TINTIN : comprobación incremental de aserciones SQL

Ninguno de los SGBD más populares del momento implementa aserciones SQL, obligando así a implementar manualmente su comprobación. Por ello, presentamos TINTIN: una aplicación que genera automáticamente el código SQL para comprobar aserciones. Dicho código captura las tuplas insertadas/borradas en una transacción, comprueba que ninguna de ellas viole ninguna aserción mediante consultas SQL, y materializa los cambios en caso que sean satisfechas. La eficiencia del código se basa en la comprobación incremental de las aserciones.Peer ReviewedPostprint (published version

GROM: a general rewriter of semantic mappings

We present GROM, a tool conceived to handle high-level schema mappings between semantic descriptions of a source and a target database. GROM rewrites mappings between the virtual, view-based semantic schemas, in terms of mappings between the two physical databases, and then executes them. The system serves the purpose of teaching two main lessons. First, designing mappings among higher-level descriptions is often simpler than working with the original schemas. Second, as soon as the view-definition language becomes more expressive, to handle, for example, negation, the mapping problem becomes extremely challenging from the technical viewpoint, so that one needs to find a proper trade-off between expressiveness and scalability.Peer ReviewedPostprint (published version

The HumanoidLab: Involving students in a research centre through an educational initiative

Trabajo presentado a la 6th International Conference on Compute Supported Education, celebrada en Barcelona del 1 al 3 de abril de 2014.The HumanoidLab is a more than 5 year old activity aimed to use educational robots to approach students to our Research Centre. Different commercial educative humanoid platforms have been used to introduce students to different aspects of robotics using projects and offering guidance and assistance. About 40 students have performed small mechanics, electronics or programming projects that are used to improve the robots by adding features. Robotics competitions are used as a motivation tool. A two weeks course was started that has received 80 undergraduate students, and more than 100 secondary school students in a short version. The experience has been very positive for students and for the institution: some of these students have performed their scholar projects and research in robotics and continue enrolled in the robotics field, and some of them are currently in research groups at IRI.The HumanoidLab has been mainly funded by a program of the Polytechnic University of Catalonia devoted to strength department activities with 20KEur.Peer Reviewe

Testing Termination of Query Satisfiability Checking on Expressive Database Schemas

A query is satisfiable if there is at least one consistent instance of the database in which it has a non-empty answer. Defining queries on a database schema and checking their satisfiability can help the database designer to be sure whether the produced database schema is what was intended. The formulation of such queries may easily require the use of some arithmetic comparisons or negated expressions. Unfortunately, checking the satisfiability of this class of queries on a database schema that most likely have some integrity constraints (e.g., keys, foreign keys, Boolean checks) is, in general, undecidable. However, although the problem is undecidable for such a class of schemas and queries, it may not be so for a particular query satisfiability check. In this paper, we propose to perform a termination test as a previous step to query satisfiability checking. If positive, the termination test guarantees that the corresponding query satisfiability check will terminate. We assume the CQC method is the underlying query satisfiability checking method; to the best of our knowledge, it is the only method of this kind able to deal with schemas and queries as expressive as the ones we consider.Preprin

A schema-only approach to validate XML schema mappings

Since the emergence of the Web, the ability to map XML data between different data sources has become crucial. Defining a mapping is however not a fully automatic process. The designer needs to figure out whether the mapping is what was intended. Our approach to this validation consists of defining and checking certain desirable properties of mappings. We translate the XML schemas and the mapping into first-order logic formalism and apply a reasoning mechanism to check the desirable properties automatically, without assuming any particular instantiation of the schemas.Preprin

Validation of schema mappings with nested queries

With the emergence of the Web and the wide use of XML for representing data, the ability to map not only flat relational but also nested data has become crucial. The design of schema mappings is a semi-automatic process. A human designer is needed to guide the process, choose among mapping candidates, and successively refine the mapping. The designer needs a way to figure out whether the mapping is what was intended. Our approach to mapping validation allows the designer to check whether the mapping satisfies certain desirable properties. In this paper, we focus on the validation of mappings between nested relational schemas, in which the mapping assertions are either inclusions or equalities of nested queries. We focus on the nested relational setting since most XML’s Document Type Definitions (DTDs) can be represented in this model. We perform the validation by reasoning on the schemas and mapping definition. We take into account the integrity constraints defined on both the source and target schema.Preprin

Ontology-based data integration in EPNet: Production and distribution of food during the Roman Empire

Semantic technologies are rapidly changing the historical research. Over the last decades, an immense amount of new quantifiable data have been accumulated, and made available in interchangeable formats, in social sciences and humanities, opening up new possibilities for solving old questions and posing new ones. This paper introduces a framework that eases the access of scholars to historical and cultural data about food production and commercial trade system during the Roman Empire, distributed across different data sources. The proposed approach relies on the Ontology-Based Data Access (OBDA) paradigm, where the different datasets are virtually integrated by a conceptual layer (an ontology) that provides to the user a clear point of access and a unified and unambiguous conceptual view

Characterization of coastal upwelling events during the generation of the water column stratification in spring (Vilanova i la Geltrú, NW Mediterranean)

This article presents some preliminary results on the characterization of inputs of offshore waters (upwelling events) in the coast off Vilanova i la Geltrú (NW Mediterranean) in the spring of the years 2010, 2012 and 2014. The upwelling events are studied in terms of meteorological and oceanographic conditionsPostprint (author’s final draft

TINTIN: a Tool for INcremental INTegrity checking of Assertions in SQL Server

We present TINTIN, a tool to perform efficient integrity checking of SQL assertions in SQL Server. TINTIN rewrites each assertion into a set of standard SQL queries that, given a set of insertions and deletions of tuples, allow to incrementally compute whether this update violates the assertion or not. If one of such queries returns a non empty answer, then the assertion is violated. Efficiency is achieved by evaluating only those data and those assertions that can actually be violated according to the update. TINTIN is aimed at two different purposes. First, to show the feasibility of our approach by implementing it on a commercial relational DBMS. Second, to illustrate that the efficiency we achieve is good enough for making assertions to be used in practice.Peer ReviewedPostprint (published version

AuRUS: explaining the validation of UML/OCL conceptual schemas

The validation and the verification of conceptual schemas have attracted a lot of interest during the last years, and several tools have been developed to automate this process as much as possible. This is achieved, in general, by assessing whether the schema satisfies different kinds of desirable properties which ensure that the schema is correct. In this paper we describe AuRUS, a tool we have developed to analyze UML/OCL conceptual schemas and to explain their (in)correctness. When a property is satisfied, AuRUS provides a sample instantiation of the schema showing a particular situation where the property holds. When it is not, AuRUS provides an explanation for such unsatisfiability, i.e., a set of integrity constraints which is in contradiction with the property.Peer ReviewedPostprint (author’s final draft