ApprxAlgorithms/ComboOpt
Many important problems that arise in practical applications of discrete optimization are NP-hard. This implies no polynomial time algorithms exist for these problems unless P==NP. The field of approximation algorithms has developed to tackle this difficulty by designing polynomial time algorithms to solve otherwise intractable problems near-optimally. Approximation algorithms provide rigorous guarantees on approximation factors indicating how far the solution can be in the worst case.