1,720,974 research outputs found
Data model descriptions and translation signatures in a multi-model framework
No full textWe refer to the problem of translating schemas from a data model to another, in a multi-model framework. Specifically, we consider an approach where translations are specified as Datalog-like programs. In this context we show how it is possible to reason on models and schemas involved as input and output for a translation. The various notions are formalized: (i) concise descriptions of models in terms of sets of constructs, with associated propositional formulas; (ii) a notion of signature for translation rules (with the property that signatures can be automatically computed out of rules); (iii) the application of signatures to models. The main result is that the target model of a translation can be completely characterized given the description of the source model and the signatures of the rules. This result is being exploited in the framework of a tool that implements model generic translations, as the basis for the automatic generation of translations out of a library of elementary ones
A Linear and Monotonic Strategy to Keyword Search over RDF Data
No full textKeyword-based search over (semi)structured data is today considered an essential feature of modern information management systems and has become an hot topic in database research and development. Most of the recent approaches to this problem refer to a general scenario where: (i) the data source is represented as a graph, (ii) answers to queries are sub-graphs of the source containing keywords from queries, and (iii) solutions are ranked according to a relevance criteria. In this paper, we illustrate a novel approach to keyword search over semantic data that combines a solution building algorithm and a ranking technique to generate the best results in the first answers generated. We show that our approach is monotonic and has a linear computational complexity, greatly reducing the complexity of the overall process. Finally, experiments demonstrate that our approach exhibits very good efficiency and effectiveness, especially with respect to competing approaches
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