Semantic Web systems provide open interfaces for end-users to access data via a powerful
high-level query language, SPARQL. But users unfamiliar with either the details of SPARQL …

Reverse engineering problems for conjunctive queries (CQs), such as query by example
(QBE) or definability, take a set of user examples and convert them into an explanatory CQ …

We investigate the problem of learning graph queries by exploiting user examples. The input
consists of a graph database in which the user has labeled a few nodes as positive or …

The product homomorphism problem (PHP) takes as input a finite collection of structures
A_1,..., A_n and a structure B, and asks if there is a homomorphism from the direct product …

Given an input dataset (ie, a set of tuples), query definability in Ontology-based Data
Management (OBDM) amounts to finding a query over the ontology whose certain answers …

Similarities play a pivotal role in diverse real-world scenarios, driving extensive research
into methodologies for measuring entity similarity and expanding sets of entities with similar …

Reverse engineering queries from given data, as in the case of query-by-example and query
definability, is an important problem with many applications that has recently gained …

With the emergence of machine learning (ML) techniques in database research, ML has
already proved a tremendous potential to dramatically impact the foundations, algorithms …

We study the definability problem for first-order logic, denoted by FO-Def. The input of FO-
Def is a relational database instance I and a relation R; the question to answer is whether …

Similarities between entities occur frequently in many real-world scenarios. For over a
century, researchers in different fields have proposed a range of approaches to measure the …