It was previously known that neither Max Clique nor Min Chromatic Number can be approximated in polynomial time within n1-e, for any constant e > 0, unless NP = ZPP. In this paper, we extend the reductions used to prove these results and combine the extended reductions with a recent result of Samorodnitsky and Trevisan to show that unless NP ⊆ ZPTIME(2O(log n(log log n)3/2)), neither Max Clique nor Min Chromatic Number can be approximated in polynomial time within n1-e(n) where e ∈ O((log log n)-1/2). Since there exists polynomial time algorithms approximating both problems within n1-e(n) where e(n) ∈ Ω(log log n/log n), our result shows that the best possible ratio we can hope for is of the form n1-o(1), for some--yet unknown--value of o(1) between O((log log n)-1/2) and Ω(log log n/log n).
Towards optimal lower bounds for clique and chromatic number
Lars Engebretsen,Jonas Holmerin
Published 2003 in Theoretical Computer Science
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- Publication year
2003
- Venue
Theoretical Computer Science
- Publication date
2003-04-18
- Fields of study
Mathematics, Computer Science
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