For example if one wants to define what an uncle is, then one has to define some Property which means that an uncle is some Brother of one of a Parent. This is somekind of a Property Chain, because on chains one Property to another Property, e.g.
isBorther, therefore one defines
 rdf:type owl:negativePropertyAssertion ; owl:sourceIndividual :Kain ; owl:assertProperty :isBrother ; owl:targetIndividual :Abel . Philosopher ⊑ knows.self