Web queries have been and will remain an essential tool for accessing, processing, and, ultimately, reasoning with data on the Web. With the vast data size on the Web and Semantic Web, reducing costs of data transfer and query evaluation for Web queries is crucial. To reduce costs, it is necessary to narrow the data candidates to query, simplify complex queries and reduce intermediate results. ...

Web queries have been and will remain an essential tool for accessing, processing, and, ultimately, reasoning with data on the Web. With the vast data size on the Web and Semantic Web, reducing costs of data transfer and query evaluation for Web queries is crucial. To reduce costs, it is necessary to narrow the data candidates to query, simplify complex queries and reduce intermediate results. ...

Default rules, i.e. statements of the form normally a’s are b’s, are usually handled in Answer Set Programming by means of negation as failure which provides a way to capture exceptions to normal situations. In this paper we propose another approach which offers an operational counterpart to negation as failure, and which may be thought as a corresponding dual attitude. The approach amounts to ...

Term rewriting has a large potential for industrial applications, but these applications are always larger than one could ever dream of: huge sets of rewrite rules and gigantic terms to rewrite pose interesting challenges for implementors and theoreti-cians alike. We give a brief overview of the generation of term-rewriting-based tools as done in the Asf+Sdf Meta-Environment and then we sketch ...

We generalise the recursive path ordering (rpo) in order to deal with alpha-equivalence classes of terms, using the nominal approach. We then use the nominal rpo to check termination, and to design a completion procedure, for nominal rewriting systems. Nominal rewriting generalises first-order rewriting by providing support for the specification of binding operators — alpha-equivalence is axiom...

We show that confluence of shallow and right-linear term rewriting systems is decidable. This class of rewriting system is expressive enough to include nontrivial nonground rules such as commutativity, identity, and idempotence. Our proof uses the fact that this class of rewrite systems is known to be regularity-preserving, which implies that its reachability and joinability problems are decida...

This article proposes a compositional semantics for term rewriting systems, i.e. a semantics preserving structuring operations such as the disjoint union. The semantics is based on the categorical construct of a monad, adapting the treatment of universal algebra in category theory to term rewriting systems. As an example, the preservation of connuence under the disjoint union of two term rewrit...

System S is a calculus providing the basic abstractions of term rewriting: matching and building terms, term traversal, combining computations and handling failure. The calculus forms a core language for implementation of a wide variety of rewriting languages, or more generally, languages for specifying tree transformations. In this paper we show how a conventional rewriting language based on c...

We investigate the rewrite relation over graphs induced by constructor-based weakly orthogonal graph rewriting systems. It is well known that this relation is not connuent in general whereas it is connuent in the case of weakly orthogonal term rewriting systems. We show, however , that the considered relation is always connuent, as well as connuent modulo bisimilarity, for a large class of grap...

Shuffle operads were introduced to forget the symmetric group actions on while preserving all possible operadic compositions. Rewriting methods then applied via shuffle operads: in particular, a notion of Gröbner basis was for with respect total order tree monomials. In this article, we introduce structure polygraphs as categorical model rewriting operads, which generalizes bases approach by re...