The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Fenghui Zhang - One of the best experts on this subject based on the ideXlab platform.
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On the effective enumerability of NP problems
Lecture Notes in Computer Science, 2006Co-Authors: Jianer Chen, Iyad A Kanj, Jie Meng, Ge Xia, Fenghui ZhangAbstract:In the field of computational optimization, it is often the case that we are given an instance of an NP problem and asked to enumerate the first few best solutions to the instance. Motivated by this, we propose in this paper a new framework to measure the effective enumerability of NP optimization problems. More specifically, given an instance of an NP problem, we consider the parameterized problem of enumerating a given number of best solutions to the instance, and study its average complexity in terms of the number of solutions. Our framework is different from the previously-proposed ones. For example, although it is known that counting the number of k-paths in a graph is #W[1]-complete, we present a fixed-parameter Enumeration algorithm for the problem. We show that most algorithmic techniques for fixed-parameter tractable problems, such as search trees, color coding, and bounded treewidth, can be used for parameterized Enumerations. In addition, we design elegant and new Enumeration techniques and show how to generate small-size structures and enumerate solutions efficiently.
Iyad A Kanj - One of the best experts on this subject based on the ideXlab platform.
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New Enumeration algorithm for protein structure comparison and classification
BMC Genomics, 2013Co-Authors: Cody Ashby, Daniel Johnson, Karl Walker, Iyad A Kanj, Xiuzhen HuangAbstract:Background Protein structure comparison and classification is an effective method for exploring protein structure-function relations. This problem is computationally challenging. Many different computational approaches for protein structure comparison apply the secondary structure elements (SSEs) representation of protein structures. Results We study the complexity of the protein structure comparison problem based on a mixed-graph model with respect to different computational frameworks. We develop an effective approach for protein structure comparison based on a novel independent set Enumeration algorithm. Our approach (named: ePC, e fficient e numeration-based P rotein structure C omparison) is tested for general purpose protein structure comparison as well as for specific protein examples. Compared with other graph-based approaches for protein structure comparison, the theoretical running-time O (1.47^ rn n ^2) of our approach ePC is significantly better, where n is the smaller number of SSEs of the two proteins, r is a parameter of small value. Conclusion Through the Enumeration algorithm, our approach can identify different substructures from a list of high-scoring solutions of biological interest. Our approach is flexible to conduct protein structure comparison with the SSEs in sequential and non-sequential order as well. Supplementary data of additional testing and the source of ePC will be available at http://bioinformatics.astate.edu/ .
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On the effective enumerability of NP problems
Lecture Notes in Computer Science, 2006Co-Authors: Jianer Chen, Iyad A Kanj, Jie Meng, Ge Xia, Fenghui ZhangAbstract:In the field of computational optimization, it is often the case that we are given an instance of an NP problem and asked to enumerate the first few best solutions to the instance. Motivated by this, we propose in this paper a new framework to measure the effective enumerability of NP optimization problems. More specifically, given an instance of an NP problem, we consider the parameterized problem of enumerating a given number of best solutions to the instance, and study its average complexity in terms of the number of solutions. Our framework is different from the previously-proposed ones. For example, although it is known that counting the number of k-paths in a graph is #W[1]-complete, we present a fixed-parameter Enumeration algorithm for the problem. We show that most algorithmic techniques for fixed-parameter tractable problems, such as search trees, color coding, and bounded treewidth, can be used for parameterized Enumerations. In addition, we design elegant and new Enumeration techniques and show how to generate small-size structures and enumerate solutions efficiently.
Jianer Chen - One of the best experts on this subject based on the ideXlab platform.
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On the effective enumerability of NP problems
Lecture Notes in Computer Science, 2006Co-Authors: Jianer Chen, Iyad A Kanj, Jie Meng, Ge Xia, Fenghui ZhangAbstract:In the field of computational optimization, it is often the case that we are given an instance of an NP problem and asked to enumerate the first few best solutions to the instance. Motivated by this, we propose in this paper a new framework to measure the effective enumerability of NP optimization problems. More specifically, given an instance of an NP problem, we consider the parameterized problem of enumerating a given number of best solutions to the instance, and study its average complexity in terms of the number of solutions. Our framework is different from the previously-proposed ones. For example, although it is known that counting the number of k-paths in a graph is #W[1]-complete, we present a fixed-parameter Enumeration algorithm for the problem. We show that most algorithmic techniques for fixed-parameter tractable problems, such as search trees, color coding, and bounded treewidth, can be used for parameterized Enumerations. In addition, we design elegant and new Enumeration techniques and show how to generate small-size structures and enumerate solutions efficiently.
Derrick G. Watson - One of the best experts on this subject based on the ideXlab platform.
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The role of eye movements in subitizing and counting.
Journal of experimental psychology. Human perception and performance, 2007Co-Authors: Derrick G. Watson, Elizabeth A. Maylor, Lucy A. M. BruceAbstract:Previous work has suggested that eye movements may be necessary for accurate Enumeration beyond the subitization range of about 4 items. This study determined the frequency of eye movements normally made during Enumeration, their relationship to response times, and whether they are required for accurate performance. This was achieved by monitoring eye movements and comparing performance when observers were allowed to saccade and when they were not. The results showed that (a) there was a sharp increase in saccadic frequency beyond about 4 items (from < 0.2 saccades per item to about 1 per item), and (b) Enumeration of fewer than 4 items remained rapid and accurate even when eye movements were prevented, whereas Enumeration beyond this became less efficient and sometimes less accurate. The results are discussed in relation to the memory and processing requirements of Enumeration tasks.
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Aging and Enumeration: a selective deficit for the subitization of targets among distractors
Psychology and Aging, 2002Co-Authors: Derrick G. Watson, Elizabeth A. Maylor, Nicola J. MansonAbstract:The term subitization has been used to refer to the fast and accurate Enumeration of up to about 4 items. Beyond 4 items, Enumeration becomes more serial and less accurate, with each additional item adding to the total Enumeration time. The effects of aging on visual Enumeration of targets (Os) were assessed with and without the presence of distractors (Xs). Young participants (n = 30; 18-27 years) showed the usual subitization-counting Enumeration function, both with and without the presence of distractors. In contrast, for older participants (n = 35; 65-79 years), evidence for subitization was found only when distractors were absent. This occurred even though they could detect an individual target among distractors in parallel across the field. The results are discussed in relation to recent theories of visual selection and Enumeration.
A. Sorbi - One of the best experts on this subject based on the ideXlab platform.
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Quasi-minimal Enumeration degrees and minimal Turing degrees
Annali di Matematica Pura ed Applicata, 1998Co-Authors: Theodore A. Slaman, A. SorbiAbstract:We show that there exists a set A such that A has quasi-minimal Enumeration degree, and there are uncountably many sets B such that A is Enumeration reducible to B and B has minimal Turing degree. Answering a related question raised by Solon, we also show that there exists a nontotal Enumeration degree which is not e-hyperimmune .
