# Travelling salesman problem

**THEOREM**
"The problem has been shown to be NP-hard (more precisely, it is complete for the complexity class FP^(NP); see function problem), and the decision problem version ("given the costs and a number x, decide whether there is a round-trip route cheaper than x") is NP-complete."
Theorem: The travelling salesman problem is NP-hard, and its decision-variant is NP-complete.
TODO: Proof

Proof unavailable