This project continues the collaboration between FBK and TUW about defeasible knowledge in description logics in the Contextualized Knowledge Repository (CKR) framework.

In applications, knowledge can hold by default and be overridden in more specific contexts. For example, in a tourism event recommendation system, events can appear as suggested to a class of tourists in a general context: in the more specific context of a particular tourist, preferences can be refined to more precise interests, which may override those at higher contexts.

Goal of this project is to enhance the answer set programming (ASP) based realization of CKR to deal with complex context hierarchies: we use an ASP extension recently proposed by TUW, ASP with algebraic measures, which allows for reasoning on orderings induced by the organization of defeasible knowledge. This collaboration will provide a prototype for reasoning over CKR hierarchies, but also an application for ASP with algebraic measures.


Prototype implementation: realization of reasoning service for query answering over CKR with contextual hierarchies. The prototype will be made available in AI4EU platform.

Report on formalization: technical report and paper submission containing the defining the formal aspects of model selection for contextual hierarchies via ASP with Algebraic Measures and some initial evaluations in the prototype.


Project Partners:

  • Fondazione Bruno Kessler (FBK), Loris Bozzato
  • TU Wien, Thomas EIter

Primary Contact: Loris Bozzato, FBK

Main results of micro project:

The goal of this project is to reason on complex contextualized knowledge bases using an answer set programming extension with algebraic measures and show the capabilities of this formalism.

The main formal contributions of this project are:
– an extension of the CKR contextual framework to reason about defeasible information over multi-relational contextual hierarchies.
– an ASP based modelling of multi-relational CKRs, where combination of model preferences is realized via algebraic measure expressions.
– an asprin based implementation of query answering in a fragment of multi-relational CKRs, extending the existing CKR datalog translation.
– a study of further capabilities of algebraic measures, showing the possibilities for reasoning on model aggregation.

Contribution to the objectives of HumaneAI-net WPs

The results of the MP are relevant for AI as they show a combination of non-monotonic contextualized DLs in the CKR framework and Logic Programming with numerical measures in weighted LARS.

With respect to the HumaneAI vision, the resulting framework provides a tool for representing, e.g., complex social structures and the contextualization of information relative to such social organizations. With respect to the WP1 objectives, the work combines different AI areas, and follows the direction of joining symbolic and numeric knowledge representation and reasoning methods with notions of uncertainty.

Tangible outputs