Resumen: Purpose: There is an increasing interest in the use of knowledge graphs to represent real-world knowledge and a common need to manage imprecise knowledge in many real-world applications. This paper aims to study approaches to solve flexible queries over knowledge graphs. Design/methodology/approach: By introducing fuzzy logic in the query answering process, the authors are able to obtain a novel algorithm to solve flexible queries over knowledge graphs. This approach is implemented in the FUzzy Knowledge Graphs system, a software tool with an intuitive user-graphical interface. Findings: This approach makes it possible to reuse semantic web standards (RDF, SPARQL and OWL 2) and builds a fuzzy layer on top of them. The application to a use case shows that the system can aggregate information in different ways by selecting different fusion operators and adapting to different user needs. Originality/value: This approach is more general than similar previous works in the literature and provides a specific way to represent the flexible restrictions (using fuzzy OWL 2 datatypes). Idioma: Inglés DOI: 10.1108/EL-02-2023-0052 Año: 2023 Publicado en: Electronic library 42, 3 (2023), 368-392 ISSN: 0264-0473 Factor impacto JCR: 1.5 (2023) Categ. JCR: INFORMATION SCIENCE & LIBRARY SCIENCE rank: 70 / 161 = 0.435 (2023) - Q2 - T2 Factor impacto CITESCORE: 4.2 - Library and Information Sciences (Q1) - Computer Science Applications (Q2)