摘要: Lovasz, Saks, and Trotter showed that there exists an on-line algorithm which will color any on-linek-colorable graph onn vertices withO(nlog(2k−3) n/log(2k−4) n) colors. Vishwanathan at least Ω(log k−1 n/k k ) colors are needed. While these remain the best known bounds, they give a distressingly weak approximation of number required. In this article we study case perfect graphs. We prove withn 10k/loglogn Vishwanathan's techniques can be slightly modified to show his lower bound also holds for This suggests is far from tight in general case.