Abstract The publication of Linked Open Data on the Web has gained tremendous
momentum over the last five years. This development makes possible (and interesting) the …

In today's databases, previous query answers rarely benefit answering future queries. For
the first time, to the best of our knowledge, we change this paradigm in an approximate …

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 …

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 …

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 …

Recent years have witnessed the development of large knowledge bases (KBs). Due to the
lack of information about the content and schema semantics of KBs, users are often not able …

Query relaxation has been studied as a way to find approximate answers when user queries
are too specific or do not align well with the data schema. We are here interested in the …

Semantic metadata standards pave the way for interoperability by providing building
operators and application developers with common schemes to describe building resources …

Query relaxation has been proposed to cope with the problem of queries that produce none
or insufficient answers. The goal is to modify these queries to be able to produce alternative …