  Reasoning with ontologies is one of the core fields of research in
Description Logics. A variety of efficient reasoner with highly optimized
algorithms have been developed to allow inference tasks on expressive ontology
languages such as OWL(DL). However, reasoner reported computing times have
exceeded and sometimes fall behind the expected theoretical values. From an
empirical perspective, it is not yet well understood, which particular aspects
in the ontology are reasoner performance degrading factors. In this paper, we
conducted an investigation about state of art works that attempted to portray
potential correlation between reasoner empirical behaviour and particular
ontological features. These works were analysed and then broken down into
categories. Further, we proposed a set of ontology features covering a broad
range of structural and syntactic ontology characteristics. We claim that these
features are good indicators of the ontology hardness level against reasoning
tasks.
