Author name cluster

Federico Ulliana

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4 papers

1 author row

IJCAI Conference 2019 Conference Paper

Oblivious and Semi-Oblivious Boundedness for Existential Rules

Pierre Bourhis
Michel Leclère
Marie-Laure Mugnier
Sophie Tison
Federico Ulliana
Lily Gallois

We study the notion of boundedness in the context positive existential rules, that is, wether there exists an upper bound to the depth of the chase procedure, that is independent from the initial instance. By focussing our attention on the oblivious and the semi-oblivious chase variants, we give a characterization of boundedness in terms of FO-rewritability and chase termination. We show that it is decidable to recognize if a set of rules is bounded for several classes of rules and outline the complexity of the problem.

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IJCAI Conference 2017 Conference Paper

Ontology-Mediated Query Answering for Key-Value Stores

Meghyn Bienvenu
Pierre Bourhis
Marie-Laure Mugnier
Sophie Tison
Federico Ulliana

We propose a novel rule-based ontology language for JSON records and investigate its computational properties. After providing a natural translation into first-order logic, we identify relationships to existing ontology languages, which yield decidability of query answering but only rough complexity bounds. By establishing an interesting and non-trivial connection to word rewriting, we are able to pinpoint the exact combined complexity of query answering in our framework and obtain tractability results for data complexity. The upper bounds are proven using a query reformulation technique, which can be implemented on top of key-value stores, thereby exploiting their querying facilities.

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AAAI Conference 2016 Conference Paper

Ontology-Mediated Queries for NOSQL Databases

Marie-Laure Mugnier
Marie-Christine Rousset
Federico Ulliana

Ontology-Based Data Access has been studied so far for relational structures and deployed on top of relational databases. This paradigm enables a uniform access to heterogeneous data sources, also coping with incomplete information. Whether OBDA is suitable also for non-relational structures, like those shared by increasingly popular NOSQL languages, is still an open question. In this paper, we study the problem of answering ontology-mediated queries on top of key-value stores. We formalize the data model and core queries of these systems, and introduce a rule language to express lightweight ontologies on top of data. We study the decidability and data complexity of query answering in this setting.

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AAAI Conference 2015 Conference Paper

Extracting Bounded-Level Modules from Deductive RDF Triplestores

Marie-Christine Rousset
Federico Ulliana

We present a novel semantics for extracting bounded-level modules from RDF ontologies and databases augmented with safe inference rules, à la Datalog. Dealing with a recursive rule language poses challenging issues for defining the module semantics, and also makes module extraction algorithmically unsolvable in some cases. Our results include a set of module extraction algorithms compliant with the novel semantics. Experimental results show that the resulting framework is effective in extracting expressive modules from RDF datasets with formal guarantees, whilst controlling their succinctness.

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