<P> Another critical difference is the way the model treats information that is currently not in the system . Programming objects and most database systems use the "closed - world assumption". If a fact is not known to the system that fact is assumed to be false . Semantic Web objects use the open - world assumption, a statement is only considered false if there is actual relevant information that it is false, otherwise it is assumed to be unknown, neither true nor false . </P> <P> OWL objects are actually most like objects in artificial intelligence frame languages such as KL - ONE and Loom . </P> <P> The following table contrasts traditional objects from Object - Oriented programming languages such as Java or C++ with Semantic Web Objects: </P> <Table> <Tr> <Th> OOP Objects </Th> <Th> Semantic Web Objects </Th> </Tr> <Tr> <Td> Classes are regarded as types for instances . </Td> <Td> Classes are regarded as sets of individuals . </Td> </Tr> <Tr> <Td> Instances cannot change their type at runtime . </Td> <Td> Class membership may change at runtime . </Td> </Tr> <Tr> <Td> The list of classes is fully known at compile - time and cannot change after that . </Td> <Td> Classes can be created and changed at runtime . </Td> </Tr> <Tr> <Td> Compilers are used at build - time . Compile - time errors indicate problems . </Td> <Td> Reasoners can be used for classification and consistency checking at runtime or build - time . </Td> </Tr> <Tr> <Td> Classes encode much of their meaning and behavior through imperative functions and methods . </Td> <Td> Classes make their meaning explicit in terms of OWL statements . No imperative code can be attached . </Td> </Tr> <Tr> <Td> Instances are anonymous insofar that they cannot easily be addressed from outside of an executing program . </Td> <Td> All named RDF and OWL resources have a unique URI under which they can be referenced . </Td> </Tr> <Tr> <Td> Closed world: If there is not enough information to prove a statement true, then it is assumed to be false . </Td> <Td> Open world: If there is not enough information to prove a statement true, then it may be true or false . </Td> </Tr> </Table>

Which one of the following is not true of a class and an object