Ontology-based visual query formulation is a viable alternative to textual query editors in the Semantic Web domain for extracting data from structured data sources in terms of the skills and knowledge required. A visual query system is at any moment responsible for providing the user with query extension suggestions; however, suggestions leading to empty results are often not useful. To this end, in this article, we first present an approach for projecting OWL 2 ontologies into navigation graphs to be used for query formulation and then a solution where an efficient finite index is used to calculate non-ranked approximated extension suggestions for ontology-based visual query systems using navigation graphs. The results of our experiments suggest that one can efficiently project an ontology into a navigation graph, query it for running an interactive user interface, and suggest query extensions that do not lead to dead-ends.

中文翻译：

---

通过本体投影和索引对可视化查询系统的查询扩展建议

基于本体的可视化查询公式是语义 Web 领域中文本查询编辑器的可行替代方案，用于根据所需的技能和知识从结构化数据源中提取数据。可视化查询系统随时负责为用户提供查询扩展建议；然而，导致空结果的建议通常没有用。为此，在本文中，我们首先提出一种将 OWL 2 本体投影到用于查询公式的导航图中的方法，然后提出一种解决方案，其中使用有效的有限索引来计算基于本体的非排名近似扩展建议使用导航图的可视化查询系统。我们的实验结果表明，可以有效地将本体投影到导航图中，