This term project focuses on algorithms for pattern matching used in modern IDS. The main focus is on regular expression matching. It deals with methods based on deterministic and nondeterministic finite automata, hybrid methods and with method based on regular expressions as programing langue for specialised processors. Implementation of pattern matching units based on some of described methodologies is described in next part. Methodology for resource consumption estimation is also described. Developed software system for unit generation is described in the next part. In the final part results are presented and discused.

This work deals with two basic operations over finite automata. Determination of nondeterministic finite automata and minimization of deterministic finite automata. For these two operations I proposed sequential algorithms that are parallelizable. I deal mainly with finding the speedup of SSE instructions, or use the OpenMP library. The trend today is mainly in increasing the number of processors, so I propose parallel algorithms for multiple processors. When searching for the optimal solution, I will be to examine other ways to achieve speedup, for example efficient saving of the data structures in memory.

Yes / Regular language inference, initiated by Angluin, has many developments, including applications in software engineering and testing. However, the capability of finite automata to model the system data is quite limited and, in many cases, extended finite state machine formalisms, that combine the system control with data structures, are used instead. The application of Angluin-style inference algorithms to extended state machines would involve constructing a minimal deterministic extended finite state machine consistent with a deterministic 3-valued deterministic finite automaton. In addition to the usual, accepting and rejecting, states of finite automaton, a 3-valued deterministic finite automaton may have “don't care” states; the sequences of inputs that reach such states may be considered as accepted or rejected, as is convenient. The aforementioned construction reduces to finding a minimal deterministic finite automaton consistent with a 3-valued deterministic finite automaton, that preserves the deterministic nature of the extended model that also handles the data structure associated with it. This paper investigates fundamental properties of extended finite state machines in relation to Angluin's language inference problem and provides an inference algorithm for such models.

Master of Science / Department of Computing and Information Sciences / Torben Amtoft / An EFSM (Extended Finite State Machine) is a tuple (S, T, E, V) where S is a finite set of states, T is a finite set of transitions, E is a finite set of events, and V is a finite set of variables. Every transition t in T has a source state and a target state, both in S. There is a need to develop a GUI which aids in building such machines and simulating them so that a slicing algorithm can be implemented on such graphs. This was the main idea of Dr. Torben Amtoft, who has actually written the slicing algorithm and wanted this to be implemented in code. The project aims at implementing a GUI which is effective to simulate and build the graph with minimum user effort. Poor design often fails to attract users. So, the initial effort is to build a simple and effective GUI which serves the purpose of taking input from the user, building graphs and simulating it. The scope of this project is to build and implement an interface so that the users can do the following in an effective way:  Input a specification of an EFSM  Store and later retrieve EFSMs  Displaying an EFSM in a graphical form  Simulating the EFSM  Modify an EFSM  Implement the slicing algorithm All the above mentioned features must be integrated into the GUI and it should only fail if the input specification is wrong.

Em Teoria dos Jogos, o Dilema do Prisioneiro para N Participantes (DPNP) é o problema que representa, em sua forma elementar, o paradoxo que gera as dificuldades existentes na formação da cooperação entre mais de dois agentes. Diversos trabalhos foram e continuam sendo feitos sobre esse tema, no sentido de compreender melhor os fatores que influenciam o surgimento e a evolução da cooperação numa sociedade. Neste trabalho, o objetivo principal é o de analisar o impacto do poder expressivo de um modelo de representação de estratégias neste surgimento e evolução. Para tal, foi desenvolvido um modelo computacional de jogos evolutivos, onde agentes participam repetidamente do DPNP. Nele, as estratégias que definem qual será a jogada de um determinado agente são desenvolvidas e selecionadas através de mecanismos de mutação e reprodução daquelas que obtiveram melhores resultados nas iterações anteriores, e implementadas através de duas representações com diferentes poderes computacionais: autômatos finitos e autômatos adaptativos. Este modelo foi implementado num sistema denominado S2E2 onde foram executados diversos experimentos de simulação. Através da comparação dos resultados obtidos para ambas as representações, verificou-se que em ambos os casos a sociedade consegue atingir, após um período inicial, um nível de cooperação relativamente alto e estável. A análise das estratégias utilizadas pelos agentes, entretanto, mostrou que o uso de autômatos adaptativos resulta em uma pequena vantagem, embora estatisticamente não significativa, pois permite surgir estratégias que visam retornar a uma situação de cooperação. / In Game Theory, the n-Players Prisoner\'s Dilemma (NPPD) is a problem that represents, in its elementary form, the paradox that leads to the existing difficulties in the development of cooperation between two or more agents. Many works were and are still being done about this subject, trying to better understand the factors that influence the development and evolution of cooperation in a society. In this work, the main objective is to analyze the impact of the expressive power of the strategies representation model in this development and evolution. In order to do so, a computational model of evolutionary games was developed, where agents are spatially distributed and participate on the NPPD with five participants, interacting only with their neighbors. In this model, the strategies that define the agent\'s decisions are developed and selected through mutation and reproduction of those strategies that obtained better results in the last iterations, and they are implemented by two representations with different computational power: finite automata and adaptative automata. This model was implemented in a system called S2E2 and several simulation experiments were carried on. Comparing the results obtained in those experiments, it was verified that after an initial period of time in both cases the society achieved a relatively high and stable level of cooperation. On the other hand, the analysis of the strategies used by the agents showed that the use of adaptative automata resulted in a slight advantage, although not statistically significative, because they allow the emergence of strategies that return to a situation of cooperation.

Em Teoria dos Jogos, o Dilema do Prisioneiro para N Participantes (DPNP) é o problema que representa, em sua forma elementar, o paradoxo que gera as dificuldades existentes na formação da cooperação entre mais de dois agentes. Diversos trabalhos foram e continuam sendo feitos sobre esse tema, no sentido de compreender melhor os fatores que influenciam o surgimento e a evolução da cooperação numa sociedade. Neste trabalho, o objetivo principal é o de analisar o impacto do poder expressivo de um modelo de representação de estratégias neste surgimento e evolução. Para tal, foi desenvolvido um modelo computacional de jogos evolutivos, onde agentes participam repetidamente do DPNP. Nele, as estratégias que definem qual será a jogada de um determinado agente são desenvolvidas e selecionadas através de mecanismos de mutação e reprodução daquelas que obtiveram melhores resultados nas iterações anteriores, e implementadas através de duas representações com diferentes poderes computacionais: autômatos finitos e autômatos adaptativos. Este modelo foi implementado num sistema denominado S2E2 onde foram executados diversos experimentos de simulação. Através da comparação dos resultados obtidos para ambas as representações, verificou-se que em ambos os casos a sociedade consegue atingir, após um período inicial, um nível de cooperação relativamente alto e estável. A análise das estratégias utilizadas pelos agentes, entretanto, mostrou que o uso de autômatos adaptativos resulta em uma pequena vantagem, embora estatisticamente não significativa, pois permite surgir estratégias que visam retornar a uma situação de cooperação. / In Game Theory, the n-Players Prisoner\'s Dilemma (NPPD) is a problem that represents, in its elementary form, the paradox that leads to the existing difficulties in the development of cooperation between two or more agents. Many works were and are still being done about this subject, trying to better understand the factors that influence the development and evolution of cooperation in a society. In this work, the main objective is to analyze the impact of the expressive power of the strategies representation model in this development and evolution. In order to do so, a computational model of evolutionary games was developed, where agents are spatially distributed and participate on the NPPD with five participants, interacting only with their neighbors. In this model, the strategies that define the agent\'s decisions are developed and selected through mutation and reproduction of those strategies that obtained better results in the last iterations, and they are implemented by two representations with different computational power: finite automata and adaptative automata. This model was implemented in a system called S2E2 and several simulation experiments were carried on. Comparing the results obtained in those experiments, it was verified that after an initial period of time in both cases the society achieved a relatively high and stable level of cooperation. On the other hand, the analysis of the strategies used by the agents showed that the use of adaptative automata resulted in a slight advantage, although not statistically significative, because they allow the emergence of strategies that return to a situation of cooperation.

Original results in computational and combinatorial theory of reset words in transition systems, road coloring in directed graphs, and discontinuous input processing in formal languages are presented, including strong lower bounds on subset synchronization thresholds, lower bounds on descriptive power of jumping finite automata, and corresponding complexity classifications.

This thesis formalizes a model of bounded rationality in extensive-form games called game-playing schemata. In this model, the strategies are repre- sented by a structure consisting of a deterministic finite automaton and two computational functions. The automaton represents a structured memory of the player, while the functions represent the ability of the player to identify efficient abstractions of the game. Together, the schema is a realization of a pure strategy which can be implemented by a player in order to play a given game. The thesis shows how to construct correctly playing schema for every pure strategy in any multi-player extensive-form game with perfect recall and how to evaluate its complexity. It proves that equilibria in schemata strategies always exist and computing them is PPAD-hard. Moreover, for a class of efficiently representable strategies, computing MAXPAY-EFCE can be done in polynomial time. 1

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Cette thèse a pour but d’étudier des propriétés structurelles d’automates étendant celle du déterminisme, et les langages pouvant être dénotés par une expression rationnelle dont l’automate des positions présente l’une de ces propriétés. Si Book et al. ont montré que tous les langages rationnels peuvent être reconnus par un automate des positions non-ambigu, Brüggemann-Klein et Wood ont montré que ceux pouvant l’être par un automate des positions déterministe forment une famille strictement incluse dans celle des rationnels. Nous nous intéressons aux extensions de cette famille, en cherchant à caractériser leurs langages, et à étudier leur hiérarchie interne et leur inclusion entre elles. / This thesis aims to study structural properties of automata extending determinism, and the languages that can be denoted by a regular expression of which the position automaton has one such property. If Book et al. showed that all regular languages can be recognized by an unambiguous position automaton, Brüggemann-Klein and Wood showed that only a proper subset of them can be recognized by a deterministic position automaton. We focus on extensions of this subfamily, by seeking to characterize their languages, and to study their internal hierarchy and how they relate to each other.