own-en.ttl doesn't look like valid OWL 2 DL

[fcbr]

We get the following error from HermiT and FaCT++.

2018-05-10 08:07:50.329 [Classification Thread] ERROR OWLReasonerManager    
An error occurred during reasoning: Non-simple property '<schema:hypernymOf>' 
or its inverse appears in asymmetric object property axiom.
[stack trace omitted]

Relevant URLs:

• https://www.w3.org/TR/owl2-syntax/#Property_Hierarchy_and_Simple_Object_Property_Expressions
• https://mailman.stanford.edu/pipermail/protege-discussion/2012-May/005972.html
• http://protege-project.136.n4.nabble.com/Simple-object-property-td4658227.html
• https://www.w3.org/TR/wordnet-rdf/
• https://arxiv.org/pdf/1212.2902.pdf (section 2.2, discussion on global restrictions)

[fcbr]

Complex properties can't be IrreflexiveObjectProperty or AsymmetricObjectProperty, according to link [1] above (section 11.2, Restriction on Simple Roles).

It looks like hypernymOf and hyponymOf are considered complex properties since they are TransitiveObjectProperty and thus "composite" (see section 11.1 from the same document).

So we need to choose which axioms to remove: transitive or (irreflexive+asymmetric).

[arademaker]

I will need some time to read the references, very strange for me this restriction.