homework: proof the inconsistencies

I would like to see the inconsistencies in the stuff that I get
i.e. I would like to see the (hopefully not found) proofs for
e.g. the following sets of statements

  { _:x a _:y . _:x a _:z . _:y ont:complementOf _:z }

  { _:x a _:y . _:x a _:z . _:y ont:disjointWith _:z }

  { _:x a _:y . _:x a _:z . _:d a ont:Disjoint; :member _:y; :member _:z .
    _:y ont:differentIndividualFrom _:z }

  { _:x contact:mailbox _:o . _:y contact:mailbox _:o .
    _:x ont:differentIndividualFrom _:y }

  { _:x gc:parent _:y . _:y gc:parent _:x }

  { _:x gc:parent _:y . _:y gc:parent _:z . _:x gc:parent _:z }


--
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/