Exhaustive manual review of documents to determine their relevancy for a given purpose is error-prone and resource intensive. This has led to the consideration of computer-aided processes where only a small subset of ...
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ISBN:
(纸本)9781450395175
Exhaustive manual review of documents to determine their relevancy for a given purpose is error-prone and resource intensive. This has led to the consideration of computer-aided processes where only a small subset of the entire set of documents is manually reviewed with comparable performance as exhaustive manual review, resulting in the reduction of human-introduced error and allocated resources. As more evidence for the superiority of Technology-Assisted Reviews (TAR) becomes available, researchers and practitioners have resorted to the exploration of various methods to improve process efficiency without significant degradation in output quality. Of particular interest in this process is the decision on when to stop reviewing additional documents. We consider and evaluate online algorithms, specifically a solution to the multiple choice secretary problem, which is a natural fit for this purpose. Unlike in extant TAR methods, only the relative ranking among the documents that have already been retrieved is needed for this algorithm. Our results indicate that online algorithms are a competitive choice for TAR applications.
In online scenarios requests arrive over time, and each request must be serviced in an irrevocable manner before the next request arrives. online algorithms with advice is an area of research where one attempts to mea...
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In online scenarios requests arrive over time, and each request must be serviced in an irrevocable manner before the next request arrives. online algorithms with advice is an area of research where one attempts to measure how much knowledge of future requests is necessary to achieve a given performance level, as defined by the competitive ratio. When this knowledge, the advice, is obtainable, this leads to practical algorithms, called semi-online algorithms. On the other hand, each negative result gives robust results about the limitations of a broad range of semi-online algorithms. This survey explains the models for online algorithms with advice, motivates the study in general, presents some examples of the work that has been carried out, and includes an extensive set of references, organized by problem studied.
online algorithms that allow a small amount of migration or recourse have been intensively studied in the last years. They are essential in the design of competitive algorithms for dynamic problems, where objects can ...
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ISBN:
(数字)9783030394790
ISBN:
(纸本)9783030394790;9783030394783
online algorithms that allow a small amount of migration or recourse have been intensively studied in the last years. They are essential in the design of competitive algorithms for dynamic problems, where objects can also depart from the instance. In this work, we give a general framework to obtain so called robust online algorithms for a variety of dynamic problems: these online algorithms achieve an asymptotic competitive ratio of gamma + epsilon with migration O(1/epsilon), where gamma is the best known offline asymptotic approximation ratio. For our framework, we require only two ingredients: (i) the existence of an online algorithm for the static case (without departures) that provides a provably good solution compared to the total volume of the instance and (ii) that the optimal solution always exceeds this total volume. If these criteria are met, we can complement the online algorithm with any offline algorithm. While these criteria are naturally fulfilled by many dynamic problems, they are especially suited for packing problems. In order to show the usefulness of our approach in this area, we improve upon the best known robust algorithms for the dynamic versions of generalizations of Strip Packing and Bin Packing, including the first robust algorithms for general d-dimensional Bin Packing and Vector Packing.
Two-sided platforms rely on their recommendation algorithms to help their visitors successfully find a match. However, on platforms such as VolunteerMatch - which has facilitated tens of millions of connections betwee...
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ISBN:
(纸本)9781450391504
Two-sided platforms rely on their recommendation algorithms to help their visitors successfully find a match. However, on platforms such as VolunteerMatch - which has facilitated tens of millions of connections between volunteers and nonprofits - a sizable fraction of website traffic arrives directly to a nonprofit's volunteering page via an external link, thus bypassing the platform's recommendation algorithm. We study how such platforms should account for this external traffic in the design of their recommendation engines, given the goal of maximizing the total number of successful matches. We model the platform's problem as a special case of online matching with stochastic rewards, where (using VolunteerMatch as a motivating example) volunteers arrive sequentially and (probabilistically) match with one opportunity, each of which has finite need for volunteers. In our framework, external traffic is interested only in their targeted opportunity; in contrast, internal traffic may be interested in many opportunities, and the platform's online algorithm selects which opportunity to recommend. In evaluating the performance of different algorithms, we take a worst-case analysis approach, yet we refine the notion of the competitive ratio by parameterizing it based on the amount of external traffic. After demonstrating the shortcomings of a commonly-used algorithm which is optimal in the absence of external traffic, we introduce a new algorithm - Adaptive Capacity (AC) - which accounts for matches differently based on whether they originate from internal or external traffic. We establish a lower bound on AC's competitive ratio that is increasing in the amount of external traffic, and we compare our lower bound to a parameterized upper bound on the competitive ratio of any online algorithm. We find that (in certain parameter regimes) AC is near-optimal regardless of the amount of external traffic, even though it does not know this amount a priori. Our analysis utilizes a p
Recently, spatial collaborations and crowdsourcing has emerged as a novel typical pattern for applying to a range of problems. A key problem of spatial collaboration is to allocate suitable workers to nearby tasks in ...
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ISBN:
(纸本)9781450353526
Recently, spatial collaborations and crowdsourcing has emerged as a novel typical pattern for applying to a range of problems. A key problem of spatial collaboration is to allocate suitable workers to nearby tasks in a real-time online way. Traditional crowdsourcing algorithms always consider the quality of worker with prior knowledge. However, in online crowdsourcing context, the quality of crowd-workers is unknown and uncertain. It is so hard for such task crowdsourcing process in an inherently online and dynamic environment. To solve this spatial crowdsourcing problem, the branch-and-bound R-tree data structure is employed in our algorithms to prune the search tree of the nearby crowd-workers. Furthermore, we introduce a new online algorithm to deal with the uncertain crowdsourcing problems. Theoretical analysis and extensive experiments are conducted for validation purpose;and the experimental results show that our algorithms outperform several existing algorithms in terms of computation time in dealing with the increasing number of crowdsourcing task executing candidates.
In this thesis we introduce and evaluate several new models for the analysis of online algorithms. In an online problem, the algorithm does not know the entire input from the beginning; the input is revealed in a sequ...
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In this thesis we introduce and evaluate several new models for the analysis of online algorithms. In an online problem, the algorithm does not know the entire input from the beginning; the input is revealed in a sequence of steps. At each step the algorithm should make its decisions based on the past and without any knowledge about the future. Many important real-life problems such as paging and routing are intrinsically online and thus the design and analysis ofonline algorithms is one of the main research areas in theoretical computer *** analysis is the standard measure for analysis of online algorithms. It has been applied to many online problems in diverse areas ranging from robot navigation, to network routing, to scheduling, to online graph coloring. While in several instances competitive analysis gives satisfactory results, for certain problems it results in unrealistically pessimistic ratios and/orfails to distinguish between algorithms that have vastly differing performance under any practical characterization. Addressing these shortcomings has been the subject of intense research by many of the best minds in the field. In this thesis, building upon recent advances of others we introduce some new models for analysis of online algorithms, namely Bijective Analysis, Average Analysis,Parameterized Analysis, and Relative Interval Analysis. We show that they lead to good results when applied to paging and list update algorithms. Paging and list update are two well known online problems. Paging is one of the main examples of poor behavior of competitive analysis. We show that LRU is the unique optimal online paging algorithm according to Average Analysis on sequences with locality of reference. Recall that in practice input sequences for paging havehigh locality of reference. It has been empirically long established that LRU is the best paging algorithm. Yet, Average Analysis is the first model that gives strict separation of LRU from all other
Uncertainty plays a critical role in many real world applications where the decision maker is faced with multiple alternatives with different costs. These decisions arise in our daily lives, such as whether to rent an...
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ISBN:
(纸本)9781450375184
Uncertainty plays a critical role in many real world applications where the decision maker is faced with multiple alternatives with different costs. These decisions arise in our daily lives, such as whether to rent an apartment or buy a house, which cannot be answered reliably without knowledge of the future. These decisionmaking problems are usually modeled as online rent-or-buy problems, such as the classical ski rental problem [4, 5, 8]. Two paradigms have been widely studied to deal with such uncertainty. On the one hand, online algorithms are designed without prior knowledge to the problem, and competitive ratio (CR) is used to characterize the goodness of the algorithm in lack of the future. On the other hand, machine learning is applied to address uncertainty by making future predictions via building robust models on prior data.
We solve an open problem in the literature by providing an online algorithm for multidimensional bin packing that uses only bounded space. To achieve this, we introduce a new technique for classifying the items to be ...
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We solve an open problem in the literature by providing an online algorithm for multidimensional bin packing that uses only bounded space. To achieve this, we introduce a new technique for classifying the items to be packed. We show that our algorithm is optimal among bounded space algorithms for any dimension d > 1. Its asymptotic performance ratio is (Pi(infinity))(d), where Pi(infinity) approximate to 1.691 is the asymptotic performance ratio of the one-dimensional algorithm Harmonic. A modified version of this algorithm for the case where all items are hypercubes is also shown to be optimal. Its asymptotic performance ratio is sublinear in d. Furthermore, we extend the techniques used in these algorithms to give optimal algorithms for online bounded space variable-sized packing and resource augmented packing.
The design and analysis of randomized on-line algorithms are studied. This problem is shown to be closely related to the synthesis of random walks on graphs with positive real costs on their edges. A theory is develop...
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The design and analysis of randomized on-line algorithms are studied. This problem is shown to be closely related to the synthesis of random walks on graphs with positive real costs on their edges. A theory is developed for the synthesis of such walks, and it is employed to design competitive on-line algorithms.
In the sequential setting, a decades-old fundamental result in online algorithms states that if there is a c-competitive randomized online algorithm against an adaptive, offline adversary, then there is a c-competitiv...
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In the sequential setting, a decades-old fundamental result in online algorithms states that if there is a c-competitive randomized online algorithm against an adaptive, offline adversary, then there is a c-competitive deterministic algorithm. The adaptive, offline adversary is the strongest adversary among the ones usually considered, so the result states that if one has to be competitive against such a strong adversary, then randomization does not help. This implies that researchers do not consider randomization against an adaptive, offline adversary. We prove that in a distributed setting, this result does not necessarily hold, so randomization against an adaptive, offline adversary becomes interesting again. (C) 2020 Elsevier B.V. All rights reserved.
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