Papers by Patch Uthaisombut
The real-time kinetic (RK) model for studying kinetic problems is introduced. We considered algor... more The real-time kinetic (RK) model for studying kinetic problems is introduced. We considered algorithms that maintain, in real time, the attributes of interests of systems that evolve continuously and unpredictably over time. This works differ from kinetic data structures (KDS) introduced by Guibas 1998 in two ways. First, the algorithm learns the position of moving objects in a completely online fashion. Instead we assume that the speed of any object at any time is no greater than a certain maximum speed Smax. Second, the algorithms that maintains the attributes of interest of the system runs in real time, that is, the algorithms run while the objects are moving at the same time. We consider the problem of maintaining the approximate sorted order of moving points on the line. We give an algorithm that has a maximum error of O(Smaxn) where n is the number of objects. Note that the naive method of running a static sorting algorithm repeatedly over time has a maximum error of Ω(Smaxn l...
Theory of Computing Systems, 2007
We consider the problem of speed scaling to conserve energy in a multiprocessor setting where the... more We consider the problem of speed scaling to conserve energy in a multiprocessor setting where there are precedence constraints between tasks, and where the performance measure is the makespan. That is, we consider an energy bounded version of the classic problem P m | prec | Cmax. We show that, without loss of generality, one need only consider constant power schedules. We then show how to reduce this problem to the problem Qm | prec | Cmax to obtain a poly-log(m)approximation algorithm.
Algorithmica, 2007
It is well known that the Earliest-Deadline-First (EDF) and the Least-Laxity-First (LLF) algorith... more It is well known that the Earliest-Deadline-First (EDF) and the Least-Laxity-First (LLF) algorithms are optimal algorithms for the problem of preemptively scheduling jobs that arrive over time on a single machine to minimize maximum lateness (1|r j , pmtn|L max). It was not previously known what other online algorithms are optimal for this problem. As this problem is a fundamental problem in machine scheduling, it deserves a thorough investigation. In this paper, the concept of compound laxity is introduced, and a complete characterization of all optimal online algorithms for this problem is derived.
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Papers by Patch Uthaisombut