In the job shop scheduling problem -units-, there are machines and each machine has an integer processing time of at most time units. Each job consists of a permutation of tasks corresponding to all machines and thus all jobs have an identical dilation . The contribution of this paper are the following results; (i) for jobs and every fixed , the makespan of an optimal schedule is at most , which extends the result of [3] for ; (ii) a randomized on-line approximation algorithm for -units- is presented. This is the on-line algorithm with the best known competitive ratio against an oblivious adversary for and ; (iii) different processing times yield harder instances than identical processing times. There is no competitive deterministic on-line algorithm for -units-, whereas the competitive ratio of the randomized on-line algorithm of (ii) still tends to 1 for .
Mots-clés : on-line algorithms, randomization, competitive ratio, scheduling
@article{ITA_2009__43_2_189_0, author = {M\"omke, Tobias}, title = {On the power of randomization for job shop scheduling with $k$-units length tasks}, journal = {RAIRO - Theoretical Informatics and Applications - Informatique Th\'eorique et Applications}, pages = {189--207}, publisher = {EDP-Sciences}, volume = {43}, number = {2}, year = {2009}, doi = {10.1051/ita:2008024}, mrnumber = {2512254}, zbl = {1166.68041}, language = {en}, url = {http://archive.numdam.org/articles/10.1051/ita:2008024/} }
TY - JOUR AU - Mömke, Tobias TI - On the power of randomization for job shop scheduling with $k$-units length tasks JO - RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications PY - 2009 SP - 189 EP - 207 VL - 43 IS - 2 PB - EDP-Sciences UR - http://archive.numdam.org/articles/10.1051/ita:2008024/ DO - 10.1051/ita:2008024 LA - en ID - ITA_2009__43_2_189_0 ER -
%0 Journal Article %A Mömke, Tobias %T On the power of randomization for job shop scheduling with $k$-units length tasks %J RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications %D 2009 %P 189-207 %V 43 %N 2 %I EDP-Sciences %U http://archive.numdam.org/articles/10.1051/ita:2008024/ %R 10.1051/ita:2008024 %G en %F ITA_2009__43_2_189_0
Mömke, Tobias. On the power of randomization for job shop scheduling with $k$-units length tasks. RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications, Tome 43 (2009) no. 2, pp. 189-207. doi : 10.1051/ita:2008024. http://archive.numdam.org/articles/10.1051/ita:2008024/
[1] An efficient algorithm for the job shop problem with two jobs. Computing 40 (1988) 353-359. | MR | Zbl
,[2] Improved bounds for acyclic job shop scheduling. Combinatorica 22 (2002) 361-399. | MR
and ,[3] Job shop scheduling with unit length tasks: bounds and algorithms. ICTCS '01: Proceedings of the 7th Italian Conference on Theoretical Computer Science. Lect. Notes Comput. Sci. 2202 (2001) 90-106. | MR | Zbl
, and ,[4] Job shop scheduling with unit length tasks: bounds and algorithms. Algorithmic Operations Research 2 (2007) 1-14. | MR
, , and ,[5] Packet routing and job shop scheduling in steps. Combinatorica 14 (1994) 167-186. | MR | Zbl
, and ,[6] Fast algorithms for finding packet routing schedules. Combinatorica 19 (1999) 375-401. | MR | Zbl
, and ,[7] Computational complexity of discrete optimization problems. Annals of Discrete Mathematics 4 (1979) 121-140. | MR | Zbl
and ,[8] Short shop schedules. Operations Research 45 (1997) 288-294. | MR | Zbl
, , , , and ,Cité par Sources :