Evolution algorithms for combinatorial optimization have been proposed in the 70's. They did not have a major influence. With the availability of parallel computers, these algorithms will become more important. In...
详细信息
Evolution algorithms for combinatorial optimization have been proposed in the 70's. They did not have a major influence. With the availability of parallel computers, these algorithms will become more important. In this paper we discuss the dynamics of three different classes of evolution algorithms: network algorithms derived from the replicator equation, Darwinian algorithms and genetic algorithms inheriting genetic information. We present a new genetic algorithm which relies on intelligent evolution of individuals. With this algorithm, we have computed the best solution of a famous travelling salesman problem. The algorithm is inherently parallel and shows a superlinear speedup in multiprocessor systems.
The fast Fourier transform (FFT) has been used to devise efficient algorithms in four types of discrete data problems. These are exact inference on multinomial data, several 2 x 2 tables, unstratified and stratified l...
详细信息
The fast Fourier transform (FFT) has been used to devise efficient algorithms in four types of discrete data problems. These are exact inference on multinomial data, several 2 x 2 tables, unstratified and stratified linear logistic models, and multi-way contingency table data. We review these applications. Normally, FFT algorithms are presented in terms of characteristic functions;we do that in terms of polynomials. A polynomial-based approach is simpler and derives naturally from the fact that exact distributions for many discrete data models, including those reviewed, arise from polynomials. This approach, moreover, facilitates a synthesis of diverse algorithms used in the field of exact inference. (C) 1997 Elsevier Science B.V.
The problem of testing a dose-response relationship in the presence of exchangeably correlated binary data has been addressed using a variety of models. Most commonly used approaches are derived from likelihood or gen...
详细信息
The problem of testing a dose-response relationship in the presence of exchangeably correlated binary data has been addressed using a variety of models. Most commonly used approaches are derived from likelihood or generalized estimating equations and rely on large-sample theory to justify their inferences. However, while earlier work has determined that these methods may perform poorly for small or sparse samples, there are few alternatives available to those faced with such data. We propose an exact trend test for exchangeably correlated binary data when groups of correlated observations are ordered. This exact approach is based on an exponential model derived by Molenberghs and Ryan (1999) and Ryan and Molenberghs (1999) and provides natural analogues to Fisher's exact test and the binomial trend test when the data are correlated. We use a graphical method with which one can efficiently compute the exact tail distribution and apply the test to two examples.
In this paper, we investigate the leaderless and the leader-follower coherence of tree-symmetric networks. Firstly, the analytical expressions for the product and the sum of the reciprocals of all nonzero Laplacian ei...
详细信息
In this paper, we investigate the leaderless and the leader-follower coherence of tree-symmetric networks. Firstly, the analytical expressions for the product and the sum of the reciprocals of all nonzero Laplacian eigenvalues of tree-symmetric networks are computed. Secondly, comparing the leaderless and leader-follower coherence, the existence of leader nodes and network parameters have a great impact on the coherence in the noisy environment. Finally, the Laplacian eigenvalues of tree-symmetric networks were utilized to analyze other properties of the network. These research results have certain theoretical significance for the promotion of distributed system and block chain technology.
The neurotoxicity of a substance is often tested using animal bioassays. In the functional observational battery, animals are exposed to a test agent and multiple outcomes are recorded to assess toxicity, using approx...
详细信息
The neurotoxicity of a substance is often tested using animal bioassays. In the functional observational battery, animals are exposed to a test agent and multiple outcomes are recorded to assess toxicity, using approximately 40 animals measured on up to 30 different items. This design gives rise to a challenging statistical problem: a large number of outcomes for a small sample of subjects. We propose an exact test for multiple binary outcomes, under the assumption that the correlation among these items is equal. This test is based upon an exponential model described by Molenberghs and Ryan (1999, Environmetrics 10, 279300) and extends the methods developed by Corcoran et al. (2001, Biometrics 57, 941-948) who developed an exact test for exchangeably correlated binary data for groups (clusters) of correlated observations. We present a method that computes an exact p-value testing for a joint dose-response relationship. An estimate of the parameter for dose response is also determined along with its 95% confidence bound. The method is illustrated using data from a neurotoxicity bioassay for the chemical perchlorethylene.
The wireless networking environment presents formidable challenges to the study of broadcasting and multicasting problems. In this paper we focus on the problem of multicast tree construction, and we introduce and eva...
详细信息
The wireless networking environment presents formidable challenges to the study of broadcasting and multicasting problems. In this paper we focus on the problem of multicast tree construction, and we introduce and evaluate algorithms for tree construction in infrastructureless, all-wireless applications. The performance metric used to evaluate broadcast and multicast trees is energy-efficiency. We develop the Broadcast Incremental Power (BIP) algorithm, and adapt it to multicast operation by introducing the Multicast Incremental Power (MIP) algorithm. These algorithms exploit the broadcast nature of the wireless communication environment, and address the need for energy-efficient operation. We demonstrate that our algorithms provide better performance than algorithms that have been developed for the link-based, wired environment.
Multinomial goodness-of-fit tests arise in a diversity of milieu. The long history of the problem has spawned a multitude of asymptotic tests. If the sample size relative to the number of categories is small, the accu...
详细信息
Multinomial goodness-of-fit tests arise in a diversity of milieu. The long history of the problem has spawned a multitude of asymptotic tests. If the sample size relative to the number of categories is small, the accuracy of these tests is compromised. In that case, an exact test is a prudent option. But such tests are computationally intensive and need efficient algorithms. This paper gives a conceptual overview, and empirical comparisons of two avenues, namely the network and fast Fourier transform (FFT) algorithms, for an exact goodness-of-fit test on a multinomial. We show that a recursive execution of a polynomial product forms the basis of both these approaches. Specific details to implement the network method, and techniques to enhance the efficiency of the FFT algorithm are given. Our empirical comparisons show that For exact analysis with the chi-square and likelihood ratio statistics, the network-cum-polynomial multiplication algorithm is the more efficient and accurate of the two.
We study the problem of the amount of information (advice) about a graph that must be given to its nodes in order to achieve fast distributed computations. The required size of the advice enables to measure the inform...
详细信息
We study the problem of the amount of information (advice) about a graph that must be given to its nodes in order to achieve fast distributed computations. The required size of the advice enables to measure the information sensitivity of a network problem. A problem is information sensitive if little advice is enough to solve the problem rapidly (i.e., much faster than in the absence of any advice), whereas it is information insensitive if it requires giving a lot of information to the nodes in order to ensure fast computation of the solution. In this paper, we study the information sensitivity of distributed graph coloring.
We present a comparison of two efficient algorithms for exact analysis of an unordered 2 x K table. First, by considering conditional generating functions, we show that both the network algorithm of Mehta and Patel (J...
详细信息
We present a comparison of two efficient algorithms for exact analysis of an unordered 2 x K table. First, by considering conditional generating functions, we show that both the network algorithm of Mehta and Patel (J. Amer. Statist. Assoc. 78 (1983)) and the fast Fourier transform (FFT) algorithm of Baglivo et al. (J. Amer. Statist. Assoc. 82 (1992)) rest on the same foundation. This foundation is a recursive polynomial relation, We further show that the network algorithm is equivalent to a stage-wise implementation of this recursion while the FFT algorithm is based on performing the same recursion at complex roots of unity. Our empirical results for the Pearson X(2), likelihood ratio, and Freeman-Halton statistics show that the network algorithm, or equivalently, the recursive polynomial multiplication algorithm is superior to the FFT algorithm with respect to computing speed and accuracy.
Yao and Tritchler (1993, Biometrics 49, 233-236) proposed an exact test for conditional independence in a series of 2 x 2 tables, and presented a fast Fourier transform (FFT) algorithm to compute exact significance le...
详细信息
Yao and Tritchler (1993, Biometrics 49, 233-236) proposed an exact test for conditional independence in a series of 2 x 2 tables, and presented a fast Fourier transform (FFT) algorithm to compute exact significance levels for it. The purpose of this note is to provide a general perspective on computational methods applicable to this problem. We also assess the power and efficiency comparisons done by them.
暂无评论