Program

WASPIQ 2017
Workshop on ASP technologIes for Querying large scale multisource heterogeneous web information 2017
http://waspiq2017.lsis.org

Tuesday june 27th 2017
Université d'Artois. 9, rue du temple. Arras
http://www.univ-artois.fr/L-universite/Informations-generales/Venir-a-l-...

PROGRAM

13:15-13:45 Odile Papini
A guided tour of the ASPIQ project

13:45-14:30 Ivan Vrzinczak
Foundations and Challenges of Reasoning Defeasibly over DL Ontologies

14:30-15:00 Pierre Drap, Laurent Garcia, Fabien Garreau, Claire Lefèvre, Odile Papini, Igor Stéphan, Eric Würbel
ASP Query answering: Application to underwater archaeological surveys querying

15:00-15:30 Laurent Garcia, Fabien Garreau, Claire Lefèvre, Odile Papini, Igor Stéphan, Eric Würbel
A Semantic characterization for ASP base revision

15:30-16:00 Jean-François Baget
Computing repairs (and more) with Answer Set Programming

16:00-16:30 Coffee break

16:30-17:00 Zied Bouraoui, Salem Benferhat, Sylvain Lagrue and Karim Tabia
Ontological Query answering under Uncertainty and/or Inconsistency

17:00-17:45 Andrea Tettamanzi
Possibilistic Test of OWL Axioms under the Open-World Assumption

DETAILED PROGRAM

13:15-13:45 Odile Papini
A guided tour of the ASPIQ project

Abstract:
The ASPIQ (ASP technologIes for Querying large scale multisource heterogeneous web information) project is a fundamental research project supported by the French National Research Agency (ANR) (http://aspiq.lsis.org). The overall objective of the project is reminded and the results of the project are presented, in particular new solutions for querying large scale multisource information.

13:45-14:30 Ivan Vrzinczak
Foundations and Challenges of Reasoning Defeasibly over DL Ontologies

Abstract:
Description Logics (DLs) are a family of logic-based knowledge representation formalisms with appealing computational properties and a variety of applications at the confluence of modern artificial intelligence and other areas. In particular, DLs are well-suited for representing and reasoning about ontologies and therefore constitute the formal foundations of the Semantic Web. The different DL formalisms that have been proposed in the literature provide us with a wide choice of constructors in the object language. However, these are intended to represent only classical, unquestionable knowledge, and are therefore unable to express the different aspects of uncertainty and vagueness that often show up in everyday life. Examples of these comprise the various guises of exceptions, typicality (and atypicality), approximations and many others, as usually encountered in the different forms of human quotidian reasoning. A similar argument can be put forward when moving to the level of entailment, that of the sanctioned conclusions from a knowledge base. DL systems provide for a variety of (standard and non-standard) reasoning services, but the underlying notion of entailment remains classical and therefore, depending on the application one has in mind, DLs inherit most of the criticisms raised in the development of the so-called non-classical logics. In this regard, endowing DLs and their associated reasoning services with the ability to cope with defeasibility is a natural step in their development. Indeed, the past two decades have witnessed the surge of many attempts to introduce non-monotonic reasoning capabilities in a DL setting. These range from preferential approaches to circumscription-based ones, amongst others. In spite of all the progress that has been achieved in the area, the study of non-monotonic reasoning in DLs remains a large avenue for exploration. To witness, the bulk of the effort in this direction has been put in the definition of accounts of defeasible subsumption and in the characterisation of appropriate notions of defeasible entailment relations. This suggests that existing approaches to reasoning with defeasible inheritance and typicality in ontologies may lack constructors that are important from a modelling perspective. Indeed, here we make a case for a number of additional defeasible constructs at the object level enriching the basic DL concept language and propose a corresponding preferential semantics. We show that this does not negatively impact decidability or complexity of reasoning for an important class of DLs, and that existing notions of preferential reasoning can be expressed in terms of our new constructs.

14:30-15:00 Pierre Drap, Laurent Garcia, Fabien Garreau, Claire Lefèvre, Odile Papini, Igor Stéphan, Eric Würbel
ASP Query answering: Application to underwater archaeological surveys querying

Abstract:
We focus on query answering of OWL2-QL knowledge base encoded with the extended $\exists$ASP formalism. We first propose an approach for query answering a knowledge base within the framework of ASP, we then compare the obtained results with the ones obtained querying the initial OWL2-QL knowledge base using SparQL and SQWRL languages. This comparison shows that using the ASP framework is not more costly than using the standard SparQL and SQWRL languages. Moreover, performing queries on both the ontological knowledge base and its JAVA representation allows one to visualize the answers and to construct a 3D density map which is useful for archaeologists. Indeed, 3D density maps could be the starting point to investigate spatial reasoning for archaeological sites. In a future work we plan to query ontology-based knowledge bases equipped with default rules, like in the ones used in medieval archaeological surveys of buildings in order to highlight the advantage of using the ASP framework.

15:00-15:30 Laurent Garcia, Fabien Garreau, Claire Lefèvre, Odile Papini, Igor Stéphan, Eric Würbel
A Semantic characterization for ASP base revision

Abstract:
The paper deals with base revision for Answer Set Programming
(ASP). Base revision in classical logic stems from the removal of formulas.
Exploiting the non-monotonicity of ASP allows one to propose other revision
strategies, namely addition strategy or removal and$\slash$or addition strategy. These strategies allow one to define families of rule-based revision operators.

15:30-16:00 Jean-François Baget
Computing repairs (and more) with Answer Set Programming

Abstract:
We consider a knowledge base built from a database D and an ontology O that contains existential rules and constraints. When (D, O) is unsatisfiable, the notion of repair is often used to extract a maximal subset R of D such that (R, O) is satisfiable. Slight variations of this definition allow, for instance, to compute a repair of the ground closure of D. In this presentation, we present a transformation of (D, O) to an ASP (answer set programming) program P such that R is a repair of (D, O) iff there is an answer set A of P that corresponds to R (more specifically, the subset of atoms of A using the original vocabulary is exactly R). This transformation is generic : With slight modifications, it allows to handle different versions of repairs, and we show that it can also be used to handle, for instance, some preferences that could be expressed on the atoms that should belong to a repair.

16:00-16:30 Coffee break

16:30-17:00 Zied Bouraoui, Salem Benferhat, Sylvain Lagrue and Karim Tabia
Ontological Query answering under Uncertainty and/or Inconsistency

Abstract:
Recent years have witnessed an increasing interest in Ontology-Based Data Access, in which structured knowledge (i.e. ontological knowledge) is exploited when querying. In this setting, the ontology is often assumed to be verified and validated while the data, which are typically provided in large quantities by various and unreliable sources, may be inconsistent with respect to the ontology. In the presence of inconsistency, the standard query answering process becomes no longer appropriate. In this talk, we overview a number of approaches for ontology-based query answering under uncertainty and/or inconsistency with a focus on the case where the data are given with priorities.

17:00-17:45 Andrea Tettamanzi
Possibilistic Test of OWL Axioms under the Open-World Assumption

Abstract:
I talk will present a theoretical framework, based on possibility theory, for
OWL candidate axiom testing against the evidence provided by knowledge
bases for which the open-world assumption holds. After revieweing the
basic intuitions behind it, its epistemological justifications, and its
main results, I will briefly illustrate its practical application to the
test of SubClassOf axioms against the DBpedia RDF dataset.