Simone André da Costa Cavalheiro

Specification patterns for properties over reachable states of graph grammars

Essential characteristics of the behavior of a system may be described by properties. These descriptions must be precise and unambiguous to enable verification through (semi-)automated tools. There are many appropriate mathematical languages for writing system requirements, but they are often difficult to be applied by user without a good mathematical background. Patterns for property specifications capture recurring solutions for common problems, simplifying this task. This paper presents specification patterns for properties over reachable states of graph grammars, that is, properties of complex graph structures. This proposal may be used to aid the verification of systems where states are represented as graphs.

Graph Grammars: A Comparison between Verification Methods

Graph grammars are a formal specification language well-suited to applications in which states have a complex topology (involving not only many types of elements, but also different types of relations between them) and in which behaviour is essentially data-driven, that is, events are triggered basically by particular configurations of the state. Many reactive systems are examples of this class of applications, such as protocols for distributed and mobile systems, simulation of biological systems, and many others. Graph grammars can be analysed through model-checking and theorem proving. Each verification technique has arguments for and against its use, but we can say that model-checking and theorem proving are complementary. The main aim of this paper is to present the main existing approaches for the analysis of graph grammars considering each one of these techniques, describing a brief comparative between them.

Discussing the Challenges Related to Deployment of Computational Thinking in Brazilian Basic Education

Computational thinking aims to employ Computer Science foundations to solve problems in different knowledge areas. This paper describes projects related to computational thinking and starts a discussion on the challenges for implementing computational thinking in primary and secondary education in Brazil.

Theorem Proving Graph Grammars: Strategies for Discharging Proof Obligations

One way of developing reliable systems is through the use of Formal Methods. A Graph Grammar specification is visual and based in a simple mechanism of rewriting rules. On the other hand, verification through theorem proving allows the proof of properties for systems with huge (and infinite) state space. There is a previously proposed approach that has allowed the application of theorem proving technique to graph grammars. One of the disadvantages of such an approach (and theorem proving in general) is the specific mathematical knowledge required from the user for concluding the proofs. This paper proposes proof strategies in order to help the developer in the verification process through theorem proving, when adopting graph grammar as specification language.

Theorem proving graph grammars with attributes and negative application conditions

Abstract Graph grammars may be used to formally describe computational systems, modeling the states as graphs and the possible state changes as rules (whose left- and right-hand sides are graphs). The behavior of the system is defined by the application of these rules to the state-graphs. From a practical point of view, the extension of rules to enable description of extra conditions that must be satisfied upon rule application is highly desirable. An example is the specification of negative application conditions, or NACs, that describe situations that prevent the application of a rule. This extension of the basic formalism enhances the expressiveness of rules, generally allowing simpler specifications. Another extension that is fundamental for practical applications is the possibility to use data types, like natural numbers, lists, etc., as attributes of graphical elements (vertices and edges). Attributed graph grammars are well-investigated and used. However, there is a lack of verification techniques for this kind of grammar mainly due to the fact that data types are typically infinite domains, and thus techniques like model checking can not be used directly (without abstraction constructions). The present work provides a theoretical foundation for theorem proving graph grammars with negative application conditions and attributes. This is achieved by generating an event-B model from a graph grammar. Event-B models are composed by sets and axioms to define types, and by states and events to describe behavior. After constructing the event-B model that is semantically equivalent to a graph grammar, properties about reachable states may be proven using the various theorem provers available for event-B in the Rodin platform. This strategy allows the verification of systems with infinite-state spaces without using any kind of approximation.

Sensitivity and Dual Constructions on the Fuzzy f-Xor Class

This paper aims to study the robustness of f-Xorconnectives, in particular of ETP, SP, NS also including its main properties, NS-dual construction and corresponding fuzzy f-Xor implication. Additionally, we obtained some basic results on the pointwise sensitivity of the f-Xor connective ETP, SP, NS, mainly connected with the endpoints of unit interval U. Additionally, we obtained some basic results on the pointwise sensitivity of the f-Xor connective xorTP, SP, NS, mainly connected with the endpoints of unit interval U.

Automatic Translation from UML to Simulink CAAM Using Graph Grammars

The increased amount of software in embedded systems allied to constraints as tight time-to-market and lower costs have motivated the investigation of strategies to manage embedded software design and its complexity. UML and Simulink are considered attractive for the embedded domain, a fact that motivates researchers to aim at finding a way to exploit the benefits of both languages. This paper proposes an automatic translation from UML diagrams to Simulink CAAM models, allowing designers to use UML as modeling language and to use facilities for simulation and code generation based on Simulink.

From UML to SIMULINK CAAM: Formal Specification and Transformation Analysis

UML and Simulink are attractive languages for embedded systems design and modeling. An automatic mapping from UML models to Simulink would be an interesting resource in a seamless design flow, allowing designers to use UML as modeling language for the whole system and at same time to use facilities for code generation based on Simulink. In a previous work, the UML to Simulink translation was prototyped using a Java implementation. In this paper, we present the formal definition of this translation using graph grammars, as well as its automation, which is supported by the AGG system. With the formalization of the metamodels and translation rules, we can guarantee the correctness of the translation. We also illustrate the effectiveness of our methodology by means of a case study.

Using Graph Grammars to Develop Embedded Systems Based on UML Models

UML and Simulink models are widely used in embedded systems design. UML offers proper high-level abstractions for software-oriented models specification, while Simulink allows a better dataflow description. The features of each model motivate the development of proposals unifying and creating mappings between them. This article proposes a formal definition for a translation from UML to a Simulink model, previously proposed, using the graph grammar formalism. This mapping was previously described in natural language and a prototype implemented in Java. The formal definition using graph grammars not only eliminates possible ambiguities in the mapping, but also allows the use of the Groove tool to automate the translation.

Computação na Educação Básica no Brasil: o Estado da Arte

Este artigo apresenta um levantamento de projetos na area do Pensamento Computacional, com foco no ensino fundamental e medio, que tiveram resultados publicados nos principais veiculos de Informatica na Educacao no Brasil. Neste estudo foi identificado que diferentes estrategias tem sido adotadas para a introducao da Computacao na Educacao Basica, destacando-se: Algoritmos e Programacao, Robotica, Jogos, Computacao Desplugada, entre outras. Cada uma das estrategias foi descrita considerando os seguintes aspectos: os conceitos da ciencia da computacao que tem sido abordados, as ferramentas utilizadas, a forma com que a estrategia tem abordado a interdisciplinaridade, a colaboracao e/ou a comunicacao. Ademais, uma descricao estatistica dos trabalhos e realizada, destacando as instituicoes envolvidas nos projetos, o publico alvo, as abordagens e ferramentas utilizadas. O objetivo deste relato e fornecer uma visao geral do que ja foi alcancado na area no Brasil.