jsFLAP: A JavaScript Formal Languages and Automata Package for Computer Science Education

Visualization and simulation software serves an important role in education, especially in the education of abstract topics. The field of computational theory, and specifically the topics of formal languages and finite automata are well suited to visualization. When done properly, this improves the learning experience for both students and educators. The JavaScript Formal Languages and Automata Package (jsFLAP) was created to facilitate the construction and simulation of different types of finite state automata. Following best practices for visualization design, jsFLAP was designed to be accessible and easy to use. It aims to reduce frustration for students, allowing them to focus on engaging directly with the underlying concepts, and to require as little technological overhead as possible for instructors wishing to integrate it into their curriculum. In doing this, jsFLAP can serve an important role in the education of computing theory, replacing existing automata construction tools or reaching audiences that those tools could not.Keywords: computer science, education, visualization, formal languages, automat

Proceedings of the Second Program Visualization Workshop, 2002

The Program Visualization Workshops aim to bring together researchers who design and construct program visualizations and, above all, educators who use and evaluate visualizations in their teaching. The first workshop took place in July 2000 at Porvoo, Finland. The second workshop was held in cooperation with ACM SIGCSE and took place at HornstrupCentret, Denmark in June 2002, immediately following the ITiCSE 2002 Conference in Aarhus, Denmark

OCaml-Flat on the Ocsigen framework

Formal Languages and Automata Theory are important and fundamental topics in Computer Science. Due to their rigorous and formal characteristics, learning these becomes demanding. An important support for the assimilation of concepts is the possibility of interactively visualizing concrete examples of these computational models, thus facilitating their understanding. There are many tools available, but most are not complete or do not fully support the interactive aspect. This project aims at the development of an interactive web tool in Portuguese to help understand, in an assisted and intuitive way, the concepts and algorithms in question, watching them work step-by-step, through typical examples pre-loaded or built by the user (an original aspect of our platform). The tool should therefore enable the creation and edition of an automaton or a regular expression, as well as execute the relevant classical algorithms such as word acceptance, model conversions, etc. Another important feature is that the tool has a clean design, in which everything is well organized and it is also extensible so that new features can be easily added later. This tool uses the Ocsigen Framework because it provides the development of complete and interactive web tools written in OCaml, a functional language with a strong type checking system and therefore perfectly suitable for a web page without errors. Ocsigen was also chosen because it allows the creation of dynamic pages with a singular clientserver system. This document introduces the development of the tool, its design aspects that enable showing different conversions and processes as well as the development of the several functionalities related to the mechanisms already presented

Reorganización de las prácticas de compiladores para mejorar el aprendizaje de los estudiantes

La parte práctica de asignaturas como Compiladores o Procesadores de Lenguajes (las trataremos como la misma en el resto de la comunicación) suele ser bastante costosa, ya que requiere cierto grado de planificación y continuidad en el trabajo de los estudiantes y las herramientas utilizadas no tienen una conexión clara con los fundamentos teóricos. Nuestra propuesta estructura estas sesiones prácticas en tres tipos: las que se encargan de enlazar teoría y práctica, las que introducen a los estudiantes las herramientas de generación de compiladores y la final donde se desarrolla un compilador de cierta complejidad. Con este enfoque hemos mejorado el porcentaje de éxito en la parte práctica hasta un 86%.Peer Reviewe

A Learning System for a Computational Science Related Topic

AbstractComputational science is an interdisciplinary field in which mathematical models combined with scientific computing methods are used to study systems of real-world problems. One of such mathematical models is automata theory. This paper introduces a learning system for automata theory. The learning system is a combination of java and robots technologies. Learners can build their own automaton graphically in the systems’ interface, and then pass it to the robot, which can then simulate the automaton transitions. Learners can learn by observing the robot's motion. A preliminary evaluation shows the effectiveness of the system in classroom

Reorganización de las prácticas de compiladores para mejorar el aprendizaje de los estudiantes

La parte práctica de asignaturas como Compiladores o Procesadores de Lenguajes (las trataremos como la misma en el resto de la comunicación) suele ser bastante costosa, ya que requiere cierto grado de planificación y continuidad en el trabajo de los estudiantes y las herramientas utilizadas no tienen una conexión clara con los fundamentos teóricos. Nuestra propuesta estructura estas sesiones prácticas en tres tipos: las que se encargan de enlazar teoría y práctica, las que introducen a los estudiantes las herramientas de generación de compiladores y la final donde se desarrolla un compilador de cierta complejidad. Con este enfoque hemos mejorado el porcentaje de éxito en la parte práctica hasta un 86%.Este trabajo se ha financiado con el proyecto TIN2008-04103 del Ministerio de Ciencia y Tecnología del Reino de España

Tools and Environments

Teaching and learning how to build software are central aspects of computing education, and the tools which we use to support this are themselves a focus of research and innovation. This chapter considers tools designed or predominately used for education; from software development environments to automatic assessment tools, visualization, and educational games platforms. It looks at not just the history and state-of-the-art of these tools, but also at the challenges and opportunities in researching with and about them

Security policy architecture for web services environment

An enhanced observer is model that observes behaviour of a service and then automatically reports any changes in the state of the service to evaluator model. The e-observer observes the state of a service to determine whether it conforms to and obeys its intended behaviour or policy rules. E-observer techniques address most problems, govern and provide a proven solution that is re-usable in a similar context. This leads to an organisation and formalisation policy which is the engine of the e-observer model. Policies are used to refer to specific security rules for particular systems. They are derived from the goals of management that describe the desired behaviour of distributed heterogeneous systems and networks. These policies should be defended by security which has become a coherent and crucial issue. Security aims to protect these policies whenever possible. It is the first line of protection for resources or assets against events such as loss of availability, unauthorised access or modification of data. The techniques devised to protect information from intruders are general purpose in nature and, therefore, cannot directly enforce security that has no universal definition, the high degree of assurance of security properties of systems used in security-critical areas, such as business, education and financial, is usually achieved by verification. In addition, security policies express the protection requirements of a system in a precise and unambiguous form. They describe the requirements and mechanisms for securing the resources and assets between the sharing parties of a business transaction. However, Service-Oriented Computing (SOC) is a new paradigm of computing that considers "services" as fundamental elements for developing applications/solutions. SOC has many advantages that support IT to improve and increase its capabilities. SOC allows flexibility to be integrated into application development. This allows services to be provided in a highly distributed manner by Web services. Many organisations and enterprises have undertaken developments using SOC. Web services (WSs) are examples of SOC. WSs have become more powerful and sophisticated in recent years and are being used successfully for inter-operable solutions across various networks. The main benefit of web services is that they use machine-to-machine interaction. This leads initially to explore the "Quality" aspect of the services. Quality of Service (QoS) describes many techniques that prioritise one type of traffic or programme that operates across a network connection. Hence, QoS has rules to determine which requests have priority and uses these rules in order to specify their priority to real-time communications. In addition, these rules can be sophisticated and expressed as policies that constrain the behaviour of these services. The rules (policies) should be addressed and enforced by the security mechanism. Moreover, in SOC and in particular web services, services are black boxes where behaviour may be completely determined by its interaction with other services under confederation system. Therefore, we propose the design and implementation of the “behaviour of services,” which is constrained by QoS policies. We formulate and implement novel techniques for web service policy-based QoS, which leads to the development of a framework for observing services. These services interact with each other by verifying them in a formal and systematic manner. This framework can be used to specify security policies in a succinct and unambiguous manner; thus, we developed a set of rules that can be applied inductively to verify the set of traces generated by the specification of our model’s policy. These rules could be also used for verifying the functionality of the system. In order to demonstrate the protection features of information system that is able to specify and concisely describe a set of traces generated, we subsequently consider the design and management of Ponder policy language to express QoS and its associated based on criteria, such as, security. An algorithm was composed for analysing the observations that are constrained by policies, and then a prototype system for demonstrating the observation architecture within the education sector. Finally, an enforcement system was used to successfully deploy the prototype’s infrastructure over Web services in order to define an optimisation model that would capture efficiency requirements. Therefore, our assumption is, tracing and observing the communication between services and then takes the decision based on their behaviour and history. Hence, the big issue here is how do we ensure that some given security requirements are satisfied and enforced? The scenario here is under confederation system and based on the following: System’s components are Web-services. These components are black boxes and designed/built by various vendors. Topology is highly changeable. Consequently, the main issues are: • The proposal, design and development of a prototype of observation system that manages security policy and its associated aspects by evaluating the outcome results via the evaluator model. • Taming the design complexity of the observation system by leaving considerable degrees of freedom for their structure and behaviour and by bestowing upon them certain characteristics, and to learn and adapt with respect to dynamically changing environments.Saudi Arabian Cultural Burea

Quantitative Analysis of Information Leakage in Probabilistic and Nondeterministic Systems

This thesis addresses the foundational aspects of formal methods for applications in security and in particular in anonymity. More concretely, we develop frameworks for the specification of anonymity properties and propose algorithms for their verification. Since in practice anonymity protocols always leak some information, we focus on quantitative properties, which capture the amount of information leaked by a protocol. The main contribution of this thesis is cpCTL, the first temporal logic that allows for the specification and verification of conditional probabilities (which are the key ingredient of most anonymity properties). In addition, we have considered several prominent definitions of information-leakage and developed the first algorithms allowing us to compute (and even approximate) the information leakage of anonymity protocols according to these definitions. We have also studied a well-known problem in the specification and analysis of distributed anonymity protocols, namely full-information scheduling. To overcome this problem, we have proposed an alternative notion of scheduling and adjusted accordingly several anonymity properties from the literature. Our last major contribution is a debugging technique that helps on the detection of flaws in security protocols.Comment: thesis, ISBN: 978-94-91211-74-