D1.2 , Review of methods and systems from computational logic
Short Description:
This report is devoted to give a review of methods and systems from
computational logic and to point out the applicability of them to
data integration tasks. In particular, since our goal is to integrate
computational logic systems in a data integration framework, in this
report, we focus on computational logic systems which can be seen as
extensions of Database Systems. In particular, we first focus on
deductive database systems which, essentially, extend relational
database systems by recursion and stratified negation. Then, we
analyze the more recent answer set programming systems which go
beyond deductive databases, supporting also unstratified negation and
other advanced constructs like disjunction, and various forms of
constraints. These systems are based on a bottom-up computational
model which is closer to the computational model of database systems
than the top-down (proof theoretic) computational model, and it is
better suited for dealing with larger amounts of data. The above
class of computational logic systems (including both deductive
database systems and answer set programming systems) is often
referred to as the class of declarative computational logic
systems, since these systems support a fully declarative programming
style (while in Prolog the result depends on the ordering of the
rules in the program, and also on the ordering of the goals in the
bodies of the rules).