<Table> <Tr> <Td> </Td> <Td> This section needs expansion . You can help by adding to it . (January 2015) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section needs expansion . You can help by adding to it . (January 2015) </Td> </Tr> <P> NP - hard problems are often tackled with rules - based languages in areas including: </P> <Ul> <Li> Approximate computing </Li> <Li> Configuration </Li> <Li> Cryptography </Li> <Li> Data mining </Li> <Li> Decision support </Li> <Li> Phylogenetics </Li> <Li> Planning </Li> <Li> Process monitoring and control </Li> <Li> Rosters or schedules </Li> <Li> Routing / vehicle routing </Li> <Li> Scheduling </Li> <Li> Selection </Li> <Li> Tutoring systems </Li> </Ul>

When do you say a problem is np - hard give examples