E L S E V I E R European Journal of Operational Research 94 (1996) 213-214

EUROPEAN JOURNAL

OF OPERATIONAL RESEARCH

Editorial

Dagstuhl Seminar on "Scheduling in Computer and Manufacturing Systems"

Jacek Bta~ewicz a, Klaus Ecker b, Jan W~glarz a

a lnstytut Informatyki, Politechnika Poznahska, Poznafi, Poland b lnstitutfiir lnformatik, Technische Universit~t Clausthal. Clausthal-ZeUerfeld. Germany

The seminar "Scheduling in Computer and Man- ufacturing Systems" was held in the Schloss Dagsthul International Center for Research in Com- puter Science in the week May 15-20, 1995. During that period 41 participants from 10 countries all over the world discussed main issues in the field of scheduling. The lectures covered both theoretical and application oriented aspects of scheduling. Areas of particular interest were problems involving multipro- cessor tasks and communication delays and shop scheduling problems.

The list of presented talks is as follows: E. Bampis (with J.C. KSnig): "Scheduling with

large communication delays". J.P. Boufflet (with J. Carlier): "'An exact method

for optimal decomposition and scheduling of an ap- plication on a bus oriented master-slaves multipro- cessor system".

P. Bouvry: "Mapping undirected task graphs on DMPC".

P. Brucker (with J. Hurink and F. Werner): "Im- proving local search heuristics for some scheduling problems".

R.E. Burkard (with E. ~ela, T. Dudas and G. Woeginger): "Minimization of noise in communica- tion networks".

J.-Y. Colin (with P. Colin): "Scheduling tasks and communications on a virtual distributed system".

Y. Crama (with J. van de Klundert): "Cyclic scheduling of identical parts in a robotic cell".

M. Dror: ""Strong-weak' constrained sched- uling' '.

M. Drozdowski (with, J. Bta2ewicz): ,Perfor- mance bounds and scheduling divisible tasks on hypercube multiprocessors".

K.H. Ecker: "Single processor scheduling prob- lems with r-width bounded task precedences".

K.H. Ecker and R. Hirscheberg: "Hypergraph approach for scheduling communication demands in networks".

G. Finke: "General flow shop models: From job overlapping to job deterioration".

L. Finta (with Z. Liu, I. Milis and E. Bampis): "Scheduling of task graphs with communication de- lays: Some positive and negative results".

V. Gordon (with T.C.E. Cheng and M. Kovalyov): "Batch delivery scheduling problems".

F. Guinand (with Ch. Rapine and D. Trystran0: "Scheduling in-trees with communication delays on identical processors".

J.N.D. Gupta: "Single facility scheduling with two operations per job and time-lags".

W.A. Halang: "Contemporary research on real- time scheduling considered obsolete".

C. Hanen: "An approximation algorithm for scheduling dependent tasks on parallel processors with small communication delays".

A. Janiak: "Scheduling problems with resources - Mathematical models, computational complexity, algorithms and applications".

0377-2217/96/$15.00 Copyright © 1996 Published by Elsevier Science B.V. All rights reserved Pll S 0 3 7 7 - 2 2 1 7 ( 9 6 ) 0 0 1 2 2 - 1

214 J. Bta~ewicz et aL / European Journal of Operational Research 94 (1996) 213-214

J. Kaiser (with H. Streich and M. Gergeleit): "DIRECT - An adaptive real-time system: Con- cepts, application, and evaluation".

R.M. Kieckhafer (with F.F. Choobineh and Y. Xue): "Using automatically generated GSPN's for performability modeling of flexible manufacturing systems with neuro-fuzzy controllers".

M.Y. Kovalyov: "Parallel machine batch schedul- ing: Algorithms, complexity, and approximation".

M. Kubale: "Open shop problem with zero-one time operations and integer release time/deadline intervals".

W. Kubiak: "Polynomial time algorithms for unit time job shops".

J.K. Lenstra (with A. Vandevelde, H. Hoogeveen and C. Hurkens): "Lower bound for the multiproces- sor flow shop".

J.K. Lenstra: "Open shop scheduling: 3 is easy, 4 is hard".

E.J. Luit: "Specification of timing requirements with timed precedence constraints".

R.H. MShring (with R. MMler): "Bounds for the project duration distribution in stochastic project".

J.R. Nawrocki: "Maximum execution time pre- diction of multi-module software".

E. Pesch: "Grouping in flexible manufacturing". J. Saner: "Knowledge-based scheduling and

meta-scheduling' '. G. Schmidt (with J. Winckler): "Office schedul-

ing". P. Solot: "Production planning in the chemical

industry". V. Sridharan (with Z. Zhou and J.J. Kane0:

"Tactically delayed scheduling". E. Toczytowski: "On a temporal decomposition

algorithm for scheduling preemptible tasks on paral- lel processors".

D. Trystram (with E. Bampis and F. Guinand): "Minimizing the overhead for tree-scheduling prob- lems".

J. W~glarz: "On discrete-continuous scheduling". F. Werner (with Y. Sotskov and Th. Tautenhahn):

"Heuristics of shop problems with batch setup times".

J. Xu (with D. Lorge Pamas): "Scheduling in hard real-time systems".

The participants appreciated the outstanding local organization and the environment, including castle Dagstuhl facilities which last but not least enabled a successful workshop.

This issue of EJOR contains 11 from among the papers presented which have passed through the normal reviewing process. The paper by M. Droz- dowski is an Invited Review and surveys one of the most rapidly developing areas of scheduling - scheduling multiprocessor tasks, each of which may require more than one processor at a time. Other papers may be grouped into a few classes depending on their contents. The first group of papers (papers by J. Bta£ewicz and Z. Liu and by M. Kubale) is concerned with particular subproblems in the area of multiprocessor task scheduling. The second group of papers (papers by E. Bampis, A. Giannakos and J.C. KSnig, by E. Bampis, F. Guinand and D. Trystram, and by J. Colin and P. Colin) deals with communica- tion issues arising in the context of modem parallel computer systems where different modules of the same program can be assigned to different proces- sors. The third group of papers (papers by T.C. Cheng, V.S. Gordon and H.Y. Kovalyov, by A. Janiak and M.Y. Kovalyov, and by V. Sridharan and Z. Zhou) solves some open questions concerning one-machine scheduling problems with additional constraints concerning a usage of scarce resources. Finally, papers by J. J6zefowska and J. W~glarz and by M. Kubiak and V. Timkovsky present new ap- proaches for the total completion time minimization for the resource allocation problem and two-machine job shops, respectively.