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Developed by Steffen Stadtm├╝ller
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Last Update 4 March 2009
Current Version [[current version:= <ask format="template" template="CurrentVersion" limit="1" searchlabel="" sort="version number" order="descending" default="no version available"> 1.x/ParOWL *</ask>]]
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NTKVersion 1.2.3

A component to transform inconsistant into consistant knowledge bases


Functional Description

The Inconsistency Handler provides a way to deal with inconsistent and incoherent knowledge bases in OWL. This is done by considering inconsistent ontologies to be based on a four-valued logic. These ontologies are translated to new consistent and coherent ontologies, in a way that classical two-valued reasoning tasks with the translated ontologies result in the same conclusions as paraconsistent four-valued reasoning.

The user can decide, whether he wants to translate all inconsistent ontologies automatically or select the ontologies, that should be translated. To provide a flexible way to define the new ontologies, three different ways to translate the inclusions in the knowledge base are possible:

  • Strong: Respects the deduction theorem and contraposition reasoning.
  • Internal: Satisfies the deduction theorem, but not contraposition reasoning. Should be used whenever it is important to infer the consequent even if the antecedent may be contradictory
  • Material: Does not satisfy the deduction theorem or contraposition reasoning. Important if an inclusion has to be second-guessed e.g. after a merging of knowledge bases.

It is possible to translate every axiom in the same way or decide for every axiom independently.

For further information on the theory please see:

Yue Ma, Pascal Hitzler, Zuoquan Lin, Algorithms for Paraconsistent Reasoning with OWL. In: Enrico Franconi, Michael Kifer, Wolfgang May (Eds.), The Semantic Web: Research and Applications. Proceedings of the 4th European Semantic Web Conference, ESWC2007, Innsbruck, Austria, June 2007. Springer Lecture Notes in Computer Science 4519, pp. 399-413.

User Documentation

How to install it

Just copy the inconsHandler_1.2.0.jar in the plugins directory of your installation (e.g. C:\Program Files\NeOn\NeOnToolkit\plugins). No further prerequisites are needed.

Start the Neon Toolkit, if installed correctly, you should see the orange "InconHandler" button on the top menu bar.


How to use it

Select an ontology project and push the InconHandler button. Now you can choose if you want to translate all inconsistent ontologies automatically or select the ontologies, that should be translated (e.g if you want to translate incoherent but not inconsistent ontologies):


If you choose "No" you will be asked for every ontology if you want to translate it. Note that you will be informed whether the ontology is consistent or not:


There are three ways to translate an inclusion: internal, material and strong (cf. #Functional Description). For every ontology that is going to be translated, you are asked if you want to use always the same way or decide for every axiom in the knowledge base independently:


After the translation process you may need to refresh the ontology project. Depending on the original ontology and the chosen inclusion type some new classes may appear. Now reasoning tasks with the new ontology should be possible and return results, as if the task is performed in a paraconsistent way on the original ontology.