A selective introduction to the field of information-based complexity is presented in the context of the question raised in the title. After introducing some of the basic ideas of this relatively new area that interfa...
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A selective introduction to the field of information-based complexity is presented in the context of the question raised in the title. After introducing some of the basic ideas of this relatively new area that interfaces mathematics and theoretical computer science, the article surveys results on the existence of linear optimal algorithms for linear problems. Several illustrative examples are given along with an indication of the variety of disciplines in which techniques of information-based complexity are being applied.
For system identification problems with stochastic noise, maximum likelihood estimators are frequently used. If noise is deterministic, worst case optimal algorithms should be considered. In this paper we study the fo...
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For system identification problems with stochastic noise, maximum likelihood estimators are frequently used. If noise is deterministic, worst case optimal algorithms should be considered. In this paper we study the following problem: Under what circumstances are maximum likelihood estimators optimal in the worst case?
This paper discusses a problem of searching for and capturing a fugitive by a team of searchers in an N×Ngrid<span style="display: inline-block; position: relative; width: 1.489em; he
We study the K-armed contextual dueling bandit problem, a sequential decision making setting in which the learner uses contextual information to make two decisions, but only observes preference-based feedback suggesti...
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We study the K-armed contextual dueling bandit problem, a sequential decision making setting in which the learner uses contextual information to make two decisions, but only observes preference-based feedback suggesting that one decision was better than the other. We focus on the regret minimization problem under realizability, where the feedback is generated by a pairwise preference matrix that is well-specified by a given function class F. We provide a new algorithm that achieves the optimal regret rate for a new notion of best response regret, which is a strictly stronger performance measure than those considered in prior works. The algorithm is also computationally efficient, running in polynomial time assuming access to an online oracle for square loss regression over F. This resolves an open problem of Dudik et al. (2015) on oracle efficient, regret-optimal algorithms for contextual dueling bandits.
In this paper, we study the problem of replica placement in tree networks subject to server capacity and distance constraints. The client requests are known beforehand, while the number and location of the servers are...
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ISBN:
(纸本)9781467309752
In this paper, we study the problem of replica placement in tree networks subject to server capacity and distance constraints. The client requests are known beforehand, while the number and location of the servers are to be determined. The Single policy enforces that all requests of a client are served by a single server in the tree, while in the Multiple policy, the requests of a given client can be processed by multiple servers, thus distributing the processing of requests over the platform. For the Single policy, we prove that all instances of the problem are NP-hard, and we propose approximation algorithms. The problem with the Multiple policy was known to be NP-hard with distance constraints, but we provide a polynomial time optimal algorithm to solve the problem in the particular case of binary trees when no request exceeds the server capacity.
We seek to minimize the mean-squared deviation of a waiting time function from a desired response function over the class of waiting time functions satisfying the Kleinrock-Nilsson necessary conditions. We will charac...
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We seek to minimize the mean-squared deviation of a waiting time function from a desired response function over the class of waiting time functions satisfying the Kleinrock-Nilsson necessary conditions. We will characterize analytically the optimal policy as the minimum majorant in the appropriate class of the cumulative response to go. We will show that, in general, the monotonicity necessary condition results in optimal policies which depend in some sense on the future and are anticipating.
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.
We give highly efficient algorithms, and almost matching lower bounds, for a range of basic statistical problems that involve testing and estimating the L_1 (total variation) distance between two k-modal distributions...
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ISBN:
(纸本)9781611972511
We give highly efficient algorithms, and almost matching lower bounds, for a range of basic statistical problems that involve testing and estimating the L_1 (total variation) distance between two k-modal distributions p and q over the discrete domain {1,..., n}. More precisely, we consider the following four problems: given sample access to an unknown k-modal distribution p, TESTING IDENTITY TO A KNOWN OR UNKNOWN DISTRIBUTION: 1. Determine whether p = q (for an explicitly given k- modal distribution q) versus p is ε-far from q; 2. Determine whether p = q (where q is available via sample access) versus p is ε-far from q; ESTIMATING L_1 DISTANCE ("TOLERANT TESTING") AGAINST A KNOWN OR UNKNOWN DISTRIBUTION: 3. Approximate d_(TV) (p, q) to within additive ∈ where q is an explicitly given k-modal distribution q; 4. Approximate d_(TV) (p, q) to within additive ∈ where q is available via sample access.
Linear arrays are characterized by a small communication bandwidth and a large communication diameter rendering them unsuited to the implementation of global computations. This paper presents efficient data movement a...
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Linear arrays are characterized by a small communication bandwidth and a large communication diameter rendering them unsuited to the implementation of global computations. This paper presents efficient data movement and partitioning techniques to overcome several shortcomings of linear arrays. These techniques are used to derive optimal parallel algorithms for several geometric problems on n x n images using a fixed-size linear array with p processors, where 1 less-than-or-equal-to p less-than-or-equal-to n. O(n2/p) time solutions are presented for labeling connected image regions, computing the convex hull of each region, and computing nearest neighbors. Consequently, a linear array with n processors can solve several image problems in O(n) time which is the same time taken by a two dimensional mesh-connected computer with n2 processors. Limitations of linear arrays are analyzed by presenting a class of image problems which can be solved sequentially in O(n2) time, but require OMEGA-(n2) time on a linear array, irrespective of the number of processors used and the partitioning of the input image among the processors. An alternate communication-efficient fixed-size organization with p processors is proposed to solve such problems in O(n2/p) time, for 1 less-than-or-equal-to p less-than-or-equal-to n.
A family of intervals on the real line provides a natural model for a vast number of scheduling and VLSI problems. Recently, a number of parallel algorithms to solve a variety of practical problems on such a family of...
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A family of intervals on the real line provides a natural model for a vast number of scheduling and VLSI problems. Recently, a number of parallel algorithms to solve a variety of practical problems on such a family of intervals have been proposed in the literature. We develop computational tools and show how they can be used for the purpose of devising cost-optimal parallel algorithms for a number of interval-related problems including finding a largest subset of pairwise nonoverlapping intervals, a minimum dominating subset of intervals, along with algorithms to compute the shortest path between a pair of intervals and, based on the shortest path, a parallel algorithm to find the center of the family of intervals. More precisely, with an arbitrary family of n intervals as input, all our algorithms run in O(log n) time using O(n) processors in the EREW-PRAM model of computation.
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