Abstract: It is difficult for entity search and question answering over text corpora to join cues from multiple documents to process relationship-centric search tasks, although structured querying over knowledge base can resolve such problem, but it still suffers from poor recall because of the heterogeneity and incompleteness of knowledge base. To address these problems, the knowledge graph was extended with information from textual corpora and a corresponding triple pattern with textual phrases was designed for uniform query of knowledge graph and textual corpora. Accordingly, a model for automatic query relaxation and scoring query answers (tuples of entities) was proposed, and an efficient top-k query processing strategy was put forward. Comparison experiments were conducted with two classical methods on three different benchmarks including entity search, entity-relationship search and complex entity-relationship queries using a combination of the Yago knowledge graph and the entity-annotated ClueWeb '09 corpus. The experimental results show that the entity-relationship search system with query relaxation over extended knowledge base outperforms the comparison systems with a big margin, the Mean Average Precision (MAP) are improved by more than 27%, 37%, 64% respectively on the three benchmarks.

Key words: knowledge graph, entity-relationship query, entity search, triple pattern query, query relaxation

摘要： 现有文本数据集上的实体搜索和自然语言查询方法无法处理需要将分散在不同文档中的信息碎片链接起来以满足有复杂实体关系的查询,而知识库上的查询虽然可以表示实体间的复杂关系,但由于知识库的异构性和不完全性,通常查全率较低。针对这些问题,提出使用文本数据集对知识库进行扩展,并设计相应的含文本短语的三元组模式查询以支持对知识库和文本数据的统一查询。在此基础上,设计并实现了查询放松机制和对结果元组的评分模型,并给出了高效的查询处理方法。使用YAGO、ClueWeb09和其上的FACC1数据集,在三个不同的查询测试集(实体检索、实体关系检索和复杂的实体关系查询)上与两个典型相关工作作了比较。实验结果显示,扩展知识图谱上使用查询放松规则的实体关系检索系统的检索效果大大超出了其他系统,具体地在三个查询测试集上,其平均正确率均值(MAP)比其他系统分别提升了27%、37%和64%以上。

关键词: 知识图谱, 实体关系检索, 实体搜索, 三元组模式查询, 查询放松