LitCQD: Multi-Hop Reasoning in Incomplete Knowledge Graphs with Numeric Literals

Caglar Demir, Michel Wiebesiek, Renzhong Lu, Axel-Cyrille Ngonga Ngomo, Stefan Heindorf

Abstract:

Most real-world knowledge graphs, including Wikidata,
DBpedia, and Yago are incomplete. Answering queries on such incomplete
graphs is an important, but challenging problem. Recently, a number
of approaches, including complex query decomposition (CQD), have
been proposed to answer complex, multi-hop queries with conjunctions
and disjunctions on such graphs. However, these approaches only consider
graphs consisting of entities and relations, neglecting literal values.
In this paper, we propose LitCQD—an approach to answer complex,
multi-hop queries where both the query and the knowledge graph can
contain numeric literal values: LitCQD can answer queries having numerical
answers or having entity answers satisfying numerical constraints.
For example, it allows to query (1) persons living in New York having a
certain age, and (2) the average age of persons living in New York. We
evaluate LitCQD on query types with and without literal values. To evaluate
LitCQD, we generate complex, multi-hop queries and their expected
answers on a version of the FB15k-237 dataset that was extended by literal
values.