Section: New Results

Link keys

Link keys (§3.3) are explored following two directions:

• Extracting link keys;

• Reasoning with link keys.

Link key extraction with relational concept analysis

Participants : Manuel Atencia, Jérôme David [Correspondent] , Jérôme Euzenat, Jérémy Vizzini.

A first method has been designed to extract and select link keys from two classes which deals with multiple values but not object values [1]. Moreover, the extraction step has been rephrased in formal concept analysis (FCA) allowing to generate link keys across relational tables [2].

We have extended this latter work so that it can deal with multiple object values when the data set is cycle free. This encoding does not necessarily generate the optimal link keys. Hence, we use relational concept analysis (RCA), an extension of FCA taking relations between concepts into account. We show that a new expression of this problem is able to extract the optimal link keys even in the presence of cyclic dependencies. Moreover, the proposed process does not require information about the alignments of the ontologies to find out from which pairs of classes to extract link keys.

We implemented these methods and evaluated them by reproducing the experiments made in previous studies [14]. This shows that the method extracts the expected results as well as (also expected) scalability issues.

Tableau method for $\mathrm{𝒜ℒ𝒞}+$Link key reasoning

Participants : Manuel Atencia [Correspondent] , Jérôme David, Jérôme Euzenat.

Link keys can also be thought of as axioms in a description logic. As such, they can contribute to infer ABox axioms, such as links, or terminological axioms, and other link keys. We have extended the tableau method designed for the $\mathrm{𝒜ℒ𝒞}$ description logic to support reasoning with link keys in $\mathrm{𝒜ℒ𝒞}$ [5]. This year, we have proven that this method is sound, complete and that it always terminates.