Opsearch, Vol. 34, No. 2, 1997 0030-3887/95 $ 2.00 + 0.00 © Operational Research Society of India SHORT NOTE Sequencing with Restrictions in Processing Times P.C. Bagga Moti Lal Nehru College (E), University of Delhi & Ambika Bhambani Jesus and Mary College, University of Delhi Abstract Johnson, Szwarc gave the algorithm for obtaining the sequence which minimizes the total elapsed time for n-jobs-3 machines problem when the processing time of jobs on these machines possess certain conditions. This paper yields the algorithm for general flow shop problems. 1. INTRODUCTION In-n-job m-machine flow shop problem, the aim is to obtain a sequence of jobs which' when processed on these machines (in the predefined order of machines) minimizes the total elapsed time. Johnson gave the algorithm for n-job 3-machine problem when (i) Y(i,l) Y(j,2) ( ii ) Y ( i , 3) Y ( j , 2 ) Szwarc gave the algorithm when -tt-i & j ; i :F j -V-i & j ; i :F j (iii) Y ( i , 1 ):S; Y ( j , 2) ; -tt- i & j ; i :F j (iv ) Y ( i , 3):s; Y ( j , 2 ) ; -V- i & j ; i :F j Where Y ( i, k) is the processing time of job i on machine k (i= 1,2, ... ,n; k= 1,2,3) The present paper extends these to m machine case and provides a simple algorithm when the processing time of jobs satisfy certain conditions.