Trackless online two-server problems and red-black games

The online 2-server problem presents a number of challenges in the search for simple competitive algorithms for solving it. Finding the optimal off-line solution involves costly dynamic programming. Looking for more efficient algorithms, researchers have studied how restriction on the input information given to the algorithm affects its competitiveness. One such restriction is tracklessness. Trackless algorithms for the 2-server problem include many known server algorithms including BALANCE_SLACK and some paging algorithms. It is demonstrated that the trackless 2-server optimization problem has a deterministic lower bound of 2311\u3e2 for competitiveness, thus proving that tracklessness is a significant restriction. The optimally competitive online non-trackless algorithm for the 2-server problem is 2-competitive. Other current research on the topic is also discussed