Electronic commerce is emerging as a major application area for database systems. A large number of e-commerce sites provide electronic product catalogs that allow users to search products of interest. Due to the constant evolution and the high sparsity of e-commerce data, most commercial e-commerce systems use the so-called vertical schema for data storage. However, query processing for data s...

It is widely accepted practice to build domain models as a conceptual basis for software systems. Normally, the conceptual schema cannot be supplied by domain experts but is constructed by modelling experts. However, this is infeasible in many cases, e.g., if the system is to be generated ad hoc from a conceptual schema. This paper presents an iterative process that helps domain experts to crea...

In this paper we rst review the main results in the theory of schemata in Genetic Programming (GP) and summarise a new GP schema theory which is based on a new deenition of schema. Then we study the creation, propagation and disruption of this new form of schemata in real runs, for standard crossover, one-point crossover and selection only. Finally, we discuss these results in the light our GP ...

Sharing schemas is a shortcut to data interoperability, while in grid environments there are many difficulties such as schema disagreements and schema evolutions. We propose a new ”mappings first, schemas later” schema model, named Grid Schema. The Grid Schema uses the idea of context-free mapping to modularize schemas and its translation rules. This is incorporated into its schema validation m...

In this work, a new external schema definition methodology for object oriented databases (OODB) that solves some of the problems of existing methodologies is presented. In particular, this new methodology avoids the need for generating derived classes that are not directly used in the defined external schema. Also, it offers a way of integrating and reusing different external schema definitions.

In this paper we first review the main results in the theory of schemata in Genetic Programming (GP) and summarise a new GP schema theory which is based on a new definition of schema. Then we study the creation, propagation and disruption of this new form of schemata in real runs, for standard crossover, one-point crossover and selection only. Finally, we discuss these results in the light our ...

With the growing amount of semantic data published on the Web the problem of coreference resolution gains in importance. The linked data initiative provided guidelines for publishing RDF datasets and new datasets are constantly being made available. Such datasets often contain descriptions of the same real-world entities but use different URIs to refer to them. In order to utilize published dat...

XML Schema has emerged as a promising data model that unites structured and unstructured content. The Oracle database has led the commercial database community in integrating support for XML Schema inside an enterprise data server. The foundation for this was laid with the absorption of the SQL:1999 'objectrelational' type system in the database, which provided the necessary hierarchical abstra...

In this paper we analyze and discuss schema quality in the schema integration process. In doing so, we apply a framework for evaluating the quality of a conceptual schema (e.g. conceptual database schema). In our analysis we combine quality factors and quality metrics with the schema integration process, which is often described as having four distinct phases: pre-integration, comparison of the...