NP-hard
<complexity> A set or property of computational
search problems.
A problem is NP-hard if solving it in polynomial time would make it possible to solve all problems in class
NP in polynomial time.
Some NP-hard problems are also in
NP (these are called "
NP-complete"), some are not.
If you could reduce an
NP problem to an NP-hard problem and then solve it in polynomial time, you could solve all NP problems.
See also
computational complexity.
[Examples?]
