TY - JOUR

T1 - Online edge coloring of paths and trees with a fixed number of colors

AU - Favrholdt, Lene M.

AU - Mikkelsen, Jesper W.

PY - 2018

Y1 - 2018

N2 - We study a version of online edge coloring, where the goal is to color as many edges as possible using only a given number, k, of available colors. All of our results are with regard to competitive analysis. Previous attempts to identify optimal algorithms for this problem have failed, even for bipartite graphs. Thus, in this paper, we analyze even more restricted graph classes, paths and trees. For paths, we consider k= 2 , and for trees, we consider any k≥ 2. We prove that a natural greedy algorithm called FIRST-FIT is optimal among deterministic algorithms, on paths as well as trees. For paths, we give a randomized algorithm, which is optimal and better than the best possible deterministic algorithm. For trees, we prove that to obtain a better competitive ratio than FIRST-FIT, the algorithm would have to be both randomized and unfair (i.e., reject edges that could have been colored), and even such algorithms cannot be much better than FIRST-FIT.

AB - We study a version of online edge coloring, where the goal is to color as many edges as possible using only a given number, k, of available colors. All of our results are with regard to competitive analysis. Previous attempts to identify optimal algorithms for this problem have failed, even for bipartite graphs. Thus, in this paper, we analyze even more restricted graph classes, paths and trees. For paths, we consider k= 2 , and for trees, we consider any k≥ 2. We prove that a natural greedy algorithm called FIRST-FIT is optimal among deterministic algorithms, on paths as well as trees. For paths, we give a randomized algorithm, which is optimal and better than the best possible deterministic algorithm. For trees, we prove that to obtain a better competitive ratio than FIRST-FIT, the algorithm would have to be both randomized and unfair (i.e., reject edges that could have been colored), and even such algorithms cannot be much better than FIRST-FIT.

U2 - 10.1007/s00236-016-0283-0

DO - 10.1007/s00236-016-0283-0

M3 - Journal article

AN - SCOPUS:84994314534

SN - 0001-5903

VL - 55

SP - 57

EP - 80

JO - Acta Informatica

JF - Acta Informatica

ER -