Monitoring Complex Processes to Verify System Conformance: A Declarative Rule-Based Framework

Over the last 60 years, computers and software have favoured incredible advancements in every field. Nowadays, however, these systems are so complicated that it is difficult – if not challenging – to understand whether they meet some requirement or are able to show some desired behaviour or property. This dissertation introduces a Just-In-Time (JIT) a posteriori approach to perform the conformance check to identify any deviation from the desired behaviour as soon as possible, and possibly apply some corrections. The declarative framework that implements our approach – entirely developed on the promising open source forward-chaining Production Rule System (PRS) named Drools – consists of three components: 1. a monitoring module based on a novel, efficient implementation of Event Calculus (EC), 2. a general purpose hybrid reasoning module (the first of its genre) merging temporal, semantic, fuzzy and rule-based reasoning, 3. a logic formalism based on the concept of expectations introducing Event-Condition-Expectation rules (ECE-rules) to assess the global conformance of a system. The framework is also accompanied by an optional module that provides Probabilistic Inductive Logic Programming (PILP). By shifting the conformance check from after execution to just in time, this approach combines the advantages of many a posteriori and a priori methods proposed in literature. Quite remarkably, if the corrective actions are explicitly given, the reactive nature of this methodology allows to reconcile any deviations from the desired behaviour as soon as it is detected. In conclusion, the proposed methodology brings some advancements to solve the problem of the conformance checking, helping to fill the gap between humans and the increasingly complex technology.Negli ultimi 60 anni, i computer e i programmi hanno favorito incredibili avanzamenti in ogni campo. Oggigiorno, purtroppo, questi sistemi sono così complicati che è difficile – se non impossibile – capire se soddisfano qualche requisito o mostrano un comportamento o una proprietà desiderati. Questa tesi introduce un approccio a posteriori Just-In-Time (JIT) per effettuare il controllo di conformità ed identificare appena possibile ogni deviazione dal comportamento desiderato, ed eventualmente applicare qualche correzione. Il framework dichiarativo che implementa il nostro approccio – interamente sviluppato su una promettente piattaforma open source di Production Rule System (PRS) chiamata Drools – si compone di tre elementi: 1. un modulo per il monitoraggio basato su una nuova implementazione efficiente di Event Calculus (EC), 2. un modulo generale per il ragionamento ibrido (il primo del suo genere) che supporta ragionamento temporale, semantico, fuzzy e a regole, 3. un formalismo logico basato sul concetto di aspettativa che introduce le Event-Condition-Expectation rules (ECE-rules) per valutare la conformità globale di un sistema. Il framework è anche accompagnato da un modulo opzionale che fornisce Probabilistic Inductive Logic Programming (PILP). Spostando il controllo di conformità da dopo l’esecuzione ad appena in tempo, questo approccio combina i vantaggi di molti metodi a posteriori e a priori proposti in letteratura. Si noti che, se le azioni correttive sono fornite esplicitamente, la natura reattiva di questo metodo consente di conciliare le deviazioni dal comportamento desiderato non appena questo viene rilevato. In conclusione, la metodologia proposta introduce alcuni avanzamenti per risolvere il problema del controllo di conformità, contribuendo a colmare il divario tra l’uomo e la tecnologia, sempre più complessa

Planning while Believing to Know

Over the last few years, the concept of Artificial Intelligence (AI) has become essential in our daily life and in several working scenarios. Among the various branches of AI, automated planning and the study of multi-agent systems are central research fields. This thesis focuses on a combination of these two areas: that is, a specialized kind of planning known as Multi-agent Epistemic Planning. This field of research is concentrated on all those scenarios where agents, reasoning in the space of knowledge/beliefs, try to find a plan to reach a desirable state from a starting one. This requires agents able to reason about her/his and others’ knowledge/beliefs and, therefore, capable of performing epistemic reasoning. Being aware of the information flows and the others’ states of mind is, in fact, a key aspect in several planning situations. That is why developing autonomous agents, that can reason considering the perspectives of their peers, is paramount to model a variety of real-world domains. The objective of our work is to formalize an environment where a complete characterization of the agents’ knowledge/beliefs interactions and updates are possible. In particular, we achieved such a goal by defining a new action-based language for Multi-agent Epistemic Planning and implementing epistemic planners based on it. These solvers, flexible enough to reason about various domains and different nuances of knowledge/belief update, can provide a solid base for further research on epistemic reasoning or real-base applications. This dissertation also proposes the design of a more general epistemic planning architecture. This architecture, following famous cognitive theories, tries to emulate some characteristics of the human decision-making process. In particular, we envisioned a system composed of several solving processes, each one with its own trade-off between efficiency and correctness, which are arbitrated by a meta-cognitive module

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Ontology-Supported Scaffolding for System Safety Analysis

System Safety Analysis is a valuable task used when trying to ensure that any thing that can be represented with the systems-model does not behave in some manner that is undesirable to the stakeholders in that system. It's a creative task, with no known correct solution, with limited tool support. This thesis investigates the possibility of providing support to analysts undertaking this task through the use of ontology and pedagogy in an artificially intelligent tool. An ontology to capture the system-model as understood by System-Theoretic Accident Model and Processes (STAMP) was authored, building on an existing set-theoretic representation. This required the authoring of underlying ontology-modules, including one for Control Systems and one to capture sufficient information for use with Situation Calculus. Together these capture information to be used in reasoning about system behaviour. During System Safety Analysis a user extends this ontology to model their system, and the intelligent support tool interprets it to offer its advice. The intelligent support tool uses Contingent Scaffolding to tailor its support to the user, this pedagogical strategy was chosen as it's been shown to enable the learner to produce a better quality product than they would be capable of alone. Contingent Scaffolding depends upon knowledge of past behaviour of the learner so that interventions can be pitched at the correct level for the learner. Typically ontology authoring tools use a synchronic view of the ontology, and so don't capture the required history. This tool uses Situation Calculus to capture a diachronic view of the ontology such that the history of authorship can be reasoned with to apply the Contingent Scaffolding framework defined herein. To evaluate the practicability of this approach the ontology and scaffolding were implemented in software. This surfaced an issue with the inability to inverse dependencies in Prolog, which was important to make the tools reuseable and shareable. These were overcome by Protocols provided in Logtalk. The code was then applied to other domains, such as robotics planning by a third-party, demonstrating generalisability of the intelligent support tool. A user study was conducted to evaluate the effectiveness of the intelligent support tool, in which novices undertook a System Safety Analysis. The tool was able to effectively provide support where definitions were missed and additional patterns of behaviour were identified that are indicitive of the user needing support. The thesis makes a number of contributions including: a systems ontology with a focus on capturing hypothetical and realised behaviour, a formal definition of a contingent scaffolding framework that can be used with ill-defined tasks, and the use of dependency inversion in Prolog to enable sharing of libraries. The primary contribution is in the use of a diachronic view of ontology authoring to provide support, which has been successfully exploited and has scope for providing a platform for many more applications

Introducing norms into practical reasoning agents

As distributed electronic systems grow to include thousands of components, from grid to peer-to-peer nodes, from (Semantic) Web services to web-apps to computation in the cloud, governance of such systems is becoming a real challenge. Modern approaches ensuring appropriate individual entities' behaviour in distributed systems, which comes from multi-agent systems (MAS) research, use norms (or regulations or policies) and/or communication protocols to express a different layer of desired or undesired states. From the individuals perspective, an agent needs to be able to function in an environment where norms act as behavioural restrictions or guidelines as to what is appropriate, not only for the individual but also for the community. In the literature the concept of norms has been defined from several perspectives: as a rule or standard of behaviour shared by members of a social group, as an authoritative rule or standard by which something is judged, approved or disapproved, as standards of right and wrong, beauty and ugliness, and truth and falsehood, or even as a model of what should exist or be followed, or an average of what currently does exist in some context. Currently there exist in the literature: 1) some treatments that formally connect the deontic aspects of norms with their operationalisation; 2) some treatments that properly distinguish between abstract norms and their (multiple) instantiations at runtime; 3) little work that formalises the operational semantics in a way that ensures flexibility in their translation to actual implementations while ensuring unambiguous interpretations of the norms; 4) little work that is suitable for both institutional-level norm monitoring and individual agent norm-aware reasoning to ensure that both are aligned; 5) few works that explore how the norms may affect the decision making process of an agent when the process includes planning mechanisms at runtime for means-ends reasoning. However, currently there is no work that includes both a formalism and an implementation covering 1-5 altogether. This thesis presents work towards the above five areas. We give a proposal to bridge the gap between a single norm formalisation and the actual mechanisms used for norm-aware planning, in order to create a normative practical reasoning mechanism. One way to do this is by reducing deontic-based norm definitions to temporal logic formulas which, in turn, can be translated into planning operational semantics. Based on these semantics, we create a mechanism to support practical normative reasoning that can be used by agents to produce and evaluate their plans. We construct a norm-oriented agent that takes into consideration operationalised norms during the plan generation phase, using them as guidelines to decide the agents future action path. To make norms influence plan generation, our norm operational semantics is expressed as an extension of the planning domain, acting as a form of temporal restrictions over the trajectories (plans) computed by the planner. We consider two approaches to do so. One implementing the semantics by using planning with constraints through paths and the other by directly translating the norms into domain knowledge to be included into the planning domain. We explore a scenario based on traffic laws in order to demonstrate the usability of our proposal. We also show how our normative frameworks are successfullyintegrated into an existing BDI agent implementation, 2APL. For each approach taken, we present quantitative experimental results and illustrate the opportunities for further research.La gestión de sistemas electrónicos distribuidos se está convirtiendo en un auténtico reto a medida que dichos sistemas crecen incluyendo múltiples componentes, desde nodos grid a peer-to-peer, servicios de la Web semántica, aplicaciones web o computación en la nube. Los enfoques modernos que aseguran un comportamiento adecuado de las entidades individuales en sistemas distribuidos, y que provienen de la investigación en sistemas multi-agentes (MAS), utilizan normas (o regulaciones o políticas) para expresar un nivel diferente de estados deseados o no deseados. Desde la perspectiva del individuo, un agente necesita poder funcionar en un entorno donde las normas actúen como restricciones o directrices de comportamiento respecto a lo que es apropiado,no únicamente para el individuo sino para la comunidad en su conjunto. En la literatura el concepto de norma se ha definido desde varias perspectivas: como una regla o estándar de comportamiento compartida por los miembros de un grupo social, como estándar de lo correcto o incorrecto, belleza o fealdad, o incluso, como un modelo que debería existir o ser seguido. En la actualidad se pueden encontrar en la literatura: 1) trabajos que conectan formalmente los aspectos deónticos de las normas con su operacionalización; 2) trabajos que distinguen adecuadamente entre normas abstractas y sus (múltiples) instanciaciones en tiempo de ejecución; 3) algún ejemplo que formaliza las semánticas operacionales de manera que se asegura la flexibilidad en su traducción a implementaciones garantizando a su vez interpretaciones no ambiguas de las normas; 4) algún trabajo que se adecúa tanto a la monitorización de normas a nivel institucional como al razonamiento basado en normas a nivel de los agentes individuales y que asegura que ambos están alineados; 5) algún trabajo que explora como las normas pueden afectar al proceso de toma de decisiones de un agente cuando el proceso incluye mecanismos de planificación en tiempo real para un razonamiento medios-fines. Sin embargo, actualmente no existe ningún enfoque que incluya formalismos e implementaciones abordando los 5 puntos al mismo tiempo. La presente tesis propone contribuciones en las cinco áreas mencionadas. Se presenta una propuesta para establecer un enlace entre la formalización de una norma y los mecanismos utilizados en la planificación basada en normas con el objetivo de crear un mecanismo de razonamiento práctico normativo. Una forma de conseguirlo es mediante la reducción de las definiciones de normas basadas en deóntica a fórmulas de lógica temporal que, a su vez, pueden ser traducidas a semánticas operacionales de planificación. Basándose en estas semánticas, se ha creado un mecanismo para dar soporte al razonamiento normativo práctico que puede ser utilizado por los agentes para producir y evaluar sus planes. Se ha construido un agente orientado a normas que tiene en consideración las normas operacionalizadas durante la fase de generación de planes, utilizándolas como directrices para decidir el futuro curso de acción del agente. Nuestras semánticas operacionales de normas se expresan como una extensión del dominio de la planificación, actuando como una forma de restricciones temporales sobre las trayectorias (planes) computadas por el planificador. Se han considerado dos enfoques para realizarlo. Uno, implementando las semánticas utilizando planificación con restricciones a través de caminos y otro, traduciendo directamente las normas en conocimiento del dominio que se incluirá en el dominio de planificación. Se explora un escenario basado en normas de circulación de tráfico para demostrar la usabilidad de nuestra propuesta. Se mostrará también como nuestro marco normativo se integra satisfactoriamente en una implementación existente de agentes BDI, 2APL. Para cada enfoque considerado, se presentan resultados experimentales cuantitativos y se ilustran las oportunidades para futuros trabajos de investigación.A mesura que els sistemes electrònics distribuïts creixen per incloure milers de components,des de nodes grid a peer-to-peer fins a serveis de la Web semàntica, aplicacions web o computació al núvol, la gestió d’aquests sistemes s’està convertint en un autèntic repte. Els enfocs moderns que asseguren el comportament apropiat de lesentitats individuals en sistemes distribuïts, que prové de la recerca en sistemes multiagents, utilitzen normes (o regulacions o polítiques) i/o protocols de comunicació perexpressar una capa diferent d’estats desitjats o no desitjats. Des de la perspectiva de l’individu, un agent necessita poder funcionar en un entorn on les normes actuïn coma restriccions de comportament o guies respecte al que és apropiat, no només per al individu sinó per a la comunitat.En la literatura el concepte de normes s’ha tractat des de diferents perspectives: com una regla o estàndard de comportament compartida pels membres d’un grup social, com una regla o estàndard autoritari pel qual alguna cosa és jutjada, aprovada o desaprovada,com estàndard del correcte i del incorrecte, bellesa i lletjor, veritat i falsedat, o inclús com un model del que hauria d’existir o ser seguit, o com una mitjana del que actualment existeix en un context donat. Actualment trobem en la literatura:1) alguns tractaments que connecten formalment els aspectes deòntics de les normes amb la seva operacionalització; 2) alguns tractaments que distingeixen adequadament entre normes abstractes i les seves (múltiples) instanciacions en temps real; 3) alguns exemples que formalitzen les semàntiques operacionals de manera que asseguren flexibilitaten la seva traducció a implementacions garantint interpretacions no ambigües de les normes; 4) alguns treballs adequats per a la monitorització de normes a nivell institucional i per al raonament basat en normes en agents individuals assegurant que ambdós estan alineats; 5) alguns treballs que exploren com les normes poden afectar el procés de presa de decisions d’un agent quan el procés inclou mecanismes de planificació en temps real per a raonament mitjans-finalitats. D’altra banda, actualment noexisteix cap enfoc que inclogui formalismes i implementacions cobrint els punts 1-5 a la vegada.Aquesta tesi presenta contribucions en les cinc àrees esmentades. Presentem una proposta per establir un enllaç entre la formalització d’una norma i els mecanismes emprats en la planificació basada en normes per tal de crear un mecanisme de raonament pràctic normatiu. Una manera d’aconseguir-ho és reduint les definicions de normes deòntiques a fórmules de lògica temporal les quals poden ser traduïdes asemàntiques de planificació operacional. Basant-nos en aquestes semàntiques, hem creat un mecanisme per donar suport al raonament normatiu pràctic que pot ser emprat per agents per produir i avaluar els seus plans. Hem construït un agent orientat a normes que pren en consideració durant la fase de generació de plans les normes operacionalitzades, utilitzant-les com a guia per decidir el futur curs d’acció de l’agent.Per tal de fer que les normes influenciïn la generació de plans, les nostres semàntiques operacionals de normes s’expressen com una extensió del domini de la planificació,actuant com una mena de restriccions temporals sobre les trajectòries (plans) computadespel planificador. Considerem dos enfocs per dur-ho a terme. Un implementant les semàntiques emprant planificació amb restriccions per mitjà de camins i l’altre traduint directament les normes en coneixement del domini a ser inclòs en el domini de planificació. Explorem un escenari basat en les normes de circulació de tràfic per demostrar la usabilitat de la nostra proposta. Mostrarem també com el nostre marc normatiu s’integra satisfactòriament en una implementació existent d’agentBDI, 2APL. Per cada enfoc considerat, presentem resultats experimentals quantitatius i il.lustrem les oportunitats per treballs de recerca futurs

SmartPM: automatic adaptation of dynamic processes at run-time

The research activity outlined in this thesis is devoted to define a general approach, a concrete architecture and a prototype Process Management System (PMS) for the automated adaptation of dynamic processes at run-time, on the basis of a declarative specification of process tasks and relying on well-established reasoning about actions and planning techniques. The purpose is to demonstrate that the combination of procedural and imperative models with declarative elements, along with the exploitation of techniques from the field of artificial intelligence (AI), such as Situation Calculus, IndiGolog and automated planning, can increase the ability of existing PMSs of supporting dynamic processes. To this end, a prototype PMS named SmartPM, which is specifically tailored for supporting collaborative work of process participants during pervasive scenarios, has been developed. The adaptation mechanism deployed on SmartPM is based on execution monitoring for detecting failures at run-time, which does not require the definition of the adaptation strategy in the process itself (as most of the current approaches do), and on automatic planning techniques for the synthesis of the recovery procedure

Vers une plateforme dédiée à la composition automatique et l'exécution de services : Applications E-Tourisme

Recently, distributed computing systems based on context awareness have been proposing in several domains such as healthcare, logistics and tourism. The study described in this thesis is a part of a broader project of E-Tourism system that provides nomad user, context-aware personalized services. The work of this thesis focuses on the issues raised by web service composition and execution. Web service composition brings benefits of reusing existing services to synthesize the new resulting service that meets users needs. The way to create web service composition normally happens at design time, but this limits choices of services. This thesis presents a novel approach of automated web service composition and execution framework. Our approach aims to compose service operations that fulfill mobile users' requirements expressed in propositional logic and execute the resulting service based on aggregating multi service components. In the proposed framework, we have introduced our planning algorithm based on abstract goal states to search and connect to service operations, by mean of service operation annotations, for an abstract plan. The abstract plan is expected for workflow model of sequencing, paralleling and conditioning among service operations. However, the generated workflow is not in an executable form, this is why we perform the transformation of the workflow into an executable business process. To achieve the business process execution, we defined context based BPMN model for mapping the abstract plan to BPMN semantics. We also propose a new validation algorithm and exploited planning-as-model-checking approach to validate the semantic BPMN model whether it is Well-formed and Well-defined BPMN process. Finally, we implemented the automated service composition and execution framework system in Java platform as a proof of concept. We developed the logical composition and, transformation and validation BPMN algorithms written in Prolog. We have integrated these algorithms into the whole system. From the perspective, we plan to extend our current work and take into account more complex user's scenarios that explicitly and implicitly express other pattern controls and we will also consider the scenarios required for stateful web servicesLes systèmes de services contextualisés ont connu un grand essor ces dernières années dans des domaines variés tels que la santé, la logistique ou bien le tourisme. Cette thèse s'intègre dans un projet plus global, nommé E-Tourism, qui vise à réaliser une plateforme de fourniture de services sensibles au contexte à des utilisateurs en situation de mobilité. Le travail de cette thèse se focalise sur la problématique de composition de services web et de leur exécution. La composition de services web permet la réutilisation de services existants afin d'en faire une synthèse répondant au besoin de l'utilisateur. Cette composition se fait en général au niveau de la phase conceptuelle ce qui limite le choix de services potentiels. Cette thèse présente une nouvelle approche de la composition de services Web automatisé et une plateforme d'exécution. Notre approche vise à composer les opérations de services qui répondent aux besoins des utilisateurs mobiles exprimées dans une logique propositionnelle et exécuter le service composé en agrégeant plusieurs services composants. Nous avons proposé une plateforme d'exécution de services et nous avons introduit un nouvel algorithme de planification intégré à cette plateforme. Nous avons défini un contexte basé sur le modèle BPMN. Afin de valider notre modèle sémantique nous avons utilisé une approche de type « model-checking » . Enfin, nous avons réalisé un prototype sous forme d'une plateforme de composition de services et d'exécution automatique en Java. Nous avons implémenté les règles d'inférence et les modèles BPMN en prolog. Enfin, nous avons intégré ces algorithmes dans l'ensemble du système. En perspectives, nous prévoyons d'étendre notre travail actuel et prendre en compte des scénarios plus complexes nécessitant des services web dynamiques