Labeled graphs are graphs in which each node and edge has a label. The distance between two labeled graphs is considered to be the weighted sum of the costs of edit operations (insert, delete, and relabel the nodes an...
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Labeled graphs are graphs in which each node and edge has a label. The distance between two labeled graphs is considered to be the weighted sum of the costs of edit operations (insert, delete, and relabel the nodes and edges) to transform one graph to the other. The paper considers two variants of the approximate graph matching problem (AGM): Given a pattern graph P and a data graph D: 1. What is the distance between P and D? 2. What is the minimum distance between P and D when subgraphs can be freely removed from D? We first show that no efficient algorithm can solve either variant of the AGM unless P = NP. Then we present several heuristic algorithms leading to approximate solutions. The heuristics are based on probabilistic hill climbing and maximum flow techniques. Our experimental results involving the comparison of real and simulated data demonstrate the good performance of the algorithms presented.
Corner Stitching was first presented by Ousterhout as a data-structure for VLSI CAD. This paper describes the data-structure in detail. It presents, in greater depth than previously, algorithms for the basic operation...
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Corner Stitching was first presented by Ousterhout as a data-structure for VLSI CAD. This paper describes the data-structure in detail. It presents, in greater depth than previously, algorithms for the basic operations described in Ousterhout's original paper. The algorithms for enumerating and updating arbitrary rectangular areas are new. Their constant space complexity bounds are an improvement over previous algorithms for those operations that were recursive. From a practical standpoint, the elimination of the recursion has also made them much faster.
The article presents methods for the computation of all Mathieu functions of integer order, which cover a large range of n and h;previous algorithms were limited to small values of n. The algorithms are given in suffi...
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The article presents methods for the computation of all Mathieu functions of integer order, which cover a large range of n and h;previous algorithms were limited to small values of n. The algorithms are given in sufficient detail to enable straightforward implementation. The algorithms can handle a large range of the order n (0-200) and the parameter h (0-4 n).
When making decisions under uncertainty, the optimal choices are often difficult to discern, especially if not enough information has been gathered. Two key questions in this regard relate to whether one should stop t...
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When making decisions under uncertainty, the optimal choices are often difficult to discern, especially if not enough information has been gathered. Two key questions in this regard relate to whether one should stop the information gathering process and commit to a decision (stopping criterion), and if not, what information to gather next (selection criterion). In this paper, we show that the recently introduced notion, Same-Decision Probability (SDP), can be useful as both a stopping and a selection criterion, as it can provide additional insight and allow for robust decision making in a variety of scenarios. This query has been shown to be highly intractable, being PPPP-complete, and is exemplary of a class of queries which correspond to the computation of certain expectations. We propose the first exact algorithm for computing the SDP, and demonstrate its effectiveness on several real and synthetic networks. Finally, we present new complexity results, such as the complexity of computing the SDP on models with a Naive Bayes structure. Additionally, we prove that computing the non-myopic value of information is complete for the same complexity class as computing the SDP.
A mobile app for smartphones and tablets to document pressure ulcers was previously developed. The mobile app is part of the rapidly growing field of mobile health. The mobile app replaces paper-based documentation in...
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A mobile app for smartphones and tablets to document pressure ulcers was previously developed. The mobile app is part of the rapidly growing field of mobile health. The mobile app replaces paper-based documentation in a healthcare facility with an electronic record. In a user trial in 2013, a key finding was the high value attributed to wound image (photograph) galleries in the mobile app and wound tracking though graphing progression. Consequently, work was undertaken to enhance the imaging features by developing image analysis algorithms for size and color determination of wounds from wound images taken with an on-board smartphone or tablet camera, using no peripheral hardware or ancillary devices in setting up the image. The reliance solely on the internal smartphone sensors to generate high-accuracy measurements brings novelty to the work and specifically in the field of wound management. The work includes three components. The first component, referred to as mask image, obtains the dimensions of an object in the image. The second component, referred to as camera calibration, reconstructs an image taken on an angle (3-D) referenced back to a 2-D plane. The third algorithm determines the range of colors present in an image, separating the image into three component colors by extracting components from the Red Green Blue format of the image, and converting output to red yellow black. An expert system and/or machine learning is recommended to enhance the correlation of wound color to wound stage.
We consider a packing problem arising in storage management of Video on Demand (VoD) systems. The system consists of a set of video files (movies) and several servers (disks), each having a limited storage capacity, C...
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We consider a packing problem arising in storage management of Video on Demand (VoD) systems. The system consists of a set of video files (movies) and several servers (disks), each having a limited storage capacity, C, and a limited bandwidth (load capacity), L. The goal in the storage allocation problem is to assign the video files to the servers and the bandwidth to the clients. The induced class-constrained packing problem was studied in the past assuming each client provides a single request for a single movie. This paper considers a more general and realistic model-in which each client ranks all the movies in the system. Specifically, for each client j and movie i, it is known how much client j is willing to pay in order to watch movie i. The goal is to maximize the system's profit. Alternatively, the client might provide a ranking of the movies and the goal is to maximize the lexicographic profile of the solution. We prove that the problem is NP-complete and present approximation algorithms and heuristics for systems with a single or multiple disks. For a single disk we present an (1-1/e)-approximation algorithm that is extended for systems with storage costs, and for k-round broadcasting, in which each client might be serviced multiple times. For multiple disks we present a (C-1)(e-1)/Ce-approximation algorithm, two heuristics for determining the storage allocation, and an optimal bandwidth-allocation algorithm. In our simulation of a VoD system, we compared the performance of the suggested heuristics for systems with variable parameters and clients with variable preference distributions. We focused on systems in which client preferences and payment are power-law distributed: a few movies are very popular and clients are willing to pay significantly more for watching them. Our results can be applied to other packing and subset selection problems in which clients provide preferences over the elements.
If V-(m) is an irreducible representation space for the unitary group U(N), then the r-fold tensor product space, is in general reducible. Such a reducible representation can be reduced to a direct sum of irreducible ...
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If V-(m) is an irreducible representation space for the unitary group U(N), then the r-fold tensor product space, is in general reducible. Such a reducible representation can be reduced to a direct sum of irreducible representation spaces, albeit with multiplicity. Clebsch-Gordan coefficients are the overlap coefficients between an orthonormal basis in the tensor product space and an orthonormal basis in the direct sum space. Since such coefficients are basis dependent, bases in the U(N) irrep spaces must be chosen. In this paper we use the Gelfand-Zetlin basis, built out of the chain of subgroups U(N)superset of...superset of U(1). Our first result is to derive algorithms for generating Gelfand-Zetlin bases from Gelfand-Zetlin tableaux. Given these concrete basis realizations we develop algorithms for computing the Clebsch-Gordan coefficients themselves.
We have all heard numerous melodies, whether they come from commercialjingles, jazz ballads, operatic arias, or any of a variety of different sources. How a human detectssimilarities in melodies has been studied exten...
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We have all heard numerous melodies, whether they come from commercialjingles, jazz ballads, operatic arias, or any of a variety of different sources. How a human detectssimilarities in melodies has been studied extensively (Martinez 2001; Hofmann-Engl 2002;Muellensiefen and Frieler 2004). There has also been some effort in modeling melodies so thatsimilarities can be detected algorithmically. Some results in this fascinating study of musicalperception and computation can be found in a collection edited by Hewlett and Selfridge-Field(1998).
The authors cast the algorithm for computing the Z-domain continued fraction expansion by A.M. Davis (1982) in the form of a three-term recurrence relation. Such a recurrence relation processes a mirror image polynomi...
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The authors cast the algorithm for computing the Z-domain continued fraction expansion by A.M. Davis (1982) in the form of a three-term recurrence relation. Such a recurrence relation processes a mirror image polynomial and an anti-mirror image polynomial alternately. The algorithms derived are at least twice as efficient in computational complexity as the algorithms recently proposed by R. Parthasarthy and S.N. Iyer (1987).
This paper proposes algorithms that are invariant to the presence of pulse noise for reconstructing the signals of digital optical images. It shows the results of numerical studies of the proposed and known algorithms...
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This paper proposes algorithms that are invariant to the presence of pulse noise for reconstructing the signals of digital optical images. It shows the results of numerical studies of the proposed and known algorithms, and these results provide evidence of the advantages of the former. An example of the filtering of pulse noise on an image is presented, using the known algorithm and one of the proposed reconstruction algorithms. (C) 2007 Optical Society of America.
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