We investigate an online scheduling problem on a bounded batch machine with f incompatible job families, in which the jobs are released over time and the jobs belonging to the same family have the same processing time...
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We investigate an online scheduling problem on a bounded batch machine with f incompatible job families, in which the jobs are released over time and the jobs belonging to the same family have the same processing times. The goal is to minimize the maximum completion time. A machine can process at most b jobs simultaneously as a batch, where b is finite. A batch only contains the jobs from the same family. KRT setting means that no job is released when the machine is busy. In this paper, we consider the above model under two environments: (1) KRT setting and (2) general setting. In the KRT setting, we provide the lower bounds 1 +root f(2) -f+1-1 /(f) for b >= f and min {(2f+1)/ (f+2) , (2b )/(b+1)} for 2 <= b < f. In the general setting, we provide the lower bounds 1 + root 4f(2) +1-1/ (2f) for b >= f + 1 and (2b)/( b+1) for 2 <= b < f + 1. We further present an online algorithm, which is the best possible when b >= f for the KRT setting and when b >= f + 1 for the general setting.
We analyze the competitive ratio and the advice complexity of the online unbounded knapsack problem. An instance is given as a sequence of n items with a size and a value each, and an algorithm has to decide whether o...
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We analyze the competitive ratio and the advice complexity of the online unbounded knapsack problem. An instance is given as a sequence of n items with a size and a value each, and an algorithm has to decide whether or not and how often to pack each item into a knapsack of bounded capacity. The items are given online and the total size of the packed items must not exceed the knapsack's capacity, while the objective is to maximize the total value of the packed items. While each item can only be packed once in the classical knapsack problem (also called the 0-1 knapsack problem), the unbounded version allows for items to be packed multiple times. We show that the simple unbounded knapsack problem, where the size of each item is equal to its value, allows for a competitive ratio of 2. We also analyze randomized algorithms and show that, in contrast to the 0-1 knapsack problem, one uniformly random bit cannot improve an algorithm's performance. More randomness lowers the competitive ratio to less than 1.736, but it can never be below 1.693. In the advice complexity setting, we measure how many bits of information (so-called advice bits) the algorithm has to know to achieve some desired solution quality. For the simple unbounded knapsack problem, one advice bit lowers the competitive ratio to 3/2. While this cannot be improved with fewer than loglog22nn advice bits for instances of length n, a competitive ratio of 1 + epsilon can be achieved with O(epsilon(-1 ) log(n epsilon(-1))) advice bits for any epsilon > 0. We further show that no amount of advice bounded by a function f(n) allows an algorithm to be optimal. We also study the online general unbounded knapsack problem and show that it does not allow for any bounded competitive ratio for both deterministic and randomized algorithms, as well as for algorithms using fewer than log(2)n advice bits. We also provide a surprisingly simple algorithm that uses O(epsilon(-1 ) log(n epsilon(-1))) advice
This paper describes a fundamental online scheduling problem called the minimum peak job scheduling (MPJS) problem. In this problem, there is a sequence of arriving jobs, each with a specified required scheduled time ...
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This paper describes a fundamental online scheduling problem called the minimum peak job scheduling (MPJS) problem. In this problem, there is a sequence of arriving jobs, each with a specified required scheduled time for one unit of a scarce and reusable resource. The goal is to schedule each job upon arrival within a scheduling interval to minimize the resulting peak utilization (i.e., the maximum number of units used simultaneously throughout the entire scheduling interval). The MPJS problem captures many practical settings of real-time appointment scheduling. Its offline version where all jobs are known in advance is equivalent to the well-known bin-packing problem, where jobs correspond to items and the unit resource is a bin. However, the online variant of MPJS allows additional flexibility in that initially, one only commits to the scheduling time, but the allocation to the resources can be done later. In the bin-packing problem, this corresponds to the ability to move items across bins. Some relaxed versions of online bin-packing problems have already been studied, but none fundamentally capture the MPJS model studied in this paper. The paper describes the first competitive online algorithm to the MPJS problem called the harmonic rematching (HR) algorithm. The analysis shows that the HR algorithm has an asymptotic competitive ratio below 1.5. The fact that the current best lower bound on randomized online algorithms for the bin-packing problem is 1.536 highlights the fundamental difference between these two related models.
As market competition intensifies, modern enterprises prioritize customer demands, leading to an increased emphasis on multi-variety and small-batch production. In this article, we study the online scheduling problem ...
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As market competition intensifies, modern enterprises prioritize customer demands, leading to an increased emphasis on multi-variety and small-batch production. In this article, we study the online scheduling problem for incompatible batch processing with the deterioration effect to minimize the maximum delivery completion time in the billet rolling process, where the batch capacity and delivery capacity are unbounded. We assume that the processing time of job J(j )is expressed as p(j )= a(j)(A + Bt), where A > 0, B > 0, t denotes the start time of job and a(j) > 0 represents the job's processing deterioration rate. For such an online problem, we first prove that the lower bound of the problem is (1+Ba-max)(k), where k denotes the number of job families and a(max )represents the maximum deterioration ratio in job instance. Then we design an online algorithm Largest Delivery Time With Batch Processing and demonstrate that the competitive ratio of the algorithm is no more than 1+(1+Ba-max)(k). Finally, experiments on randomly generated instances prove that our algorithm is reasonable and effective.
We address an online scheduling problem on a batch machine to minimize the makespan. Jobs are released online over time and can be grouped into batches simultaneously with equal-processing times. This batch machine ha...
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We address an online scheduling problem on a batch machine to minimize the makespan. Jobs are released online over time and can be grouped into batches simultaneously with equal-processing times. This batch machine has periodic pulse interruptions, which are machine unavailable periods with negligible length. The pulse interruptions divide the scheduling horizon into periodic available intervals. A batch can be processed only within an available interval without any preemption. For all possible equal-processing times, we develop the lower bounds on competitive ratios and provide optimal online algorithms when the batch capacity is unbounded and bounded, respectively. (c) 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
On a ring, given m servers and m requests arriving one by one in an online fashion. Upon each request arrival, it needs to be immediately matched to a server, generating a matching distance on the ring. The objective ...
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ISBN:
(纸本)9789819614899;9789819614905
On a ring, given m servers and m requests arriving one by one in an online fashion. Upon each request arrival, it needs to be immediately matched to a server, generating a matching distance on the ring. The objective is to find a matching where each server and each request are strictly matched once, minimizing the maximum matching distance. When the m servers are evenly distributed on the ring, we prove that the classical greedy algorithm achieves an optimal competitive ratio of m. When m = 3, using polar coordinates to partition the ring into three intervals, we provide optimal online algorithms for four parameter scenarios where the competitive ratio depends on the server spacing ratio.
In the production scheduling of prefabricated components, a scheduling model considering the learning effect of processing time and the deterioration effect of delivery time in this paper is provided. More precisely, ...
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In the production scheduling of prefabricated components, a scheduling model considering the learning effect of processing time and the deterioration effect of delivery time in this paper is provided. More precisely, it asks for an assignment of a series of independent prefabricated jobs that arrived over time to a single machine for processing, and once the execution of a job is finished, it will be transported to the destination. The information of each prefabricated job including its basic processing time bj\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$b_{j}$$\end{document}, release time rj\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$r_j$$\end{document}, and deterioration rate ej\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e_j$$\end{document} of delivery time is unknown in advance and is revealed upon the arrival of this job. Moreover, the actual processing time of prefabricated job Jj\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$J_j$$\end{document} with learning effect is pj=bj(a-bt)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p_{j}=b_{j}(a-b t)$$\end{docum
In this paper we investigate a variant of the scheduling problem on two uniform machines with speeds 1 and s. For this problem, we are given two potential uniform machines to process a sequence of independent jobs. Ma...
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In this paper we investigate a variant of the scheduling problem on two uniform machines with speeds 1 and s. For this problem, we are given two potential uniform machines to process a sequence of independent jobs. Machines need to be activated before starting to process, and each machine activated incurs a fixed machine activation cost. No machines are initially activated, and when a job is revealed, the algorithm has the option to activate new machines. The objective is to minimize the sum of the makespan and the machine activation cost. We design optimal online algorithms with competitive ratio of (2s+1)/(s+1) for every s≥1.
This work investigates the online multiple time series search problem. Given a storage with finite capability, a player receives one product for sale and observes a selling price as well at each period. With the knowl...
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This work investigates the online multiple time series search problem. Given a storage with finite capability, a player receives one product for sale and observes a selling price as well at each period. With the knowledge that prices in all periods vary within [m,M] (0 < m < M), the player decides at the period whether to sell some of the products in the storage together with the one currently received at the price observed or to store the current one in the storage. Our main contributions are three online algorithms TRPP, SOEP and IS where IS is a combination of TRPP and SOEP, and their competitiveness analyses. Moreover, we prove a lower bound of the competitive ratio for the problem, and prove that 7S is optimal as the ratio M/m goes to infinity. Numerical computation further shows that the gap between the upper and lower bounds first increases and then decreases as M/m rises. (C) 2011 Elsevier Ltd. All rights reserved.
In this paper, we introduce the mixed ring loading problem, where the ring contains undirected and bidirected links. When the ring consists of two nodes, we consider the online mixed ring loading problem under three d...
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In this paper, we introduce the mixed ring loading problem, where the ring contains undirected and bidirected links. When the ring consists of two nodes, we consider the online mixed ring loading problem under three different scenarios including splittable, integer splittable and unsplittable. When the demands are (integer) splittable, we present an (asymptotically) optimal online algorithm. When the demands are unsplittable, we present an online algorithm which generalizes the previous result.
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