Here, we will show a transformation pattern which should improve reasoning
performance in Pellet reasoner. This is based on
documentation in Pellet distribution. Particularly, it is related to pellint
tool, `http://pellet.owldl.com/pellint`, which is a lint tool for
OWL ontologies detecting problematic modelling constructs regarding ontology's
reasoning performance in Pellet. There are defined two kinds of patterns
for improving reasoning:

- axiom-based consisting of one axiom,
- ontology-based consisting of more than one axiom in an ontology.

<op1> <entity_declarations> <placeholder type="Class">?A</placeholder> <placeholder type="Class">?B</placeholder> <placeholder type="Class">?C</placeholder> <placeholder type="Class">?D</placeholder> <placeholder type="ObjectProperty">?p</placeholder> </entity_declarations> <axioms> <axiom>?A equivalentTo (?B and ?C)</axiom> <axiom>?A subClassOf (?p only ?D)</axiom> </axioms> </op1>

Corresponding OP2 is serialized as follows:

<op2> <entity_declarations> <placeholder type="Class">?E</placeholder> <placeholder type="Class">?F</placeholder> <placeholder type="Class">?G</placeholder> <placeholder type="Class">?H</placeholder> <placeholder type="ObjectProperty">?q</placeholder> </entity_declarations> <axioms> <axiom>?E subClassOf (?F and ?G)</axiom> <axiom>?E subClassOf (?q only ?H)</axiom> </axioms> </op2>

A simple pattern transformation:

<pt> <eq op1="?A" op2="?E"/> <eq op1="?B" op2="?F"/> <eq op1="?C" op2="?G"/> <eq op1="?D" op2="?H"/> <eq op1="?p" op2="?q"/> </pt>

This ensures the desired transformation where the problematic concept is removed from the equivalent classes axiom and new subclass axiom is added.

This simple transformation pattern demonstrates potential usage of
transformation patterns in reasoning scenario. In this case, it is related to
Pellet reasoner, `http://clarkparsia.com/pellet/`. However, there
are also other reasoners for which specific requirements regarding reasoning
performance could be specified in future work e.g.
Fact++, `http://owl.man.ac.uk/factplusplus`,
HermiT, `http://hermit-reasoner.com/`.

ondrej 2011-06-21