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Dehaven, Ryan Swords. "Smarter NEAT Nets." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1024.
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This paper discusses a modification to improve usability and functionality of a ge- netic neural net algorithm called NEAT (NeuroEvolution of Augmenting Topolo- gies). The modification aims to accomplish its goal by automatically changing parameters used by the algorithm with little input from a user. The advan- tage of the modification is to reduce the guesswork needed to setup a successful experiment with NEAT that produces a usable Artificial Intelligence (AI). The modified algorithm is tested against the unmodified NEAT with several different setups and the results are discussed. The algorithm shows strengths in some areas but can increase the runtime of NEAT due to the addition of parameters into the solution search space.
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Bowden, Fred D. J. "The modelling and analysis of command and control decision processes using extended time petri nets." Title page, table of contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phb784.pdf.
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Bibliography: leaves 177-191. This thesis uses a new type of extended time Petri net to model and analyse command and control decision processes. A comprehensive review of existing time Petri net structures is given. This concludes with the introduction of time Petri net structure that incorporates the most commonly used time structures. This extended time Petri net structure is then used in the definition of the basic modelling blocks required to model command and control decision processes. This basic modelling block forms the basis of the direct analysis techniques that are introduced in the thesis.
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Alexiev, Vladimir. "Non-deterministic interaction nets." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0021/NQ46797.pdf.
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Jin, Wei. "Petri nets and their applications." Virtual Press, 1991. http://liblink.bsu.edu/uhtbin/catkey/774753.
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Petri nets are named in honor of Dr. Carl A. Petri for his famous Ph.D dissertation of general net theory in 1962. A substantial amount of work utilizing and modifying the Petri nets has been done since then, and they have turned out to be very useful in the study of asynchronous concurrent systems. The liveness and reachability problems are considered to be some of the major problems in Petri net theory.Since the structure of a Petri net can be regarded as sets of places and transitions form a graphical point of view, this thesis is concerned with utilizing the results of graph theory to investigate the liveness in terms of deadlock problems of a special subclass of Petri nets, free-choice Petri nets. As a subclass of Petri nets, the class of free-choice Petri nets possesse relatively strong analysis properties. This is especially true of complete free-choice Petri nets. We show in particular that any system which can be modeled by a general Petri net can also be modeled by a free-choice Petri net.Department of Computer Science
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Dahlbom, Anders. "Petri nets for situation recognition." Doctoral thesis, Örebro universitet, Akademin för naturvetenskap och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-13089.
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Situation recognition is a process with the goal of identifying a priori defined situations in a flow of data and information. The purpose is to aid decision makers with focusing on relevant information by filtering out situations of interest. This is an increasingly important and non trivial problem to solve since the amount of information in various decision making situations constantly grow. Situation recognition thus addresses the information gap, i.e. the problem of finding the correct information at the correct time. Interesting situations may also evolve over time and they may consist of multiple participating objects and their actions. This makes the problem even more complex to solve. This thesis explores situation recognition and provides a conceptualization and a definition of the problem, which allow for situations of partial temporal definition to be described. The thesis then focuses on investigating how Petri nets can be used for recognising situations. Existing Petri net based approaches for recognition have some limitations when it comes to fulfilling requirements that can be put on solutions to the situation recognition problem. An extended Petri net based technique that addresses these limitations is therefore introduced. It is shown that this technique can be as efficient as a rule based techniques using the Rete algorithm with extensions for explicitly representing temporal constraints. Such techniques are known to be efficient; hence, the Petri net based technique is efficient too. The thesis also looks at the problem of learning Petri net situation templates using genetic algorithms. Results points towards complex dynamic genome representations as being more suited for learning complex concepts, since these allow for promising solutions to be found more quickly compared with classical bit string based representations. In conclusion, the extended Petri net based technique is argued to offer a viable approach for situation recognition since it: (1) can achieve good recognition performance, (2) is efficient with respect to time, (3) allows for manually constructed situation templates to be improved and (4) can be used with real world data to find real world situations.Anders Dahlbom is also affiliated to Skövde Artificial Intelligence Lab (SAIL), Information Fusion Research Program, Högskolan i Skövde
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David, Nicolas. "Discrete Parameters in Petri Nets." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4108/document.
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Afin de permettre une modélisation plus souple des systèmes, nous proposons d’étendre les réseaux de Petri par des paramètres discrets représentant le poids des arcs ou le nombre de jetons présents dans les places. Dans ce modèle, tout problème de décision peut être décliné sous deux versions, une universelle, demandant si la propriété considérée est vraie quelles que soient les valeurs que prennent les paramètres et une existentielle, qui s’interroge sur l’existence d’une valeur pour les paramètres telle que la propriété soit satisfaite. Concernant la couverture, nous montrons que ces deux problèmes sont indécidables dans le cas général. Nous introduisons donc des sous classes syntaxiques basées sur la restriction des paramètres aux places, aux arcs en sortie ou aux arcs en entrée des transitions. Dans ces différents cas, nous montrons que la couverture existentielle et universelle sont décidables et EXPSPACE-complètes. Nous étudions alors le problème de la synthèse de paramètres qui s’intéresse à calculer l’ensemble des valeurs de paramètres telles que la propriété considérée soit vraie. Sur les sous classes introduites, concernant la couverture, nous montrons que les ensembles solutions à la synthèse ont des structures fermée supérieurement (cas des arcs de sortie) et fermée inférieurement (cas des arcs d’entrée). Nous prouvons alors que ces ensembles se calculent par un algorithme de la littérature, proposé par Valk et Jantzen, dont les conditions d’application se réduisent aux problèmes de décision étudiés précédemment. Enfin nous étudions les frontières de décision en nous intéressant aux versions paramétrées de l’accessibilité pour ces sous classesWith the aim of increasing the modelling capability of Petri nets, we suggest that models involve parameters to represent the weights of arcs, or the number of tokens in places. We consider the property of coverability of markings. Two general questions arise, the universal and the existential one: “Is there a parameter value for which the property is satisfied?” and “Does the property hold for all possible values of the parameters”. We show that these issues are undecidable in the general case. Therefore, we also define subclasses of parameterised nets, depending on whether the parameters are used on places, input or output arcs of transitions. For some classes, we prove that universal and existential coverability become decidable, making these classes more usable in practice. To complete this study, we prove that those problems are EXPSPACE-complete. We also address a problem of parameter synthesis, that is computing the set of values for the parameters such that a given marking is coverable in the instantiated net. Restricting parameters to only input weights (preT-PPNs) provides a downward-closed structure to the solution set. We therefore invoke a result for the representation of upward closed set from Valk and Jantzen. The condition to use this procedure is equivalent to decide the universal coverability. We also propose an adaptation of this reasoning to the case of parameters used only as output weights (postT-PPNs). In this case, the condition to use this procedure can be reduced to the decidability of the existential coverability. Finally, we broaden this study by establishing decision frontiers through the study of existential and universal reachability
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Tranquilli, Paolo. "Nets between determinism and nondeterminism." Paris 7, 2009. http://www.theses.fr/2009PA077033.
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Cette thèse de théorie de la démonstration étudie les propriétés de la syntaxe parallèle de la logique linéaire (LL) de Girard, les réseaux de preuve. La première partie présente le terrain commun sur lequel s'appuient les parties suivantes. En particulier, le paradigme des réseaux d'interaction de Lafont est utilisé pour présenter les principaux objets de recherche de la thèse : d'un côté, les réseaux de preuve de Hughes et van Glabbeek pour la logique linéaire multiplicative additive (MAIL) ; de l'autre, les réseaux différentiels d'Ehrhard et Régnier pour la logique linéaire différentielle (DiLL) obtenue en ajoutant des opérateurs différentiels à LL multiplicative exponentielle. Dans la deuxième partie, nous nous concentrons sur MALL, en étudiant ses relations avec la sémantique dénotationnelle des espace hypercohérents d'Ehrhard. Un critère est établi sur les réseaux de preuve de MALL caractérisant ceux interprétés (par la notion d'expérience de Girard) comme des hypercliques, c'est-à-dire des objets des espaces hypercohérents. On montre ensuite la stabilité de ce critère par réduction des coupures. Dans la troisième partie, nous passons à DiLL. Nous prouvons la confluence des réseaux purs de DiLL en utilisant un résultat de développements finis. Ensuite, nous montrons un théorème correspondant à la standardisation de LL (récemment prouvé par Pagani et Tortora de Falco), à partir duquel la normalisation forte du cas simplement typé peut être déduite. Enfin, nous présentons une version du lambda-calcul avec ressources de Boudol, ainsi qu'une traduction de celle-ci dans les réseaux intuitionnistes de DiLL. Cette traduction permet de prouver la confluence de ce calculThis thesis in proof theory studies the properties of the parallel syntax of Girard's Linear Logic, proof nets. In the first part the common ground on which the later parts stand is presented. In particular Lafont's interaction net paradigm is used to present the main objects of research of the work: on one side Hughes and van Glabbeek's proof nets for multiplicative additive linear logic (MALL), on the other Ehrhard and Regnier's differential nets, the proof nets for differential linear logic (DiLL), obtained by adding differential operators to the ones of multiplicative exponential linear logic. In the second part we concentrate on MALL, studying its relationship with Ehrhard hypercoherent denotational semantics. A criterion is established on MALL nets characterizing those that are interpreted (via Girard's notion of experiment) as states jn this semantics. This criterion is also shown to be stable under cut reduction. In the third part we pass to DiLL. We prove confluence of pure DiLL nets via a result of finite developments. Then we show a theorem corresponding to the standardization one for LL (only recently proved by Pagani and Tortora de Falco), from which strong normalization in the simply typed case can be deduced. Finally a version of Boudol's lambda calculus with resources is introduced together with a translation from it to DiLL intuitionistic nets. This translation permits to prove confluence for such calculus
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Laws, Marguerite Carey. "Joyce's Nets as Semiotic Systems." W&M ScholarWorks, 1991. https://scholarworks.wm.edu/etd/1539625671.
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Guerrieri, Giulio. "Differential nets experiments and reduction." Paris 7, 2013. http://www.theses.fr/2013PA077119.
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Sous la direction de M. Tortora de Falco (Université Roma Tre) et M. Ehrhard (Université Paris Diderot - Paris 7), mes recherches de thèse portent principalement sur deux thèmes : 1) la logique linéaire, notamment sa version différentielle, où mes contributions principales sont l'introduction d'une syntaxe non-inductive (c'est-à-dire « plus géométrique ») pour les réseaux de la logique linéaire (différentielle) multiplicative et exponentielle et l'étude du lien entre expériences de la sémantique relationnelle et développement de Taylor d'un réseau de la logique linéaire, ce qui mène a une simplification de la démonstration de l'injectivité de la sémantique relationnelle dans le cas des réseaux acycliques et connexes ; 2) le lambda-calcul par valeur étudié du point de vue de la logique linéaire, où mes principales contributions sont l'étude de la bêta-réduction par valeur (et des certaines machines abstraites qui l'implémentent) et la définition d'une extension de la bêta-réduction par valeur induite par la traduction « ennuyeuse » de Girard des lambda-termes dans les réseaux de la logique linéaire multiplicative et exponentielleSupervised by Prof. Tortora de Falco (Universita Roma Tre) and Prof. Ehrhard (Université Paris Diderot - Paris 7), my thesis research is focused mainly on two topics: 1) linear logic, especially in its differential version, where my principal contributions are the introduction of a non-inductive (i. E. "more geometric") syntax for multiplicative and exponential (differential) linear logic nets and the study of the relationship between experiments of relational semantics and Taylor expansion of a linear logic net, which leads to simplify the proof of the injectivity of relational semantics for acyclic and connected nets; 2) the call-by-value lambda calculus studied from the point of view of linear logic, where my principal contributions are the study of the call-by-value beta-reduction (and some abstract machines implementing it) and the definition of an extension of the call-by-value beta-reduction which is induced by the "boring" Girard's translation of lambda-terms into multiplicative and exponential linear logic nets
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BARROSO, GIOVANNI CORDEIRO. "A STUDY ON COLORED PETRI NETS AND A PROGRAM TO ANALYZE COLORED PETRI NETS: ANARCO." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1987. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=14192@1.
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A modelagem de sistemas que apresentam subsistemas idênticos, por intermédio de Redes de Petri, conduz à geração de grafos de grandes dimensões com diversos componentes indênticos.
As extensões às Redes de Petri que permitem diferenciar estes diversos subsistemas, por intermédio da distinção das fichas nelas contidas, receberam o nome de Redes de Petri Coloridas.
Neste trabalho, são apresentados algumas propostas existentes na literatura sobre Redes de Petri Coloridas, bem como é desenvolvido um programa de análise baseado em uma dessas propostas - a de kurt Jensen.
O programa analisa as propriedades de uma Rede de Petri Colorida, tais como limitação, vitalidade e capacidade de reinicialização, através do método de enumeração de marcações.The modeling of sistems which have identical sub-systems, by means of Petri nets, leads to the generation of large scale graphs with identical components. The extensions of Petri nets, which afford the possibility of distinguishing these sub-systems through the distinction of the tokens within the net, are called colored Petri nets. This work presents some colored Petri net proposals existent in literature and an analysis code based on one of these proposals - the Kurt Jensen one. This program analyses through the mark enumeration method, the colored Petri net properties, such as boundedness, liveness and reinicialization.
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Eirund, Helmut, and Richard Sethmann. "NetS-X : Netzsicherheit lernen mit Spaß." Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/2966/.
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Das Gebiet der Netzsicherheit ist ein schwer zu lehrendes und mühsam zu lernendes Fach in der Informatikausbildung. Dies hat verschiedene Gründe, z.B. erfordert es Fachkenntnis, die jenseits von bunten Bildern zu vermitteln ist und sich dabei mit geringer Halbwertszeit weiterentwickelt. Echte Bedrohungsszenarien müssen unter Laborbedingungen nachgestellt werden, und der Umgang mit den Sicherheitswerkzeugen ist sehr komplex. Auf der einen Seite muss das System konzeptionell verstanden werden und auf der anderen Seite sind viele Details in der Konfiguration von Firewalls, Netz-Komponenten und –Werkzeugen für klassische Prüfungssituationen in der Ausbildung anzuwenden. Mit NetS-X (Network Security Experience) stellen wir einen laufenden Prototyp einer e-learning Plattform vor, mit der ein weiter Bereich von Sicherheitsszenarien vermittelt werden kann. Dabei wird der Lernende in einem Spielsystem mit Situationen konfrontiert, die er in einer echten, auf Linux basierenden typischen IT-Infrastruktur eines Unternehmens beherrschen muss. Die sicherheitsrelevanten Aktivitäten des Lernenden, z.B. der Einsatz von Monitor-Werkzeugen oder die Konfiguration von Netz-Komponenten werden dabei nicht simuliert, sondern real durchgeführt und durch Prozesse des Spielsystems beobachtet und bewertet. Autorenwerkzeuge ermöglichen den Lehrenden und Spielern, selber neue Spielsituationen, Sicherheitsszenarien oder Wissenskomponenten in das System zu integrieren.
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Masapati, Gulammahammad Hasanasaheb. "Performance prediction using timed Petri nets." Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/5155.
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Kajitani, Yoshio. "Forecasting time series with neural nets." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39836.pdf.
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Wicker, Andrew White. "Interest-Matching Comparisons using CP-nets." NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-12142006-120734/.
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The formation of internet-based social networks has revived research on traditional social network models as well as interest-matching, or match-making, systems. In order to automate or augment the process of interest-matching, we follow the trend of qualitative decision theory by using qualitative preference information to represent a user's interests. In particular, a common form of preference statements for humans is used as the motivating factor in the formalization of ceteris paribus preference semantics. This type of preference information led to the development of conditional preference networks (CP-nets). This thesis presents a method for the comparison of CP-net preference orderings which allows one to determine a shared interest level between agents. Empirical results suggest that distance measure for preference orderings represented as CP-nets is an effective method for determining shared interest levels. Furthermore, it is shown that differences in the CP-net structure correspond to differences in the shared interest levels which are consistent with intuition. A generalized Kemeny and Snell axiomatic approach for distance measure of strict partial orderings is used as the foundation on which the interest-matching comparisons are based.
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Reinhard, Wolfgang, Michael Mascher, Senol Gül, and Johannes Magenheim. "NetS-X – Netzsicherheit lernen mit Spaß." Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2013/6433/.
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Die Evaluierung von Lehrveranstaltungen hat in vielen Lehreinrichtungen eine lange Tradition. In diesen klassischen Evaluierungsszenarien werden einmalig pro Semester Umfragebögen an die Studierenden verteilt und anschließend manuell ausgewertet. Die Ergebnisse sind dann zumeist am Ende der Vorlesungszeit vorhanden und geben einen punktuellen Einblick in die Qualität der Lehrveranstaltung bis zum Zeitpunkt der durchgeführten Evaluation. In diesem Artikel stellen wir das Konzept des Rapid Feedback, seine Einsatzmöglichkeiten in universitären Lehrveranstaltungen und eine prototypische Integration in eine koaktive Lern- und Arbeitsumgebung vor.
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SANTOS, RAFAEL DE OLIVAES V. DOS. "COMBINING MLP NEURAL NETS FOR CLASSIFICATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2001. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1890@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREsta dissertação investigou a criação de comitês de classificadores baseados em Redes Neurais Multilayer Perceptron (Redes MLP, abreviadamente). Isso foi feito em dois passos: primeiro, aplicando-se procedimentos para criação de redes complementares, i.e, redes individualmente eficazes mas que cometem erros distintos; segundo, testando- se sobre essas redes alguns dos principais métodos de combinação disponíveis. Dentre os procedimentos para criação de redes complementares, foi dado enfoque para os baseados em alteração do conjunto de treinamento. Os métodos Bootstrap e Arc-x4 foram escolhidos para serem utilizados no estudo de casos, juntamente com o método RDP (Replicação Dirigida de Padrões). No que diz respeito aos métodos de combinação disponíveis, foi dada particular atenção ao método de combinação por integrais nebulosas. Além deste método, implementou-se combinação por média, votação por pluralidade e Borda count. As aplicações escolhidas para teste envolveram duas vertentes importantes na área de visão computacional - Classificação de Coberturas de Solo por Imagens de Satélite e Reconhecimento de Expressões Faciais. Embora ambas pertençam à mesma área de conhecimento, foram escolhidas de modo a representar níveis de dificuldade diferentes como tarefas de classificação - enquanto a primeira contou com um grande número de padrões disponíveis, a segunda foi comparativamente limitada nesse sentido. Como resultado final, comprovou-se a viabilidade da utilização de comitês em problemas de classificação, mesmo com as possíveis variações de desempenho relacionadas com a complexidade desses problemas. O método de combinação baseado em integrais nebulosas mostrou-se particularmente eficiente quando associado ao procedimento RDP para formação das redes comissionadas, mas nem sempre foi satisfatório. Considerado individualmente, o RDP tem a limitação de criar, no máximo, tantas redes quanto forem as classes consideradas em um problema; porém, quando este número de redes foi considerado como base de comparação, o RDP se mostrou, na média de todos os métodos de combinação testados, mais eficaz que os procedimentos Bootstrap e Arc-x4. Por outro lado, tanto o Bootstrap quanto o Arc-x4 têm a importante vantagem de permitirem a formação de um número crescente de membros, o que quase sempre acarretou em melhorias de desempenho global em relação ao RDP.
The present dissertation investigated the creation of classifier committees based on Multilayer Perceptron Neural Networks (MLP Networks, for short). This was done in two parts: first, by applying procedures for creating complementary networks, i.e., networks that are individually accurate but cause distinct misclassifications; second, by assessing different combining methods to these network`s outputs. Among the procedures for creating committees members, the main focus was set to the ones based on changes to the training set . Bootstrap and Arc-x4 were chosen to be used at the experiments, along with the RDP procedure (translated as Driven Pattern Replication). With respect to the available combining methods, special attention was paid to fuzzy integrals combination. Average combination, plurality voting and Borda count were also implemented. The chosen experimental applications included interesting branches from computer vision: Land Cover Classification from Satellite Images and Facial Expression Recognition. These applications were specially interesting, in the sense they represent two different levels of difficulty as classification tasks - while the first had a great number of available patterns, the second was comparatively limited in this way. This work proved the viability of using committees in classification problems, despite the small performance fluctuations related to these problems complexity. The fuzzy integrals method has shown to be particularly interesting when coupled with the RDP procedure for committee creation, but was not always satisfactory. Taken alone, the RDP has the limitation of creating, at most, as many networks as there are classes to be considered at the problem at hand; however, when this number of networks was considered as the basis for comparison, this procedure outperformed, taking into account average combining results, both Bootstrap and Arc- x4. On the other hand, these later procedures have the important advantage of allowing the creation of an increasing number of committee members, what almost always increased global performance in comparison to RDP.
Esta disertación investigó la creación de comités de clasificadores basados en Redes Neurales Multilayer Perceptron (Redes MLP, abreviadamente). Esto fue ejecutado en dos pasos: primeiro, aplicando procedimentos para la creación de redes complementares, esto es, redes que individualmente son eficaces pero que cometen erros diferentes; segundo, probando sobre esas redes, algunos de los principales métodos de combinación disponibles. Dentro de los procedimentos para la creación de redes complementares, se eligieron los basados en alteración del conjunto de entrenamiento. Los métodos Bootstrap y Arc-x4 fueron seleccionados para utilizarlos em el estudio de casos, conjuntamente con el método RDP (Replicación Dirigida de Padrones). Con respecto a los métodos de combinación disponibles, se le dió particular atención al método de combinación por integrales nebulosas. Además de este método, se implementaron: combinación por media, votación por pluralidad y Borda cont. Las aplicaciones seleccionadas para pruebas consideran dos vertientes importantes en la área de visión computacional - Clasificación de Coberturas de Suelo por Imágenes de Shastalite y Reconocimiento de Expresiones Faciales. Aunque ambas pertencen a la misma área de conocimento, fueron seleccionadas de modo con diferentes níveles de dificuldad como tareas de clasificación - Mientras la primera contó con un gran número de padrones disponibles, la segunda fue comparativamente limitada em ese sentido. Como resultado final, se comprobó la viabilidad de la utilización de comités en problemas de clasificación, incluso con las posibles variaciones de desempeño relacionadas con la complejidad de esos problemas. El método de combinación basado en integrales nebulosas se mostró particularmente eficiente asociado al procedimiento RDP para formación de las redes comisionadas, pero no siempre fue satisfactorio. Considerado individualmente, el RDP tiene la limitación de crear, como máximo, tantas redes como clases consideradas en un problema; sin embargo, cuando el número de redes fue considerado como base de comparación, el RDP se mostró más eficaz, en la media de todos los métodos de combinación, que los procedimentos Bootstrap y Arc-x4. Por otro lado, tanto el Bootstrap como el Arc-x4 tiene la importante ventaja de permitir la formación de un número cresciente de miembros, lo que generalmente mejora el desempeño global en relación al RDP.
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Kyratzoglou, I. M. (Ioannis M. ). "Computer aided design for Petri Nets." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14669.
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Allen, Thomas E. "CP-nets: From Theory to Practice." UKnowledge, 2016. http://uknowledge.uky.edu/cs_etds/42.
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Conditional preference networks (CP-nets) exploit the power of ceteris paribus rules to represent preferences over combinatorial decision domains compactly. CP-nets have much appeal. However, their study has not yet advanced sufficiently for their widespread use in real-world applications. Known algorithms for deciding dominance---whether one outcome is better than another with respect to a CP-net---require exponential time. Data for CP-nets are difficult to obtain: human subjects data over combinatorial domains are not readily available, and earlier work on random generation is also problematic. Also, much of the research on CP-nets makes strong, often unrealistic assumptions, such as that decision variables must be binary or that only strict preferences are permitted. In this thesis, I address such limitations to make CP-nets more useful. I show how: to generate CP-nets uniformly randomly; to limit search depth in dominance testing given expectations about sets of CP-nets; and to use local search for learning restricted classes of CP-nets from choice data.
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Mazza, Damiano. "Interaction nets : semantics and concurrent extensions." Aix-Marseille 2, 2006. http://theses.univ-amu.fr.lama.univ-amu.fr/2006AIX22069.pdf.
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Ghahremani, Azghandi Nargess. "Petri nets, probability and event structures." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9936.
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Models of true concurrency have gained a lot of interest over the last decades as models of concurrent or distributed systems which avoid the well-known problem of state space explosion of the interleaving models. In this thesis, we study such models from two perspectives. Firstly, we study the relation between Petri nets and stable event structures. Petri nets can be considered as one of the most general and perhaps wide-spread models of true concurrency. Event structures on the other hand, are simpler models of true concurrency with explicit causality and conflict relations. Stable event structures expand the class of event structures by allowing events to be enabled in more than one way. While the relation between Petri nets and event structures is well understood, the relation between Petri nets and stable event structures has not been studied explicitly. We define a new and more compact unfoldings of safe Petri nets which is directly translatable to stable event structures. In addition, the notion of complete finite prefix is defined for compact unfoldings, making the existing model checking algorithms applicable to them. We present algorithms for constructing the compact unfoldings and their complete finite prefix. Secondly, we study probabilistic models of true concurrency. We extend the definition of probabilistic event structures as defined by Abbes and Benveniste to a newly defined class of stable event structures, namely, jump-free stable event structures arising from Petri nets (characterised and referred to as net-driven). This requires defining the fundamental concept of branching cells in probabilistic event structures, for jump-free net-driven stable event structures, and by proving the existence of an isomorphism among the branching cells of these systems, we show that the latter benefit from the related results of the former models. We then move on to defining a probabilistic logic over probabilistic event structures (PESL). To our best knowledge, this is the first probabilistic logic of true concurrency. We show examples of expressivity achieved by PESL, which in particular include properties related to synchronisation in the system. This is followed by the model checking algorithm for PESL for finite event structures. Finally, we present a logic over stable event structures (SEL) along with an account of its expressivity and its model checking algorithm for finite stable event structures.
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Li, Yao Carleton University Dissertation Engineering Electrical. "Solution techniques for stochastic petri nets." Ottawa, 1992.
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MASCHERONI, MARCO. "Hypernets: a class of hierarchical petri nets." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/19228.
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The interest of this thesis is on modeling systems of mobile agents, systems composed of several open and autonomous components which can interact and move inside one or more environments.
Several proposal for modeling mobility have been introduced. They can be roughly divided in two categories: Petri net based formalisms, and process algebra based formalisms.
In this thesis, Petri net formalisms will mostly be considered, with particular care to formalisms which use the nets-within-nets paradigm. In models compliant to this paradigm the tokens of a Petri net can be nets themselves. Since systems of mobile agents exhibit a nesting structure, it seems natural to use this paradigm.
In particular, the focus of this dissertation is on the hypernet model, whose main characteristic is that it has a limited state space, characteristic that make it suitable to be analyzed using well known Petri net techniques.
The thesis topics range from theoretical aspects of the model to more practical issues.
From a theoretical point of view an extension of the model is introduced. It is proved that this extension preserves all the good properties of the basic model. It is also studied how to apply the well known unfolding technique to this model.
From a practical point of view is is shown how the nets-within nets paradigm can be used to model systems based on the Grid infrastructure. Moreover, a tool which allow to draw and to analyze an hypernet is discussed.
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Cesco, Arnaldo. "Decidability Of Strong Equivalences For Finite Petri Nets." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23293/.
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Tra i vari modelli di sistemi concorrenti e distribuiti proposti, le reti di Petri finite sono uno dei più studiati ed adatti
alla descrizione di questo tipo di sistemi, poiché ne ricalcano le qualità distintive. Infatti, lo stato globale di una rete di Petri è formato da una collezione (detta marking) di stati locali
(detti token). L'esecuzione di una transizione è una trasformazione locale che riguarda solo una parte dei token in un marking. Pertanto, si può interpretare un token come un processo sequenziale ed un marking come un sistema distribuito che porta avanti una computazione più complessa all'interno della quale i processi possono cooperare o competere. Le equivalenze interessanti su reti di Petri quindi devono considerare vari aspetti del modello, quali concorrenza (e relazioni di causalità), scelte e ramificazioni, invarianti.
Nella prima parte del lavoro, si studiano equivalenze su reti Place/Transition (finite) safe e bounded. Sono riportati o provati alcuni risultati riguardanti due relazioni simili tra loro, che posseggono buona parte delle proprietà elencate sopra e considerano ogni esecuzione come un oggetto matematico a sè stante, detto processo. Le prove sono basate su una generalizzazione, per mezzo di indici, della tecnica di prova a marking ordinati usata da Vogler per dimostrare la decidibilità di fully-concurrent bisimilarity su reti safe.
Nella seconda parte del lavoro, si studiano equivalenze su reti Place/Transition (finite) ma con archi inibitori e senza limiti al numero di token che possono occupare un posto, dette reti PTI. In questo modello, i token possono non solo permettere l'esecuzione di una transizione, ma anche bloccarla. Si formula una equivalenza, pti-place bisimilarity, che estende conservativamente place-bisimilarity e se ne prova la decidibilità. Questa è la prima volta che una equivalenza è provata essere decidibile per reti PTI. Tuttavia, rispetto alle altre equivalenze note, non è coinduttiva.
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Hiroki, Carlos Hiroji. "Papel das Neutrophil Extracellular Traps no controle da infecção por Chikungunya." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/17/17147/tde-01022019-105719/.
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O Chikungunya é um vírus reemergente que causa uma doença caracterizada por uma artralgia incapacitante que afeta milhares de pessoas. A resposta inata contra este vírus é bem descrita pela participação de macrófagos, células dendríticas e células NK, porém há poucos trabalhos que demonstram o papel dos neutrófilos nesta infecção. As Neutrophil Extracellular Traps (NETs) constituem uma rede de DNA complexada a enzimas antimicrobianas que foram descritas por combaterem diversos patógenos. Porém, não há trabalhos que demonstram sua importância em infecção por Chikungunya. Nosso objetivo foi investigar se há produção de NETs na infecção por Chikungunya, descrever seus mecanismos e demonstrar sua importância in vitro e in vivo. Observamos que neutrófilos murinos e humanos incubados com Chikungunya são capazes de produzir NETs via Toll-Like 7 e produção de espécies reativas de oxigênio. Estas NETs foram capazes de capturar o vírus e impedir sua infecção in vitro. Mais além, animais infectados com Chikungunya e tratados com rhDNAse apresentam maior carga viral e são mais suscetíveis à infecção, demonstrando sua importância in vivo. Por fim, pacientes diagnosticados em fase aguda de infecção por Chikungunya possuem elevados níveis de NETs correlacionados com uma alta carga viral.Chikungunya is a reemerging virus which causes a disease characterized by an incapacitanting arthralgia and affects thousands of people. Innate response against this virus is well described by participation of macrophages, dendritic cells and NK cells, however few works demonstrate the roe of neutrophils in this infection. Neutrophils Extracellular Traps are a web of DNA complexed with antimicrobial enzymes which were described for fighting against many pathogens. However, there are no works which demonstrate its relevance in Chikungunya infection. Our objective was to evaluate if there is release of NETs in Chikungunya infection, describe its mechanisms and demonstrate its relevance in vitro and in vivo. We observed that mouse and human neutrophils incubated with Chikungunya are able to produce NETs via Toll-Like 7 and reactive oxygen species production. These NETs were able to capture the virus and inhibit its infection in vitro. Moreover, animals infected with Chikungunya virus and treated with rhDNAse demonstrated higher viral load and are more susceptible to the infection, showing its importance in vivo. Lastly, patients diagnosed during acute infection of Chikungunya infection have high levels of NETs correlated with a high viral load.
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Tanabe, Makoto. "Timed Petri Nets and Temporal Linear Logic." 京都大学 (Kyoto University), 1999. http://hdl.handle.net/2433/181934.
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Hassan, Abubakar. "Interaction Nets : Language and Design and Implementation." Thesis, University of Sussex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506943.
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Dorman, Andrei. "Concurrency in Interaction Nets and Graph Rewriting." Phd thesis, Université Paris-Nord - Paris XIII, 2013. http://tel.archives-ouvertes.fr/tel-00937224.
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Ce travail est une étude approfondie de la concurrence dans les extensions non-déterministes des réseaux d'interaction de Lafont (langage graphique qui représente, lui, le calcul fonctionnel). Ces extensions sont de trois sortes : les réseaux multirègles, multiports et multifils, et leurs combinaisons donnent ainsi sept types de réseaux. Un premier travail consiste à déterminer une bonne sémantique pour pouvoir comparer ces extensions. On cherche à définir un sémantique opérationnelle structurelle sur les réseaux en se basant sur des technique connues de réécriture des graphes, plus particulièrement celle de " double-pushout with borrowed contexts ". Nous définissons à partir de cette méthode un système d'étiquetage des transitions donné par des règles de dérivations dans le style des langages de processus qui sont le paradigme principal pour étudier les systèmes de calcul concurrents. Nous définissons de plus une sémantique observationnelle sur les réseaux basée sur une notion paramétrique de barbe, qui permet enfin de donner avec précision une notion de traduction entre systèmes. On considère qu'une extension est plus expressive qu'une autre si tout langage de la seconde peut être traduit dans un langage de la première. Ceci nous permet de classer l'ensemble des extensions de manière hiérarchique en trois groupe selon la possibilité de traduire un système de réseau dans un autre. Du plus fort au plus faible : les réseaux contenant des multiports ; ensuite ceux contenant des multifils; enfin les réseaux multirègles. Ceci nous permet de donner un langage universel pour les réseaux dont l'étude donne un point de vue neuf sur les briques fondamentales de la concurrence.
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Shaw, Oliver James. "Modelling bacterial regulatory networks with Petri nets." Thesis, University of Newcastle Upon Tyne, 2007. http://hdl.handle.net/10443/1963.
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To exploit the vast data obtained from high throughput molecular biology, a variety of modelling and analysis techniques must be fully utilised. In this thesis, Petri nets are investigated within the context of computational systems biology, with the specific focus of facilitating the creation and analysis of models of biological pathways. The analysis of qualitative models of genetic networks using safe Petri net techniques was investigated with particular reference to model checking. To exploit existing model repositories a mapping was presented for the automatic translation of models encoded in the Systems Biology Markup Language (SBML) into the Petri Net framework. The mapping is demonstrated via the conversion and invariant analysis of two published models of the glycolysis pathway. Dynamic stochastic simulations of biological systems suffer from two problems: computational cost; and lack of kinetic parameters. A new stochastic Petri net simulation tool, NASTY was developed which addresses the prohibitive real-time computational costs of simulations by using distributed job scheduling. In order to manage and maximise the usefulness of simulation results a new data standard, TSML was presented. The computational power of NASTY provided the basis for the development of a genetic algorithm for the automatic parameterisation of stochastic models. This parameter estimation technique was evaluated on a published model of the general stress response of E. coli. An attempt to enhance the parameter estimation process using sensitivity analysis was then investigated. To explore the scope and limits of applying the Petri net techniques presented, a realistic case study investigated how the Pho and aB regulons interact to mitigate phosphate stress in Bacillus subtilis. This study made use of a combination of qualitative and quantitative Petri net techniques and was able to confirm an existing experimental hypothesis.
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Hall, Jon G. "An algebra of high level Petri nets." Thesis, University of Newcastle Upon Tyne, 1996. http://hdl.handle.net/10443/2166.
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Petri nets were introduced by C.A. Petri as a theoretical model of concurrency in which the causal relationship between actions, rather than just their temporal ordering, can be represented. As a theoretical model of concurrency, Petri nets have been widely successful. Moreover, Petri nets are popular with practitioners, providing practical tools for the designer and developer of real concurrent and distributed systems. However, it is from this second context that perhaps the most widely voiced criticism of Petri nets comes. It is that Petri nets lack any algebraic structure or modularity, and this results in large, unstructured models of real systems, which are consequently often intractable. Although this is not a criticism of Petri nets per se, but rather of the uses to which Petri nets are put, the criticism is well taken. We attempt to answer this criticism in this work. To do this we return to the view of Petri nets as a model of concurrency and consider how other models of concurrency counter this objection. The foremost examples are then the synchronisation trees of Milner, and the traces of Hoare, (against which such criticism is rarely, if ever, levelled). The difference between the models is clear, and is to be found in the richness of the algebraic characterisations which have been made for synchronisation trees in Milner's Calculus of Communicating Systems (CCS), and for traces in Hoare's Communicating Sequential Processes (CSP). With this in mind we define, in this thesis, a class of high level Petri nets, High Level Petri Boxes, and provide for them a very general algebraic description language, the High Level Petri Box Algebra, with novel ideas for synchronisation, and including both refinement and recursion among its operators. We also begin on the (probably open-ended task of the) algebraic characterisation of High Level Petri Boxes. The major contribution of this thesis is a full behavioural characterisation of the High Level Petri Boxes which form the semantic domain of the algebra. Other contributions are: a very general method of describing communication protocols which extend the synchronisation algebras of Winskel; a recursive operator that preserves finiteness of state (the best possible, given the generality of the algebra); a refinement operator that is syntactic in nature, and for which the recursive construct is a behavioural fix-point; and a notion of behavioural equivalence which is a congruence with respect to a major part of the High Level Petri Box Algebra.
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English, Sarah L. "Coloured Petri Nets for object-oriented modelling." Thesis, University of Brighton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334740.
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van't, Spijker Heleen Merel. "Modifications of perineuronal nets to regulate plasticity." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/285731.
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Modifications of perineuronal nets to regulate plasticity Heleen Merel van 't Spijker Perineuronal nets (PNNs) are macromolecular structures formed by neurons after closure of critical periods of plasticity. During development, the central nervous system (CNS) goes through critical periods of plasticity; a period when substantial changes occur to adapt to the environment, during which many synapses are formed and also discarded. When a region of the CNS has finished its development and reached an efficient neuronal circuit, the capacity for plasticity needs to be reduced to preserve the formed circuit. PNNs are formed around neurons during this period of reduced plasticity. PNNs consist of a backbone of hyaluronan, bound by chondroitin sulfate proteoglycans (CSPGs). Here, I present my studies on the possible modifications of PNNs to regulate plasticity. Firstly, I have investigated the potential use of 4-methylumbelliferone (4-MU) to reduce PNN formation in vivo. 4-MU reduces the formation of hyaluronan. Since hyaluronan is the backbone of PNNs, I hypothesized 4-MU treatment would reduce PNN formation. For this study, I developed a method to orally administer 4-MU to rats. Subsequently, I investigated whether 4-MU treatment can improve recovery of rats after spinal cord injury, both with behavioural tests and with immunohistochemistry. Secondly, I have investigated a new binding partner of PNNs, neuronal pentraxin 2 (Nptx2). Nptx2 is secreted by neurons and regulates AMPA receptor diffusion. Nptx2 knockout mice show a prolonged critical period of plasticity in the visual cortex. Here, I have identified Nptx2 as a new binding partner of PNNs. Nptx2 is found in isolated PNN protein preparations and is removed from the surface of neurons by digestion of PNNs with chondroitinase ABC. I also determined Nptx2 facilitates PNN formation in vitro. Addition of Nptx2 to the medium of cortical neurons leads to an increase of neurons that start to form PNNs, as well as an increase in size and density of PNNs. These findings indicate Nptx2 may be used as a modulator of PNNs. Thirdly, I investigated the interaction between Nptx2 and PNNs. I developed a sandwich ELISA to determine which glycan chains from PNNs bind to Nptx2. Nptx2 binds to chondroitin sulfate E and hyaluronan. To investigate the binding properties of Nptx2, I performed quartz crystal microbalance with dissipation monitoring for Nptx2 films. Furthermore, I developed crystals of purified Nptx2 and hyaluronan for x-ray crystallography. The here presented results provide new insights in potential approaches to modulate PNN formation. Both lines of research provide a further understanding of the factors which regulate PNNs and may allow for the development of treatments for PNN related disorders.
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VIEIRA, BRUNO LOPES. "EXTENDING PROPOSITIONAL DYNAMIC LOGIC FOR PETRI NETS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24052@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
Lógica Proposicional Dinâmica (PDL) é um sistema lógico multi-modal utilizada para especificar e verificar propriedades em programas sequenciais. Redes de Petri são um formalismo largamente utilizado na especificação de sistemas concorrentes e possuem uma interpretação gráfica bastante intuitiva. Neste trabalho apresentam-se extensões da Lógica Proposicional Dinâmica onde os programas são substituídos por Redes de Petri. Define-se uma codificação composicional para as Redes de Petri através de redes básicas, apresentando uma semântica composicional. Uma axiomatização é definida para a qual o sistema é provado ser correto, e completo em relação à semântica proposta. Três Lógicas Dinâmicas são apresentadas: uma para efetuar inferências sobre Redes de Petri Marcadas ordinárias e duas para inferências sobre Redes de Petri Estocásticas marcadas, possibilitando a modelagem de cenários mais complexos. Alguns sistemas dedutivos para essas lógicas são apresentados. A principal vantagem desta abordagem concerne em possibilitar efetuar inferências sobre Redes de Petri [Estocásticas] marcadas sem a necessidade de traduzí-las a outros formalismos.
Propositional Dynamic Logic (PDL) is a multi-modal logic used for specifying and reasoning on sequential programs. Petri Net is a widely used formalism to specify and to analyze concurrent programs with a very intuitive graphical representation. In this work, we propose some extensions of Propositional Dynamic Logic for reasoning about Petri Nets. We define a compositional encoding of Petri Nets from basic nets as terms. Second, we use these terms as PDL programs and provide a compositional semantics to PDL Formulas. Then we present an axiomatization and prove completeness regarding our semantics. Three versions of Dynamic Logics to reasoning with Petri Nets are presented: one of them for ordinary Marked Petri Nets and two for Marked Stochastic Petri Nets yielding to the possibility of model more complex scenarios. Some deductive systems are presented. The main advantage of our approach is that we can reason about [Stochastic] Petri Nets using our Dynamic Logic and we do not need to translate it into other formalisms. Moreover our approach is compositional allowing for construction of complex nets using basic ones.
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Wiley, Richard Paul. "Performance analysis of Stochastic Timed Petri Nets." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15002.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaves 305-310.
by Richard Paul Wiley.
Sc.D.
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Lucic, Diana. "On exact equilibrium distributions of stochastic Petri nets /." Title page, contents and summary only, 1990. http://web4.library.adelaide.edu.au/theses/09PH/09phl937.pdf.
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Neumann, Ariane [Verfasser]. "Neutrophil extracellular traps (NETs): Mechanisms of NET induction, bacterial NET degradation and host protection against bacterial degradation / Ariane Neumann." Hannover : Bibliothek der Tierärztlichen Hochschule Hannover, 2014. http://d-nb.info/1065267975/34.
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Reyes, Fernanda D. "Social Safety Nets: An Analysis of American Social Safety Net Policy and The Ethics Behind Welfare Rights." Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/cmc_theses/1365.
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The purpose of this thesis is to analyze current housing and supplemental income programs on a national level to measure success and failures of different programs like Temporary Assistance to Needy Families, Earned Income Tax Credit, and Housing Vouchers. Furthermore, this thesis attempt to discuss questions of ethics and precedent in determining to what degree the United States should engage in social safety net policies. This paper analyzes contemporary American social safety net policies on the basis of their cost to American taxpayers as well as how well it benefits those in poverty.
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Holtrop, G. "Statistical modelling of the selectivity of trawl nets." Thesis, University of Aberdeen, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263211.
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This thesis develops statistical methodology for modelling the selectivity of fishing nets, using data from covered codend experiments of fishing trawls. First, the effects of subsampling an experimental catch instead of measuring the entire catch are investigated. Often the subsample is not taken at random. This leads to bias in the selectivity parameter estimates. Simulations show that the effects of non-random subsampling are minimised when equal proportions are sampled from the test and the control net. A model is developed for describing the selectivity of a net with a window panel inserted. This model quantifies the selectivity of both the codend and the window panel, which can then be combined. The model is used to investigate the selectivity of different window panels and their contribution to the combined selectivity. Traditionally, selectivity has been modelled as a fixed and random effects model, estimated in two stages. As an alternative, Markov chain Monte Carlo techniques are explored. A Bayesian selectivity model is formulated, and the effect of the prior distribution on the variance components is investigated. The posterior distribution is relatively insensitive to a prior distribution having variation of similar magnitude as the variation present in the data. For model selection, the p-value approach applied to the posterior marginal densities is more useful than the Bayes and pseudo-Bayes factors. The Bayesian selectivity model is extended to include variation between seasons and variation between trips. The new model is applied to a data set containing seasonal variation. Finally, a Bayeisan multi-species model is developed that accounts for dependencies between species. This gives more precise selectivity parameter estimates. It also reduces bias in the parameter estimates by accounting for mechanisms behind non-random missing data.
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Erkursun, Nazife. "Convergence Of Lotz-raebiger Nets On Banach Spaces." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12612108/index.pdf.
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The concept of LR-nets was introduced and investigated firstly by H.P. Lotz in [27] and by F. Raebiger in [30]. Therefore we call such nets Lotz-Raebiger nets, shortly LR-nets. In this thesis
we treat two problems on asymptotic behavior of these operator nets.
First problem is to generalize well known theorems for Ces`aro averages of a single operator to LR-nets, namely to generalize the Eberlein and Sine theorems. The second problem is related
to the strong convergence of Markov LR-nets on L1-spaces. We prove that the existence of a lower-bound functions is necessary and sufficient for asymptotic stability of LR-nets of
Markov operators.
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Coleman, James L. "Stochastic Petri Nets with product form equilibrium distributions /." Title page, contents and summary only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phc6922.pdf.
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Radlinski, Lukasz. "Improved Software Project Risk Assessment Using Bayesian Nets." Thesis, Queen Mary, University of London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509672.
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Shum, Ho-ma Ada, and 岑賀美. "Perceptions of school culture: NETS vis-à-visstudents." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31962543.
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Hancock, Peter J. B. "Coding strategies for genetic algorithms and neural nets." Thesis, University of Stirling, 1993. http://hdl.handle.net/1893/39.
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The interaction between coding and learning rules in neural nets (NNs), and between coding and genetic operators in genetic algorithms (GAs) is discussed. The underlying principle advocated is that similar things in "the world" should have similar codes. Similarity metrics are suggested for the coding of images and numerical quantities in neural nets, and for the coding of neural network structures in genetic algorithms. A principal component analysis of natural images yields receptive fields resembling horizontal and vertical edge and bar detectors. The orientation sensitivity of the "bar detector" components is found to match a psychophysical model, suggesting that the brain may make some use of principal components in its visual processing. Experiments are reported on the effects of different input and output codings on the accuracy of neural nets handling numeric data. It is found that simple analogue and interpolation codes are most successful. Experiments on the coding of image data demonstrate the sensitivity of final performance to the internal structure of the net. The interaction between the coding of the target problem and reproduction operators of mutation and recombination in GAs are discussed and illustrated. The possibilities for using GAs to adapt aspects of NNs are considered. The permutation problem, which affects attempts to use GAs both to train net weights and adapt net structures, is illustrated and methods to reduce it suggested. Empirical tests using a simulated net design problem to reduce evaluation times indicate that the permutation problem may not be as severe as has been thought, but suggest the utility of a sorting recombination operator, that matches hidden units according to the number of connections they have in common. A number of experiments using GAs to design network structures are reported, both to specify a net to be trained from random weights, and to prune a pre-trained net. Three different coding methods are tried, and various sorting recombination operators evaluated. The results indicate that appropriate sorting can be beneficial, but the effects are problem-dependent. It is shown that the GA tends to overfit the net to the particular set of test criteria, to the possible detriment of wider generalisation ability. A method of testing the ability of a GA to make progress in the presence of noise, by adding a penalty flag, is described.
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Magbity, Edward Brima. "Methods for entomological evaluation of treated bed nets." Thesis, London School of Hygiene and Tropical Medicine (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324915.
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Djemame, Karim. "Distributed simulation of high-level algebraic Petri nets." Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301624.
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Usher, Michelle M. "A concurrent visual language based on Petri nets." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366506.
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Cui, Qing Ming. "Parallel and distributed simulation of timed Petri nets." Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245946.
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Ng, Hoi Sum. "Petri nets for fault diagnosis and distribution automation." Thesis, University of Strathclyde, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366530.
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Bilinski, Krzysztof. "Application of Petri nets in parallel controller design." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336830.
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Rhodes, Bradley James. "PHISH-nets : planning heuristically in situated hybrid networks." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/62335.
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Frean, Marcus Roland. "Small nets and short paths : optimising neural computation." Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/13850.
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The thesis explores two aspects of optimisation in neural network research. 1. The question of how to find the optimal feed-forward neural network architecture for learning a given binary classification is addressed. The so-called constructive approach is reviewed whereby intermediate, hidden, units are built as required for the particular problem. Current constructive algorithms are compared, and three new methods are introduced. One of these, the Upstart algorithm, is shown to out-perform all other constructive algorithms of this type. This work led on to the ancillary problem of finding a satisfactory procedure for changing the weight values of an individual unit in a network. The new thermal perceptron rule is described and is shown to compare favorably with its competitors. Finally the spectrum of possible learning rules is surveyed. 2. Neurobiologically inspired algorithms for mapping between spaces of different dimensions are applied to a classic optimisation problem, the Travelling Salesman Problem. Two new methods are described that can tackle the general symmetric form of the TSP, thus overcoming the restriction on other neural network algorithms to the geometric case.