Modeling and Querying Evidential Databases

Abstract : The theory of belief functions (a.k.a, the Evidence Theory) offers powerful tools to mode! and handle imperfect pieces of information. Thus, it provides an adequate framework able to represent conjointly uncertainty, imprecision and ignorance. In this context, data are stored in a specific database model called evidential databases. An evidential database includes two levels of uncertainty: (i) the attribute level uncertainty expressed via some degrees of truthfulness about the hypotheses in attributes; (ii) the tuple level uncertainty expressed through an interval of confidence about the existenceof the tuple in the table. An evidential database itself can be modeled in two forms:(i) the compact form represented as a set of attributes and a set of tuples; (ii) the possible worlds' form represented as a set of candidate databases where each candidate is a possible representation of the imperfect compact database. Querying the possible worlds' form is a fundamental step in order to check the querying methods over the compact one. In fact, a model is said to be a strong representation system when results of querying its compact form are equivalent to results of querying its non compact form.This thesis focuses on foundations of evidential databases in both modeling and querying. The main contributions are summarized as follows:(i) Modeling and querying the compact evidential database (EDB): We implement the compact evidential database (EDB) using the object-relational design which allows to introduce the querying of the database model under relational operators. We also propose the formalism, the algorithms and the experiments of other typesof queries: the evidential top-k and the evidential skyline that we apply over a real dataset extracted from TripAdvisor.(ii) Modeling the possible worlds' form of (EDB): We model the possible worlds' form of the evidential database (EDB) by treating both levels of uncertainty (the tuple leve! and the attribute level).(iii) Modeling and querying the evidential conditional database (ECD): After provingt hat the evidential database (EDB) is not a strong representation system, we develop a new evidential conditional database model named (ECD). Thus, we present the formalism of querying the compact and the possible worlds' forms of the (ECD) to evaluate the querying methods under relational operators. Finally, we discuss the results of these querying methods and the specificities of the (ECD)model.
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Fatma Ezzahra Bousnina. Modeling and Querying Evidential Databases. Other [cs.OH]. ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers; Université de Tunis, 2019. English. ⟨NNT : 2019ESMA0007⟩. ⟨tel-02162105⟩

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