Foss & Connelly\u27s Stages Going to the Geysers.

The stereograph features a black and white image of a line of three stage coaches traveling down a path surrounded by rough terrane. The image is mounted on a yellow card with rounded edges.https://scholarsjunction.msstate.edu/fvw-photographs/1407/thumbnail.jp

Foss & Connelly\u27s Stages Going to the Geysers.

The stereograph features a black and white image of a line of three stage coaches traveling down a path surrounded by rough terrane. The image is mounted on a yellow card with rounded edges.https://scholarsjunction.msstate.edu/fvw-artifacts/1721/thumbnail.jp

Exploiting Behavioral Hierarchy for Efficient Model Checking

Inspired by the success of model checking in hardware and protocol verification, model checking techniques for software have been the focus of a lot of research in the last few years [5,3,2,6]. Model checking can be applied only to relatively small models due to its inherently high computational requirements, and there are two complementary trends to address scalability. The model extraction approach, exemplified by projects such as Bandera [6] and SLAM [3], involves constructing inputs to model checkers by abstracting programs written in languages such as C and Java. The model-based design approach, exemplified by modeling notations such as Statecharts [7], promotes design using high-level models that are compiled into code. Our research agenda is to develop model checking techniques for model-based design of software. Modern software design languages promote hierarchy as one of the key constructs for structuring complex specifications. The input language to our model checker is based on hierarchic reactive modules [1]. This choice was motivated by the fact that, unlike STATECHARTS and other languages, in hierarchic reactive modules, the notion of hierarchy is semantic with an observational trace-based semantics and a notion of refinement with assume-guarantee rules. The first contribution of this paper is the Hermes toolkit that implements hierarchic reactive modules. Our implementation has a visual front-end and XML-based back-end, consistent with modern software design tools, and is in Java. There are two basic techniques for reachability analysis. Enumerative model checkers such as SPIN [8] perform an on-the-fly exploration of the state-space using a depth-first search, while symbolic model checkers such as SMV [9] perform a breadth-first search by manipulating sets of states, rather than individual states, encoded typically by ordered binary (or multi-valued) decision diagrams. Since the two approaches are incomparable, and have been shown to be successful, Hermes supports both enumerative and symbolic reachability analysis. In this paper, we report progress on exploiting the structuring information in the behavioral hierarchy of the input model to speed up the exploration of reachable state-space of the model for both the approaches. More information about the tool is available at http://www.cis.upenn.edu/sdrl/hermes

Uma abordagem para o ensino de produtos notáveis em uma classe inclusiva: o caso de uma aluna com deficiência visual

Acompanha: Produtos notáveisThe research has as its theme the Math teaching and the inclusion of visually challenged students in regular education. This is a research with qualitative approach using a study case as strategy. It aims at the development of didactic-methodological procedures that enable visually challenged included in regular education, as well as other students, to appropriate of mathematical knowledge. This study was based on the socio-historical current for the development of a pedagogical intervention in an 8th grade classroom of a secondary public school in the countryside of Paraná, which had a visually challenged student included. In the intervention were approached concepts of Geometry, Algebra, Values and Measurements such as Area, Perimeter and Volume, with inference of Notable Products. The developed activities were grounded in the Theory of Piotr Yakovlevich Galperin (2009) for the formation of concepts. For the activities development was elaoreted the teaching material “Notable Products” with adaptations for visually challenged students. After the activities implementation it was realized that it is possible to teach Mathematics to visually challenged students with others in a classroom that everyone, regardless of their limitations, are able to elaborate necessary concepts for their autonomy and citizenship practice.Esta pesquisa apresenta como tema o ensino de Matemática e a inclusão de alunos deficientes visuais no ensino regular. Trata-se de uma pesquisa com abordagem qualitativa, utilizando-se do estudo de caso como estratégia. Seu objetivo é o desenvolvimento de procedimentos didático - metodológicos que possibilitem aos deficientes visuais inclusos no ensino regular a apropriação dos conhecimentos matemáticos, assim como os demais alunos. Fundamentou-se nos pressupostos da corrente sócio – histórica para o desenvolvimento de uma intervenção pedagógica em uma turma do oitavo ano do Ensino Fundamental de um colégio público do interior do Paraná, que contava com uma aluna deficiente visual inclusa. Na intervenção foram abordados conceitos matemáticos em Geometria, Álgebra e Grandezas e Medidas como Área, Perímetro e Volume, com inferência aos Produtos Notáveis. As atividades desenvolvidas foram elaboradas fundamentadas na Teoria de Piotr Yakovlevich Galperin (2009) para a formação de conceitos. Para o desenvolvimento das atividades elaborou-se o material didático “Produtos Notáveis”, com adaptações para alunos com deficiência visual. Após a aplicação das atividades, percebeu-se que é possível ensinar Matemática, aos alunos com deficiência visual, juntamente com os demais em uma turma e que todos, independente das limitações, são capazes de elaborar conceitos necessários para a autonomia e o exercício da cidadania

Intersection and Rotation of Assumption Literals Boosts Bug-Finding

SAT-based techniques comprise the state-of-the-art in functional verification of safety-critical hardware and software, including IC3/PDR-based model checking and Bounded Model Checking (BMC). BMC is the incontrovertible best method for unsafety checking, aka bug-finding. Complementary Approximate Reachability (CAR) and IC3/PDR complement BMC for bug-finding by detecting different sets of bugs. To boost the efficiency of formal verification, we introduce heuristics involving intersection and rotation of the assumption literals used in the SAT encodings of these techniques. The heuristics generate smaller unsat cores and diverse satisfying assignments that help in faster convergence of these techniques, and have negligible runtime overhead. We detail these heuristics, incorporate them in CAR, and perform an extensive experimental evaluation of their performance, showing a 25% boost in bug-finding efficiency of CAR.We contribute a detailed analysis of the effectiveness of these heuristics: their influence on SAT-based bug-finding enables detection of different bugs from BMCbased checking. We find the new heuristics are applicable to IC3/PDR-based algorithms as well, and contribute a modified clause generalization procedure

Solving Parallel Equations with BALM-II

In this report we describe how to solve parallel language equations over regular languages / automata and finite state machines (FSMs), using the software package BALM-II. The original version of BALM could solve equations only with respect to synchronous composition; we extended the original code to solve also equations with respect to parallel composition, adding new commands and procedures. The new version of BALM is called BALM-II, of which this document provides a user's manual. Finally, as an important application, we describe how to synthesize protocol converters with BALM-II

Software Model Checking with Explicit Scheduler and Symbolic Threads

In many practical application domains, the software is organized into a set of threads, whose activation is exclusive and controlled by a cooperative scheduling policy: threads execute, without any interruption, until they either terminate or yield the control explicitly to the scheduler. The formal verification of such software poses significant challenges. On the one side, each thread may have infinite state space, and might call for abstraction. On the other side, the scheduling policy is often important for correctness, and an approach based on abstracting the scheduler may result in loss of precision and false positives. Unfortunately, the translation of the problem into a purely sequential software model checking problem turns out to be highly inefficient for the available technologies. We propose a software model checking technique that exploits the intrinsic structure of these programs. Each thread is translated into a separate sequential program and explored symbolically with lazy abstraction, while the overall verification is orchestrated by the direct execution of the scheduler. The approach is optimized by filtering the exploration of the scheduler with the integration of partial-order reduction. The technique, called ESST (Explicit Scheduler, Symbolic Threads) has been implemented and experimentally evaluated on a significant set of benchmarks. The results demonstrate that ESST technique is way more effective than software model checking applied to the sequentialized programs, and that partial-order reduction can lead to further performance improvements.Comment: 40 pages, 10 figures, accepted for publication in journal of logical methods in computer scienc

Artificial Intelligence

Contains research objectives and reports on five research projects.Computation Center, M.I.T

Seasonal Cholera from Multiple Small Outbreaks, Rural Bangladesh

Clinical and environmental Vibrio cholerae organisms collected from February 2004 through April 2005 were systematically isolated from 2 rural Bangladeshi locales. Their genetic relatedness was evaluated at 5 loci that contained a variable number of tandem repeats (VNTR). The observed minimal overlap in VNTR patterns between the 2 communities was consistent with sequential, small outbreaks from local sources