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Articles 2461 - 2490 of 3436

Full-Text Articles in Physical Sciences and Mathematics

Measurement And Evaluation Of Blade Passage Frequency Fluctuations (A), Cole V. Duke, Scott D. Sommerfeldt, Kent L. Gee, Connor R. Duke Nov 2007

Measurement And Evaluation Of Blade Passage Frequency Fluctuations (A), Cole V. Duke, Scott D. Sommerfeldt, Kent L. Gee, Connor R. Duke

Faculty Publications

In the active control of tonal noise from cooling fans, one factor that can limit the achievable attenuation is fluctuation of the blade passage frequency in time. Large fluctuations in a short time can hinder the algorithm from converging to the optimal solution. Some fans have steadier speeds than others, which can be due to unsteady driving mechanisms or the physical structure of the fan. Environmental effects, such as back pressure and unsteady blade loading, can also cause the fan speed to fluctuate. The shifting in the blade passage frequency will be measured using a zero-crossing technique to track the …

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Analyzing Gene Relationships For Down Syndrome With Labeled Transition Graphs, Hyrum Carroll, Mark J. Clement, Eric G. Mercer, Neha Rungta, Quinn O. Snell, Randall J. Roper Nov 2007

Analyzing Gene Relationships For Down Syndrome With Labeled Transition Graphs, Hyrum Carroll, Mark J. Clement, Eric G. Mercer, Neha Rungta, Quinn O. Snell, Randall J. Roper

Faculty Publications

The relationship between changes in gene expression and physical characteristics associated with Down syndrome is not well understood. Chromosome 21 genes interact with nonchromosome 21 genes to produce Down syndrome characteristics. This indirect influence, however, is difficult to empirically define due to the number, size, and complexity of the involved gene regulatory networks. This work links chromosome 21 genes to non-chromosome 21 genes known to interact in a Down syndrome phenotype through a reachability analysis of labeled transition graphs extracted from published gene regulatory network databases. The analysis provides new relations in a recently discovered link between a specific gene …

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Intersection Algorithms Based On Geometric Intervals, Nicholas Stewart North Oct 2007

Intersection Algorithms Based On Geometric Intervals, Nicholas Stewart North

Theses and Dissertations

This thesis introduces new algorithms for solving curve/curve and ray/surface intersections. These algorithms introduce the concept of a geometric interval to extend the technique of Bézier clipping. A geometric interval is used to tightly bound a curve or surface or to contain a point on a curve or surface. Our algorithms retain the desirable characteristics of the Bézier clipping technique such as ease of implementation and the guarantee that all intersections over a given interval will be found. However, these new algorithms generally exhibit cubic convergence, improving on the observed quadratic convergence rate of Bézier clipping. This is achieved without …

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Accounting For Additional Heterogeneity: A Theoretic Extension Of An Extant Economic Model, Bradley John Barney Oct 2007

Accounting For Additional Heterogeneity: A Theoretic Extension Of An Extant Economic Model, Bradley John Barney

Theses and Dissertations

The assumption in economics of a representative agent is often made. However, it is a very rigid assumption. Hall and Jones (2004b) presented an economic model that essentially provided for a representative agent for each age group in determining the group's health level function. Our work seeks to extend their theoretical version of the model by allowing for two representative agents for each age—one for each of “Healthy” and “Sick” risk-factor groups—to allow for additional heterogeneity in the populace. The approach to include even more risk-factor groups is also briefly discussed. While our “extended” theoretical model is not applied directly …

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Applying Bayesian Ordinal Regression To Icap Maladaptive Behavior Subscales, Edward P. Johnson Oct 2007

Applying Bayesian Ordinal Regression To Icap Maladaptive Behavior Subscales, Edward P. Johnson

Theses and Dissertations

This paper develops a Bayesian ordinal regression model for the maladaptive subscales of the Inventory for Client and Agency Planning (ICAP). Because the maladaptive behavior section of the ICAP contains ordinal data, current analysis strategies combine all the subscales into three indices, making the data more interval in nature. Regular MANOVA tools are subsequently used to create a regression model for these indices. This paper uses ordinal regression to analyze each original scale separately. The sample consists of applicants for aid from Utah's Division of Services for Persons with Disabilities. Each applicant fills out the Scales of Independent Behavior"”Revised (SIB-R) …

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Heuristic Weighted Voting, Kristine Perry Monteith Oct 2007

Heuristic Weighted Voting, Kristine Perry Monteith

Theses and Dissertations

Selecting an effective method for combining the votes of classifiers in an ensemble can have a significant impact on the overall classification accuracy an ensemble is able to achieve. With some methods, the ensemble cannot even achieve as high a classification accuracy as the most accurate individual classifying component. To address this issue, we present the strategy of Heuristic Weighted Voting, a technique that uses heuristics to determine the confidence that a classifier has in its predictions on an instance by instance basis. Using these heuristics to weight the votes in an ensemble results in an overall average increase in …

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Error Sensor Placement For Active Control Of An Axial Cooling Fan, Benjamin M. Shafer Oct 2007

Error Sensor Placement For Active Control Of An Axial Cooling Fan, Benjamin M. Shafer

Theses and Dissertations

Recent experimental achievements in active noise control (ANC) for cooling fans have used near-field error sensors whose locations are determined according to a theoretical condition of minimized sound power. A theoretical point source model, based on the condition previously stated, reveals the location of near-field pressure nulls that may be used to optimize error sensor placement. The actual locations of these near-field pressure nulls for both an axial cooling fan and a monopole loudspeaker were measured over a two-dimensional grid with a linear array of microphones. The achieved global attenuation for each case is measured over a hemisphere located in …

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Spilling: Expanding Hand Held Interaction To Touch Table Displays, Jeffrey Clement, Dan R. Olsen Jr., Aaron Pace Oct 2007

Spilling: Expanding Hand Held Interaction To Touch Table Displays, Jeffrey Clement, Dan R. Olsen Jr., Aaron Pace

Faculty Publications

We envision a nomadic model of interaction where the personal computer fits in your pocket. Such a computer is extremely limited in screen space. A technique is described for “spilling” the display of a hand held computer onto a much larger table top display surface. Because our model of nomadic computing frequently involves the use of untrusted display services we restrict interactive input to the hand held. Navigation techniques such as scrolling or turning the display can be expressed through the table top. The orientation and position of the hand held on the table top is detected using three conductive …

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Adtrees For Sequential Data And N-Gram Counting, Robert Van Dam, Dan A. Ventura Oct 2007

Adtrees For Sequential Data And N-Gram Counting, Robert Van Dam, Dan A. Ventura

Faculty Publications

We consider the problem of efficiently storing n-gram counts for large n over very large corpora. In such cases, the efficient storage of sufficient statistics can have a dramatic impact on system performance. One popular model for storing such data derived from tabular data sets with many attributes is the ADtree. Here, we adapt the ADtree to benefit from the sequential structure of corpora-type data. We demonstrate the usefulness of our approach on a portion of the well-known Wall Street Journal corpus from the Penn Treebank and show that our approach is exponentially more efficient than the naïve approach to …

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A Data-Dependent Distance Measure For Transductive Instance-Based Learning, Jared Lundell, Dan A. Ventura Oct 2007

A Data-Dependent Distance Measure For Transductive Instance-Based Learning, Jared Lundell, Dan A. Ventura

Faculty Publications

We consider learning in a transductive setting using instance-based learning (k-NN) and present a method for constructing a data-dependent distance “metric” using both labeled training data as well as available unlabeled data (that is to be classified by the model). This new data-driven measure of distance is empirically studied in the context of various instance-based models and is shown to reduce error (compared to traditional models) under certain learning conditions. Generalizations and improvements are suggested.

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Robust Multi-Modal Biometric Fusion Via Multiple Svms, Jonathan Dinerstein, Sabra Dinerstein, Dan A. Ventura Oct 2007

Robust Multi-Modal Biometric Fusion Via Multiple Svms, Jonathan Dinerstein, Sabra Dinerstein, Dan A. Ventura

Faculty Publications

Existing learning-based multi-modal biometric fusion techniques typically employ a single static Support Vector Machine (SVM). This type of fusion improves the accuracy of biometric classification, but it also has serious limitations because it is based on the assumptions that the set of biometric classifiers to be fused is local, static, and complete. We present a novel multi-SVM approach to multi-modal biometric fusion that addresses the limitations of existing fusion techniques and show empirically that our approach retains good classification accuracy even when some of the biometric modalities are unavailable.

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Ecological Interfaces For Improving Mobile Robot Teleoperation, Michael A. Goodrich, Curtis W. Nielsen, Robert W. Ricks Oct 2007

Ecological Interfaces For Improving Mobile Robot Teleoperation, Michael A. Goodrich, Curtis W. Nielsen, Robert W. Ricks

Faculty Publications

Navigation is an essential element of many remote robot operations including search and rescue, reconnaissance, and space exploration. Previous reports on using remote mobile robots suggest that navigation is difficult due to poor situation awareness. It has been recommended by experts in human–robot interaction that interfaces between humans and robots provide more spatial information and better situational context in order to improve an operator’s situation awareness. This paper presents an ecological interface paradigm that combines video, map, and robotpose information into a 3-D mixed-reality display. The ecological paradigm is validated in planar worlds by comparing it against the standard interface …

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Psoda: Better Tasting And Less Filling Than Paup, Hyrum Carroll, Mark J. Clement, Mark Ebbert, Quinn O. Snell Oct 2007

Psoda: Better Tasting And Less Filling Than Paup, Hyrum Carroll, Mark J. Clement, Mark Ebbert, Quinn O. Snell

Faculty Publications

PSODA is an open-source phylogenetic search application that implements traditional parsimony and likelihood search techniques as well as advanced search algorithms. PSODA is compatible with PAUP and the search algorithms are competitive with those in PAUP. PSODA also adds a basic scripting language to the PAUP block, making it possible to easily create advanced meta-searches. Additionally, PSODA provides a user-friendly GUI with real-time graphing visualizations and phylogeny viewer, and a multiple sequence alignment algorithm PSODA is freely available from the PSODA web site: http://csl.cs.byu.edu/psoda.

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Psodascript: Applying Advanced Language Constructs To Open-Source Phylogenetic Search, Hyrum Carroll, Mark J. Clement, Jonathan Krein, Quinn O. Snell, Adam R. Teichert Oct 2007

Psodascript: Applying Advanced Language Constructs To Open-Source Phylogenetic Search, Hyrum Carroll, Mark J. Clement, Jonathan Krein, Quinn O. Snell, Adam R. Teichert

Faculty Publications

Due to the immensity of phylogenetic tree space for large data sets, researches must rely on heuristic searches to infer reasonable phylogenies. By designing meta-searches which appropriately combine a variety of heuristics and parameter settings, researchers can significantly improve the performance of heuristic searches. Advanced language constructs in the open-source PSODA project—including variables, mathematical and logical expressions, conditional statements, and user-defined commands—give researchers a better framework for the exploration and exploitation of phylogenetic meta-search algorithms. PSODA’s approach to scripting meta-search algorithms is unique among open-source packages and addresses several limitations of other phylogenetic applications.

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Using Parsimony To Guide Maximum Likelihood Searches, Hyrum Carroll, Mark J. Clement, Timothy O'Connor, Quinn O. Snell, Kenneth Sundberg Oct 2007

Using Parsimony To Guide Maximum Likelihood Searches, Hyrum Carroll, Mark J. Clement, Timothy O'Connor, Quinn O. Snell, Kenneth Sundberg

Faculty Publications

The performance of maximum likelihood searches can be boosted by using the most parsimonious tree as a starting point for the search. The time spent in performing the parsimony search to find this starting tree is insignificant compared to the time spent in the maximum likelihood search, leading to an overall gain in search time. These parsimony boosted maximum likelihood searches lead to topologies with scores statisitically similar to the unboosted searches, but in less time.

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Limitations And Extensions Of The Wolf-Phc Algorithm, Philip R. Cook Sep 2007

Limitations And Extensions Of The Wolf-Phc Algorithm, Philip R. Cook

Theses and Dissertations

Policy Hill Climbing (PHC) is a reinforcement learning algorithm that extends Q-learning to learn probabilistic policies for multi-agent games. WoLF-PHC extends PHC with the "win or learn fast" principle. A proof that PHC will diverge in self-play when playing Shapley's game is given, and WoLF-PHC is shown empirically to diverge as well. Various WoLF-PHC based modifications were created, evaluated, and compared in an attempt to obtain convergence to the single shot Nash equilibrium when playing Shapley's game in self-play without using more information than WoLF-PHC uses. Partial Commitment WoLF-PHC (PCWoLF-PHC), which performs best on Shapley's game, is tested on other …

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Using A Mini-Uav To Support Wilderness Search And Rescue: Practices For Human-Robot Teaming, Julie A. Adams, Brian G. Buss, Joseph L. Cooper, Michael A. Goodrich, Curtis Humphrey, Ron Zeeman Sep 2007

Using A Mini-Uav To Support Wilderness Search And Rescue: Practices For Human-Robot Teaming, Julie A. Adams, Brian G. Buss, Joseph L. Cooper, Michael A. Goodrich, Curtis Humphrey, Ron Zeeman

Faculty Publications

Wilderness Search and Rescue can benefit from aerial imagery of the search area. Mini Unmanned Aerial Vehicles can potentially provide such imagery, provided that the autonomy, search algorithms, and operator control unit are designed to support coordinated human-robot search teams. Using results from formal analyses of the WiSAR problem domain, we summarize and discuss information flow requirements for WiSAR with an eye toward the efficient use of mUAVs to support search. We then identify and discuss three different operational paradigms for performing field searches, and identify influences that affect which human-robot team paradigm is best. Since the likely location of …

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A Utile Function Optimizer, James Carroll, Christopher K. Monson, Kevin Seppi Sep 2007

A Utile Function Optimizer, James Carroll, Christopher K. Monson, Kevin Seppi

Faculty Publications

We recast the problem of unconstrained continuous evolutionary optimization as inference in a fixed graphical model. This approach allows us to address several pervasive issues in optimization, including the traditionally difficult problem of selecting an algorithm that is most appropriate for a given task. This is accomplished by placing a prior distribution over the expected class of functions, then employing inference and intuitively defined utilities and costs to transform the evolutionary optimization problem into one of active sampling. This allows us to pose an approach to optimization that is optimal for each expressly stated function class. The resulting solution methodology …

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Parallel Pso Using Mapreduce, Andrew Mcnabb, Christopher K. Monson, Kevin Seppi Sep 2007

Parallel Pso Using Mapreduce, Andrew Mcnabb, Christopher K. Monson, Kevin Seppi

Faculty Publications

In optimization problems involving large amounts of data, such as web content, commercial transaction information, or bioinformatics data, individual function evaluations may take minutes or even hours. Particle Swarm Optimization (PSO) must be parallelized for such functions. However, large-scale parallel programs must communicate efficiently, balance work across all processors, and address problems such as failed nodes. We present MapReduce Particle Swarm Optimization (MRPSO), a PSO implementation based on the MapReduce parallel programming model. We describe MapReduce and show how PSO can be naturally expressed in this model, without explicitly addressing any of the details of parallelization. We present a benchmark …

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Development Of A Method For Calculating Delta Scuti Rotational Velocities And Hydrogen Beta Color Indices, Tabitha Christi Buehler Sep 2007

Development Of A Method For Calculating Delta Scuti Rotational Velocities And Hydrogen Beta Color Indices, Tabitha Christi Buehler

Theses and Dissertations

To add to the understanding of the structure and evolution of Delta Scuti stars, 167 Delta Scutis north of -01 degrees declination and brighter than 13th magnitude have been observed spectroscopically. A method for calculating rotational velocity values and Hydrogen-Beta color indices for the stars in the data set with no previously published values is developed, using the stars in the data set brighter than 7th magnitude. Rotational velocity values for four stars with previously unknown values and Hydrogen-Beta index values for five stars with previously unknown values are calculated.

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Novel Perturbation Approach For The Structure Factor Of The Attractive Hard-Core Yukawa Fluid, Andrij Trokhymchuk, Roman Melnyk, Filip Moucka, Ivo Nezbeda Sep 2007

Novel Perturbation Approach For The Structure Factor Of The Attractive Hard-Core Yukawa Fluid, Andrij Trokhymchuk, Roman Melnyk, Filip Moucka, Ivo Nezbeda

Faculty Publications

A novel perturbation approach for the structure factor S(k) of the Lennard-Jones-type Yukawa fluid with z=1.8 is presented. An approach is based on a new reference system, that is, the short-range Yukawa model with z0 > z=1.8. By choosing for the reference system the value z0=6, it is shown that (i) the proposed approach for S(k) performs much better than the traditional hard-sphere reference perturbation method does; (ii) the use of an approximate mean spherical (MSA) description of the reference structure factor provides the results for S(k) that are more accurate as those obtained from the direct MSA computations; and (iii) …

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Improving Neural Network Classification Training, Michael Edwin Rimer Sep 2007

Improving Neural Network Classification Training, Michael Edwin Rimer

Theses and Dissertations

The following work presents a new set of general methods for improving neural network accuracy on classification tasks, grouped under the label of classification-based methods. The central theme of these approaches is to provide problem representations and error functions that more directly improve classification accuracy than conventional learning and error functions. The CB1 algorithm attempts to maximize classification accuracy by selectively backpropagating error only on misclassified training patterns. CB2 incorporates a sliding error threshold to the CB1 algorithm, interpolating between the behavior of CB1 and standard error backpropagation as training progresses in order to avoid prematurely saturated network weights. CB3 …

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Hardness For Explicit State Software Model Checking Benchmarks, Eric G. Mercer, Neha Rungta Sep 2007

Hardness For Explicit State Software Model Checking Benchmarks, Eric G. Mercer, Neha Rungta

Faculty Publications

Directed model checking algorithms focus computation resources in the error-prone areas of concurrent systems. The algorithms depend on some empirical analysis to report their performance gains. Recent work characterizes the hardness of models used in the analysis as an estimated number of paths in the model that contain an error. This hardness metric is computed using a stateless random walk. We show that this is not a good hardness metric because models labeled hard with a stateless random walk metric have easily discoverable errors with a stateful randomized search. We present an analysis which shows that a hardness metric based …

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Poisson Disk Point Sets By Hierarchical Dart Throwing, David Cline, Parris K. Egbert, Kenric B. White Sep 2007

Poisson Disk Point Sets By Hierarchical Dart Throwing, David Cline, Parris K. Egbert, Kenric B. White

Faculty Publications

Poisson disk point sets are “ideally” generated through a process of dart throwing. The naive dart throwing algorithm is extremely expensive if a maximal set is desired, however. In this paper we present a hierarchical dart throwing procedure which produces point sets that are equivalent to naive dart throwing, but is very fast. The procedure works by intelligently excluding areas known to be fully covered by existing samples. By excluding covered regions, the probability of accepting a thrown dart is greatly increased. Our algorithm is conceptually simple, performs dart throwing in O(N) time and memory, and produces a maximal point …

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Image-Based Color Schemes, Bryan S. Morse, Daniel Thornton, Qing Xia, John Uibel Sep 2007

Image-Based Color Schemes, Bryan S. Morse, Daniel Thornton, Qing Xia, John Uibel

Faculty Publications

This paper presents a novel method for generating color schemes based on images intended to anchor color designs. This has wide applicability for web pages, printed materials, or other applications where images are used as a key part of the overall design. Unlike methods that are variants of color quantization and try to pixel-wise approximate the image, this method draws on graphic-design principles by emphasizing hue selection first, weighting effects of color by saturation, and considering the local spatial coherency in order to determine the overall visual impact of a color. Results demonstrate that the method generalizes to a wide …

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Optimization Of Control Source And Error Sensor Locations In Free Field Active Noise Control, Connor Raymond Duke Aug 2007

Optimization Of Control Source And Error Sensor Locations In Free Field Active Noise Control, Connor Raymond Duke

Theses and Dissertations

Previous work has shown that active noise control (ANC) can be applied to axial cooling fans. Optimization of the control source and error sensor placement is desired to maximize the attenuation using ANC. A genetic algorithm was developed to find the optimal placement of control sources for a given primary source. The optimal configuration of control sources around a single primary source was shown to be a linear arrangement of the sources. This holds true for both two-dimensional as well as three-dimensional configurations. The higher-order radiation of the linear arrangement has also been verified experimentally, but the improvement in the …

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Using Fuzzy-Word Correlation Factors To Compute Document Similarity Based On Phrase Matching, Jun Won Lee, Yiu-Kai D. Ng Aug 2007

Using Fuzzy-Word Correlation Factors To Compute Document Similarity Based On Phrase Matching, Jun Won Lee, Yiu-Kai D. Ng

Faculty Publications

One of the Web information Retrieval (IR) problems these days is to identify redundant information that exist in (replicated) Web documents. These documents can easily be found in several forms, such as documents in different versions, small documents combined with others to form a larger document, etc. As the Web is becoming more and more popular, the number of documents on the Web is increasing on a daily basis, and filtering redundant ones among this huge number of documents becomes a more difficult and an urgent task. As one of the solutions to this problem, we present a new method …

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Development Of A New Ca Ii H And K Spectrophotometric Temperature Index, Kathleen Elizabeth Moncrieff Aug 2007

Development Of A New Ca Ii H And K Spectrophotometric Temperature Index, Kathleen Elizabeth Moncrieff

Theses and Dissertations

We are developing a new spectrophotometric temperature index based on the Ca II H and K lines. Because these lines are present even in very cool stars and because the Ca II H line is blended with the H-epsilon line in hot stars, this index should cover a very broad range of spectral types. Our data set consisted of 95 stars with spectral types ranging from O9 to M1. We examined five different indices based on the Ca II H + H-epsilon and K lines, as well as single-wavelength indices centered on each of the H-delta and H-gamma lines, which …

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Ontology Aware Software Service Agents: Meeting Ordinary User Needs On The Semantic Web, Muhammed Jassem Al Muhammed Aug 2007

Ontology Aware Software Service Agents: Meeting Ordinary User Needs On The Semantic Web, Muhammed Jassem Al Muhammed

Theses and Dissertations

To achieve the dream of the semantic web, it must be possible for ordinary users to invoke services. It is clear that users need simple-to-invoke-and-use services. This dissertation offers an ontological approach to declaratively create services that users can invoke using free-form, natural-language-like specifications. Our approach uses task ontologies as foundational knowledge. A task ontology consists of a domain ontology and a process ontology. The domain ontology encodes domain information such as possible constraints and instances in terms of object sets, relationship sets among these object sets, and operations over values in object sets and relationship sets. The process ontology …

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Constructing Subdivision Rules From Rational Maps, J. W. Cannon, W. J. Floyd, W. R. Parry Aug 2007

Constructing Subdivision Rules From Rational Maps, J. W. Cannon, W. J. Floyd, W. R. Parry

Faculty Publications

This paper deepens the connections between critically finite rational maps and finite subdivision rules. The main theorem is that if f is a critically finite rational map with no periodic critical points, then for any sufficiently large integer n the iterate f is the subdivision map of a finite subdivision rule. This enables one to give essentially combinatorial models for the dynamics of such iterates.

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