF graphs can be used to represent existential values known to exist but whose identity remains unknown. A prominent example of such usage can be found in the Wikidata dataset where, e.g., the author of Beowulf is given as a blank node. However, while SPARQL considers blank nodes in a query as existentials, it treats blank nodes in data more like constants. Running SPARQL queries over datasets with unknown values thus may lead to uncertain results, which may make the SPARQL semantics unsuitable for datasets with existential blank nodes. We thus explore the feasibility of an alternative SPARQL semantics based on certain answers. In order to estimate the performance costs that would be associated with such a change in semantics for current implementations, we adapt and evaluate approximation techniques proposed in a relational database setting for a core fragment of SPARQL. To further understand the impact that such a change in semantics may have on query solutions, we analyse how such a change would affect the results of user queries over Wikidata. |
| 关 键 词: | Wikidata数据集中; SPARQL语义; Wikidata的查询结果; SPARQL核心片段 |
| 课程来源: | 视频讲座网 |
| 数据采集: | 2023-01-16：cyh |
| 最后编审: | 2023-01-16：cyh |
| 阅读次数: | 30 |