Approximation algorithms for stochastic scheduling on unrelated machines

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 59-60).Motivated by problems in distributed computing, this thesis presents the first nontrivial polynomial time approximation algorithms for an important class of machine scheduling problems. We study the family of preemptive minimum makespan scheduling problems where jobs have stochastic processing requirements and provide the first approximation algorithms for these problems when machines have unrelated speeds. We show a series of algorithms that apply given increasingly general classes of precedence constraints on jobs. Letting n and m be, respectively, the number of jobs and machines in an instance, when jobs need an exponentially distributed amount of processing, we give: -- An O(log log min {m, n} )-approximation algorithm when jobs are independent; -- An 0 (log(n + m) log log min {m, n})-approximation algorithm when precedence constraints form disjoint chains; and, -- An O(log n log(n + m) log log min {m, n} )-approximation algorithm when precedence constraints form a directed forest. Very simple modifications allow our algorithms to apply to more general distributions, at the cost of slightly worse approximation ratios. Our O(log log n)-approximation algorithm for independent jobs holds when we allow restarting instead of preemption. Here jobs may switch machines, but lose all previous processing if they do so. We also consider problems in the framework of scheduling under uncertainty. This model considers jobs that require unit processing on machines with identical speeds. However, after processing a job to completion, a machine has an (unrelated) probability of failing and leaving the job uncompleted. This difficulty is offset by allowing multiple machines to process a job simultaneously. We prove that this model is equivalent to a slightly modified version of the family of problems described above and provide approximation algorithms for analogous problems with identical ratios.by Jacob Scott.S.M

Scheduling Algorithms for Parallel Execution of Computer Programs

Computer Scienc

Central Florida Future, Vol. 17 No. 21, February 15, 1985

McCollum favors funds for rebels; Graham stabs students; Senators walk out to save measure; AROUND UCF: ENGINEER FAIR; AROUND AMERICA: ATHLETES RATE ALCOHOL; Conference gives insight into student lobbying; College looks for a few good chairmen; Dormitories may get reserved parking; Opinion: Governor Graham puts the screws to students; Sports: UCF Knights defeat FIT; UCF soccer players receive honors (with photos of Jean Varas and Michelle Akers); Gators defeat Knight baseball team, 9-4; Surfers go to nationals; Going to a Go-Go; Good cast, original plot highlight \u27Heaven\u27; How not to get shot down at bars.https://stars.library.ucf.edu/centralfloridafuture/1566/thumbnail.jp

January 17, 1975

The Breeze is the student newspaper of James Madison University in Harrisonburg, Virginia

The United Nations Military Observer Group in India and Pakistan (UNMOGIP) 1948-1965, with postscript on the impact on UNMOGIP of the Indo-Pakistan war of 1971

In January 1949 the first UN Military Observers arrived in Kashmir to supervise a ceasefire between India and Pakistan, following hostilities arising from Kashmir's disputed status after Independence. In-accepting the resolutions of a UN Commission which had been despatched to the area, and by ratifying the Karachi Agreement of July 1949, India and Pakistan committed themselves to accepting the presence of Observers until the Dispute was resolved. This thesis gives an overall view of UNMOGIP. it describes the background to the Dispute and the emergence, organisation and modus operandi of the Mission. It attempts to analyse UNMOGIP's contribution to the maintenance of peace by highlighting the Mission's efforts at stabilizing the situation. Considerable mention is made of civilians who were the major cause of incidents. The thesis supports the view that for fifteen years UNMOGIP successfully assisted the parties in their desire for peace, but when this desire faltered a small group of Observers was unable to save the situation. Thus after five years of deteriorating relations between civilians and police along the Ceasefire Line, war again erupted for seventeen days in September 1965. The Observers had virtually to suspend operations until a further Ceasefire was called. Even then it was not until the Indian and Pakistan leaders reached a Political agreement in Tashkent in January 1966 that the Ceasefire truly held, and the withdrawal of forces was able to take place under the supervision of the Observers. In 1972, after another war, the two parties agreed to solve their problems bi-laterally, and India maintained that UNMOGIP had no further function to perform. Unable to obtain Pakistan's or the UN's consent to the Mission's withdrawal, she withdrew her own co-operation. UNMOGIP has not since been able to operate on the Indian side although it remains in position