Abstract Sparklis is a Semantic Web tool that helps users explore and query SPARQL
endpoints by guiding them in the interactive building of questions and answers, from simple …

The LOD cloud offers a plethora of RDF data sources where users discover items of interest
by issuing SPARQL queries. A common query problem for users is to face with empty …

Entity-relationship-structured data is becoming more important on the Web. For example,
large knowledge bases have been automatically constructed by information extraction from …

In this paper, we argue that query relaxation over RDF data is an important but largely
overlooked research topic: the Semantic Web standards allow for answering crisp queries …

Abstract Knowledge graphs and other forms of relational data have become a widespread
kind of data, and powerful methods to analyze and learn from them are needed. Formal …

Recent advances in Web-information extraction have led to the creation of several large
Knowledge Bases (KBs). Querying these KBs often results in empty answers that do not …

Research in cooperative query answering is triggered by the observation that users are
often not able to correctly formulate queries to databases such that they return the intended …

This paper addresses the problem of failing RDF queries. Query relaxation is one of the
cooperative techniques that allows providing users with alternative answers instead of an …

Flexible querying techniques can enhance users' access to complex, heterogeneous
datasets in settings such as Linked Data, where the user may not always know how a query …

We develop query relaxation techniques for regular path queries and combine them with
query approximation in order to support flexible querying of RDF data when the user lacks …