Analyzing the Tagging Quality of the Spanish OpenStreetMap

In this paper, a framework for the assessment of the quality of OpenStreetMap is presented, comprising a batch of methods to analyze the quality of entity tagging. The approach uses Taginfo as a reference base and analyses quality measures such as completeness, compliance, consistence, granularity, richness and trust . The framework has been used to analyze the quality of OpenStreetMap in Spain, comparing the main cities of Spain. Also a comparison between Spain and some major European cities has been carried out. Additionally, a Web tool has been also developed in order to facilitate the same kind of analysis in any area of the world

Detecting and Diagnosing Syntactic and Semantic Errors in SPARQL Queries

ABSTRACT In this paper we present a tool to syntactically and semantically validate SPARQL queries. With this aim, we extract triple patterns and filter conditions from SPARQL queries and we use the OWL API and an OWL ontology reasoner in order to detect wrong expressions. Given an ontology and a query, the tool reports di↵erent kinds of programming errors: wrong use of vocabulary, wrong use of resources and literals, wrong filter conditions and wrong use of variables in triple patterns and filter conditions. When the OWL ontology reasoner is used the tool reports a diagnosis

Metamorphic testing of OpenStreetMap

Context: OpenStreetMap represents a collaborative effort of many different and unrelated users to create a free map of the world. Although contributors follow some general guidelines, unsupervised additions are prone to include erroneous information. Unfortunately, it is impossible to automatically detect most of these issues because there does not exist an oracle to evaluate whether the information is correct or not. Metamorphic testing has shown to be very useful in assessing the correctness of very heterogeneous artifacts when oracles are not available. Objective: The main goal of our work is to provide a (fully implemented) framework, based on metamorphic testing, that will support the analysis of the information provided in OpenStreetMap with the goal of detecting faulty information. Method: We defined a general metamorphic testing framework to deal with OpenStreetMap. We identified a set of good metamorphic relations. In order to have as much automation as possible, we paid special attention to the automatic selection of follow-up inputs because they are fundamental to diminish manual testing. In order to assess the usefulness of our framework, we applied it to analyze maps of four cities in different continents. The rationale is that we would be dealing with different problems created by different contributors. Results: We obtained experimental evidence that shows the potential value of our framework. The application of our framework to the analysis of the chosen cities revealed errors in all of them and in all the considered categories. Conclusion: The experiments showed the usefulness of our framework to identify potential issues in the information appearing in OpenStreetMap. Although our metamorphic relations are very helpful, future users of the framework might identify other relations to deal with specific situations not covered by our relations. Since we provide a general pattern to define metamorphic relations, it is relatively easy to extend the existing framework. In particular, since all our metamorphic relations are implemented and the code is freely available, users have a pattern to implement new relations

A Safe Relational Calculus for Functional Logic Deductive Databases1 1This work has been partially supported by the Spanish project of the Ministry of Science and Technology “INDALOG” TIC2002-03968.

AbstractIn this paper, we present an extended relational calculus for expressing queries in functional-logic deductive databases. This calculus is based on first-order logic and handles relation predicates, equalities and inequalities over partially defined terms, and approximation equations. For the calculus formulas, we have studied syntactic conditions in order to ensure the domain independence property. Finally, we have studied its equivalence w.r.t. the original query language, which is based on equality and inequality constraints

A Safe Calculus and Algebra for Querying Functional Logic Deductive Databases

In this paper, we present an extended relational calculus and algebra for a functional logic deductive database language. The extended relational calculus is based on the relational rst-order logic, by adding constraints in the form of equalities and disequalities over complex (partially de ned and possibly in nite) values and interpreted functions. In addition, we propose the notion of safety over calculus formulas in order to guarantee the property of domain independence. In the case of the extended relational algebra, we provide a generalization of the selection and projection operators in order to restructure complex values by means of constructors and destructors, interpreted functions and function inverses, as well as, to consider equality and disequality constraints. Finally, we will state that the two query formalisms (calculus and algebra) are equivalent