A ubiquitous problem for all foragers is the trade-off between acquiring food energy while simultaneously avoiding the risk of predation. In central montane Alberta I modelled how ungulate forage changes with succession within cutblocks and the implications for forage availability to ungulates under current harvest regimes. Because cutblocks are discrete patches in space, I developed a dynamic state variable model for an ungulate to explore under what conditions an individual forager could (1) behaviourally avoid predation within a patch through inactivity, (2) overcome patch isolation when confronted with predation during transit between patches, and (3) alter patch use across a home range to optimize fitness. The model includes the requirement to process forage into energy through rumination behaviour that constrains foraging, and compares outcomes under a time-minimizing (sigmoid) and energy maximizing (linear) fitness functions. When an ungulate is in high energetic state, inactivity provides an effective behavioural refuge, or animals prioritize safety over energy gain, individuals avoid predation within patches reducing the need to move between patches. When energy acquisition is prioritized, individuals are at a low energetic state, or within patch anti-predator behaviours are ineffective, individuals move among patches to avoid predators in space, and configuration of the patches influences fitness. When model results were qualitatively compared to activity patterns and cutblock use of female, GPS-collared elk appear to follow a time minimizing strategy in their patch use across the home range and with their activity within riskier patches. I discuss the implications of these findings for the management of elk and cutblocks in west central Alberta.

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Regression testing is performed after existing source code has been modified to verify that no new faults have been introduced by the changes. Test case selection can be used to reduce the effort of regression testing by selecting a smaller subset of the test suite for later execution. Several criteria and objectives can be used as constraints that should be satisfied by the selection process. One common criteria is function coverage, which can be represented by a coverage matrix that maps test cases to methods under test. The process of generating and evaluating these matrices can be very time consuming for large matrices since their complexity increases exponentially with the number of tests included. To the best of our knowledge, no techniques for reducing execution matrix size have been proposed. This thesis develops a matrix-reduction technique based on analysis of call stack data. It studies the effects of limiting the call stack depth in terms of coverage accuracy, matrix size, and generation costs. Further, it uses a tool that can instrument Java projects using Java’s instrumentation API to collect coverage information on open-source Java projects for varying depth limits of the call stack. Our results show that the stack depth limit can be significantly reduced while retaining high coverage and that matrix size can be decreased by up to 50%. The metric we used to indicate the difficulty of splitting up the matrix closely resembled the curve for coverage. However, we did not see any significant differences in execution time for lower depth limits.

A dynamic program analysis provides essential information during later phases of an application development. It helps with debugging, profiling, performance optimizations or vulnerability detection. Despite that, support for creating custom dynamic analysis tools, especially in the domain of managed languages, is rather limited. In this thesis, we present two systems to help improve application observability on the Java platform. DiSL is a language accompanied with a framework allowing simple and flexible instrumentation for the dynamic program analysis. DiSL provides high level abstractions to enable quick prototyping even for programmers not possessing a knowledge of Java internals. A skilled analysis developer gains full control over the instrumentation process, thus does not have to worry about unwanted allocations or hidden execution overhead. ShadowVM is a platform that provides isolation between the observed application and the analysis environment. To reduce the amount of possible interactions between the analysis and the application, ShadowVM offloads analysis events out of the context of the application. Even though the isolation is the primary focus of the platform, ShadowVM introduces a number of techniques to stay performance comparable and provide a similar programming model as existing...

Esta tesis propone una metodología de análisis dinámico que mejora el diagnóstico de programas erróneos escritos en el lenguaje Maude. La idea clave es combinar técnicas de verificación de aserciones en tiempo de ejecución con la fragmentación dinámica de trazas de ejecución para detectar automáticamente errores en tiempo de ejecución, al tiempo que se reduce el tamaño y la complejidad de las trazas a analizar. En el caso de violarse una aserción, se infiere automáticamente el criterio de fragmentación, lo que facilita al usuario identificar rápidamente la fuente del error. En primer lugar, la tesis formaliza una técnica destinada a detectar automáticamente eventuales desviaciones del comportamiento deseado del programa (síntomas de error). Esta técnica soporta dos tipos de aserciones definidas por el usuario: aserciones funcionales (que restringen llamadas a funciones deterministas) y aserciones de sistema (que especifican los invariantes de estado del sistema). La técnica de verificación dinámica propuesta es demostrablemente correcta en el sentido de que todos los errores señalados definitivamente delatan la violación de las aserciones. Tras eventuales violaciones de aserciones, se generan automáticamente trazas fragmentadas (es decir, trazas simplificadas pero igualmente precisas) que ayudan a identificar la causa del error. Además, la técnica también sugiere una posible reparación para las reglas implicadas en la generación de los estados erróneos. La metodología propuesta se basa en (i) una notación lógica para especificar las aserciones que se imponen a la ejecución; (ii) una técnica de verificación aplicable en tiempo de ejecución que comprueba dinámicamente las aserciones; y (iii) un mecanismo basado en la generalización (ecuacional) menos general que automáticamente obtiene criterios precisos para fragmentar trazas de ejecución a partir de aserciones falsificadas. Por último, se presenta una implementación de la técnica propuesta en la herramienta de análisis dinámico basado en aserciones ABETS, que muestra cómo es posible combinar el trazado de las propiedades asertadas del programa para obtener un algoritmo preciso de análisis de trazas que resulta útil para el diagnóstico y la depuración de programas. / This thesis proposes a dynamic analysis methodology for improving the diagnosis of erroneous Maude programs. The key idea is to combine runtime assertion checking and dynamic trace slicing for automatically catching errors at runtime while reducing the size and complexity of the erroneous traces to be analyzed (i.e., those leading to states that fail to satisfy the assertions). In the event of an assertion violation, the slicing criterion is automatically inferred, which facilitates the user to rapidly pinpoint the source of the error. First, a technique is formalized that aims at automatically detecting anomalous deviations of the intended program behavior (error symptoms) by using assertions that are checked at runtime. This technique supports two types of user-defined assertions: functional assertions (which constrain deterministic function calls) and system assertions (which specify system state invariants). The proposed dynamic checking is provably sound in the sense that all errors flagged definitely signal a violation of the specifications. Then, upon eventual assertion violations, accurate trace slices (i.e., simplified yet precise execution traces) are generated automatically, which help identify the cause of the error. Moreover, the technique also suggests a possible repair for the rules involved in the generation of the erroneous states. The proposed methodology is based on (i) a logical notation for specifying assertions that are imposed on execution runs; (ii) a runtime checking technique that dynamically tests the assertions; and (iii) a mechanism based on (equational) least general generalization that automatically derives accurate criteria for slicing from falsified assertions. Finally, an implementation of the proposed technique is presented in the assertion-based, dynamic analyzer ABETS, which shows how the forward and backward tracking of asserted program properties leads to a thorough trace analysis algorithm that can be used for program diagnosis and debugging. / Esta tesi proposa una metodologia d'anàlisi dinàmica que millora el diagnòstic de programes erronis escrits en el llenguatge Maude. La idea clau és combinar tècniques de verificació d'assercions en temps d'execució amb la fragmentació dinàmica de traces d'execució per a detectar automàticament errors en temps d'execució, alhora que es reduïx la grandària i la complexitat de les traces a analitzar. En el cas de violar-se una asserció, s'inferix automàticament el criteri de fragmentació, la qual cosa facilita a l'usuari identificar ràpidament la font de l'error. En primer lloc, la tesi formalitza una tècnica destinada a detectar automàticament eventuals desviacions del comportament desitjat del programa (símptomes d'error). Esta tècnica suporta dos tipus d'assercions definides per l'usuari: assercions funcionals (que restringixen crides a funcions deterministes) i assercions de sistema (que especifiquen els invariants d'estat del sistema). La tècnica de verificació dinàmica proposta és demostrablement correcta en el sentit que tots els errors assenyalats definitivament delaten la violació de les assercions. Davant eventuals violacions d'assercions, es generen automàticament traces fragmentades (és a dir, traces simplificades però igualment precises) que ajuden a identificar la causa de l'error. A més, la tècnica també suggerix una possible reparació de les regles implicades en la generació dels estats erronis. La metodologia proposada es basa en (i) una notació lògica per a especificar les assercions que s'imposen a l'execució; (ii) una tècnica de verificació aplicable en temps d'execució que comprova dinàmicament les assercions; i (iii) un mecanisme basat en la generalització (ecuacional) menys general que automàticament obté criteris precisos per a fragmentar traces d'execució a partir d'assercions falsificades. Finalment, es presenta una implementació de la tècnica proposta en la ferramenta d'anàlisi dinàmica basat en assercions ABETS, que mostra com és possible combinar el traçat cap avant i cap arrere de les propietats assertades del programa per a obtindre un algoritme precís d'anàlisi de traces que resulta útil per al diagnòstic i la depuració de programes. / Sapiña Sanchis, J. (2017). Rewriting Logic Techniques for Program Analysis and Optimization [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/94044 / TESIS

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A simple search problem is studied in which a binary n-tuple is to be found in a list, by sequential bit comparisons with cost. The problem can be solved (for small n) using dynamic programming. We show how the “bottom up” part of the algorithm can be organized by means of Formal Concept Analysis.

The complexity associated with development of networked video games creates a need for tools for verifying a consistent player experience. Some networked games achieve consistency through the lockstep protocol, which requires identical execution of sent commands for players to stay synchronised. In this project a method for testing networked multiplayer lockstep games for synchronisation problems related to nondeterministic behaviour is formulated and evaluated. An integrated fuzzing AI is constructed which tries to cause desynchronisation in the tested game and generate data for analysis using log files. Scripts are used for performing semi-automated test runs and parsing the data. The results show that the test system has potential for finding synchronisation problems if the fuzzing AI is used in conjunction with the regular AI in the tested game, but not for finding the origins of said problems. / Komplexiteten förenad med utveckling av nätverksuppkopplade dataspel skapar ett behov av verktyg för att verifiera en konsistent spelarupplevelse. Vissa nätverksspel hålls konsistenta med hjälp av lockstep-protokollet, vilket kräver identisk exekvering av skickade kommandon för att spelarna ska hållas synkroniserade. I detta projekt formuleras och evalueras en metod för att testa om nätverksuppkopplade flerspelarspel lider av synkroniseringsproblem relaterade till ickedeterministiskt beteende. En integrerad fuzzing-AI konstrueras som försöka orsaka desynkronisering i det testade spelet och generera data för analys med hjälp av loggfiler. Skript används för att utföra halvautomatiserade testkörningar och tolka data. Resultaten visar att testsystemet har potential för att hitta synkroniseringsproblem om fuzzing-AI:n används tillsammans med den vanliga AI:n i det testade spelet, men inte för att hitta de bakomliggande orsakerna till dessa problem.