NamespacePrefix(ret ) RequestMessage( CreateKB(Attribute(kb )) Tell( Attribute(kb ) owl.ClassAssertion( )) GetInstances( Attribute(kb ) Attribute(direct "false") ) ret.Retract( Attribute( ) owl.ClassAssertion( )) GetInstances( Attribute(kb ) Attribute(direct "false") ) ReleaseKB( Attribute(kb )))