We propose a reformulation algorithm as well as a set of re-formulation rules for models of constraint satisfaction problems written in our high-level constraint programming language esra, which is more expressive than opl and is compiled into opl. For the class of mapping problems, the reformulation algorithm achieves models that integrate a constraint programming formulation and an integer pr...

Specification by reformulation is a general interface paradigm. It is an abstraction of retrieval by reformulation, a paradigm used in previous systems for assisting users in formulating database queries. Specification by reformulation serves as a general foundation upon which domain specific applications can be built. To illustrate its usage, we describe three services built within it: a datab...

We are concerned with the compatible gauge reformulation for H(div) equations and the design of fast solvers of the resulting linear algebraic systems as in [5]. We propose an algebraic reformulation of the discrete H(div) equations along with an algebraic multigrid (AMG) technique for the reformulated problem. The reformulation uses discrete Hodge decompositions on co-chains to replace the dis...

Reformulation of a problem is intended to make the problem more amenable to efficient solution. This is equally true in the special case of reformulating a planning problem. This paper considers various ways in which reformulation can be exploited in planning.

In this paper we survey recent work on the perspective reformulation approach that generates tight, tractable relaxations for convex mixed integer nonlinear programs (MINLP)s. This preprocessing technique is applicable to cases where the MINLP contains binary indicator variables that force continuous decision variables to take the value 0, or to belong to a convex set. We derive from first prin...

We claim in this paper that “context” is a key design concept for stimulating people’s mind to discover new interpretations and understandings in the digital archive. Our approach to the notion of context is unique in terms of the proposal of the model of context from the viewpoint of database systems and informatics. We assume that content is actually comprised by two basic elements, namely co...

We discuss the hierarchies of linear and semidefinite programs defined by Lovász and Schrijver [33]. We describe recent progress on these hierarchies in the contexts of algorithm design, computational complexity and proof complexity.

We are concerned with the compatible gauge reformulation for H(div) equations and the design of fast solvers of the resulting linear algebraic systems as in [5]. We propose an algebraic reformulation of the discrete H(div) equations along with an algebraic multigrid (AMG) technique for the reformulated problem. The reformulation uses discrete Hodge decompositions on co-chains to replace the dis...

This paper proposes an approximate query reformulation framework for integrating heterogeneous ontologies. In order to achieve semantic interoperability in the Semantic Web, multiple ontologies have to be integrated. Ontology integration requires approximation mechanisms, since often no perfectly corresponding ontologies exist. However, most previous research efforts on ontology integration hav...

Ontology-based data access is an approach to organizing access to a database augmented with a logical theory. In this approach query answering proceeds through a reformulation of a given query into a new one which can be answered without any use of theory. Thus the problem reduces to the standard database setting. However, the size of the query may increase substantially during the reformulatio...