Graph databases have gained renewed interest in the last years, due to its applications in
areas such as the Semantic Web and Social Networks Analysis. We study the problem of …

Query languages for graph databases started to be investigated some 25 years ago. With
much current data, such as linked data on the Web and social network data, being graph …

It is a folk result in database theory that SQL cannot express recursive queries such as
reachability; in fact, a new construct was added to SQL3 to overcome this limitation …

Theoretical foundations for querying databases based on bags are studied in this paper. We
fully determine the strength of many polynomial-time bag operators relative to an ambient …

We study adding aggregate operators, such as summing up elements of a column of a
relation, to logics with counting mechanisms. The primary motivation comes from database …

We present Datalog LITE, a new deductive query language with a linear-time model-
checking algorithm, that is, linear time data complexity and program complexity. Datalog …

be from any type of computer printer. Page 1 INFORMATION TO USERS This manuscript has
been reproduced from the microfilm master. UMI films the text directly from the original or copy …

In this paper, we propose an extension of the well-founded and stable model semantics for
logic programs with aggregates. Our approach uses Approximation Theory, a fixpoint theory …

We study the expressive power of the LARA language--a recently proposed unified model
for expressing relational and linear algebra operations--both in terms of traditional database …

It is a folk result in database theory that SQL cannot express recursive queries such as
reachability; in fact, a new construct was added to SQL3 to overcome this limitation …