A Framework for the Flexible Integration of a Class of Decision Procedures into Theorem Provers

The role of decision procedures is often essential in theorem proving. Decision procedures can reduce the search space of heuristic components of a prover and increase its abilities. However, in some applications only a small number of conjectures fall within the scope of the available decision procedures. Some of these conjectures could in an informal sense fall ‘just outside’ that scope. In these situations a problem arises because lemmas have to be invoked or the decision procedure has to communicate with the heuristic component of a theorem prover. This problem is also related to the general problem of how to exibly integrate decision procedures into heuristic theorem provers. In this paper we address such problems and describe a framework for the exible integration of decision procedures into other proof methods. The proposed framework can be used in different theorem provers, for different theories and for different decision procedures. New decision procedures can be simply ‘plugged-in’ to the system. As an illustration, we describe an instantiation of this framework within the Clam proof-planning system, to which it is well suited. We report on some results using this implementation

The effect of collective effficacy on teachers' technology acceptance

This investigation of teachers computer use prompted by a 1999 Provincial Assessment finding that students were performing below Provincial expectations in use of the World Wide Web / Internet and identification of teachers as students greatest source of computer knowledge. It was found that the majority of teachers have the necessary knowledge and skills to use computers in the classroom, but teachers predominantly used computers for personal and general purposes. It was also found that teachers represent a large source of influence on their colleagues’ computer knowledge and skills. This influence, defined through the construct of collective efficacy, was found to differ between schools with higher and lower levels of collective efficacy in their perceptions of the image portrayed by using the World Wide Web / Internet in the classroom. Teachers in schools with high and median levels of collective efficacy were found to differ significantly from teachers in schools with lower levels of collective efficacy in the potential status a teacher may obtain within their school from using the World Wide Web / Internet. Additionally this study offers support for Venkatesh and Davis (2000) theoretical proposition that the image construct is less susceptible to the influence of experience an individual may have with a particular computer application. However due to small sample size of this study these results must be interpreted cautiously

Abstract Datatypes in PVS

PVS (Prototype Verification System) is a general-purpose environment for developing specifications and proofs. This document deals primarily with the abstract datatype mechanism in PVS which generates theories containing axioms and definitions for a class of recursive datatypes. The concepts underlying the abstract datatype mechanism are illustrated using ordered binary trees as an example. Binary trees are described by a PVS abstract datatype that is parametric in its value type. The type of ordered binary trees is then presented as a subtype of binary trees where the ordering relation is also taken as a parameter. We define the operations of inserting an element into, and searching for an element in an ordered binary tree; the bulk of the report is devoted to PVS proofs of some useful properties of these operations. These proofs illustrate various approaches to proving properties of abstract datatype operations. They also describe the built-in capabilities of the PVS proof checker for simplifying abstract datatype expressions

Integrated Formal Analysis of Timed-Triggered Ethernet

We present new results related to the verification of the Timed-Triggered Ethernet (TTE) clock synchronization protocol. This work extends previous verification of TTE based on model checking. We identify a suboptimal design choice in a compression function used in clock synchronization, and propose an improvement. We compare the original design and the improved definition using the SAL model checker

“I want to know my bloodline”: New Brunswickers and Their Pasts

New Brunswick is a product of wars fought from 1689 to 1815. During these wars, all of which included battles on North American soil, the social relations among the First Nations, French, and British inhabitants were forged, often in blood. These conflicts became the foundation for mutable but seemingly mutually exclusive identities that are documented in a recent survey of New Brunswickers on how they engage the past in their everyday lives. In this paper, we describe the eighteenth-century context in which many New Brunswick cultural identities were constructed and address the findings of the Canadians and Their Pasts survey in a province where popular engagement with history is complicated by diverse perceptions of the past. Résumé Le Nouveau-Brunswick est le produit de guerres ayant eu lieu entre 1689 et 1815. Pendant ces guerres, qui ont toutes eu des batailles en sol nord-américain, des relations sociales se sont tissées entre les Premières nations, les Français et les Britanniques; souvent, ils étaient unis par les liens du sang. Ces conflits sont à la source d’identités mutables, mais qui étaient, en apparence, mutuellement exclusives et qui ont fait l’objet d’une récente enquête qui portait sur les gens du Nouveau-Brunswick et sur la façon qu’ils évoquent le passé au quotidien. Dans cet exposé, nous décrivons le contexte du 18e siècle dans lequel de nombreuses identités culturelles du Nouveau-Brunswick se sont formées et nous nous penchons sur les résultats du sondage portant sur les Canadiens et leur passé et ce, dans une province où l’engagement populaire envers l’histoire se complique par les diverses perceptions du passé

Process algebra for event-driven runtime verification: a case study of wireless network management

Runtime verification is analysis based on information extracted from a running system. Traditionally this involves reasoning about system states, for example using trace predicates. We have been investigating runtime verification for event-driven systems and in that context we propose a higher level of abstraction can be useful, namely reasoning at the level of user-perceived system events. And when considering events, then the natural formalism for verification is a form of process algebra

A Proof Strategy Language and Proof Script Generation for Isabelle/HOL

We introduce a language, PSL, designed to capture high level proof strategies in Isabelle/HOL. Given a strategy and a proof obligation, PSL's runtime system generates and combines various tactics to explore a large search space with low memory usage. Upon success, PSL generates an efficient proof script, which bypasses a large part of the proof search. We also present PSL's monadic interpreter to show that the underlying idea of PSL is transferable to other ITPs.Comment: This paper has been submitted to CADE2

Machine-Checked Proofs For Realizability Checking Algorithms

Virtual integration techniques focus on building architectural models of systems that can be analyzed early in the design cycle to try to lower cost, reduce risk, and improve quality of complex embedded systems. Given appropriate architectural descriptions, assume/guarantee contracts, and compositional reasoning rules, these techniques can be used to prove important safety properties about the architecture prior to system construction. For these proofs to be meaningful, each leaf-level component contract must be realizable; i.e., it is possible to construct a component such that for any input allowed by the contract assumptions, there is some output value that the component can produce that satisfies the contract guarantees. We have recently proposed (in [1]) a contract-based realizability checking algorithm for assume/guarantee contracts over infinite theories supported by SMT solvers such as linear integer/real arithmetic and uninterpreted functions. In that work, we used an SMT solver and an algorithm similar to k-induction to establish the realizability of a contract, and justified our approach via a hand proof. Given the central importance of realizability to our virtual integration approach, we wanted additional confidence that our approach was sound. This paper describes a complete formalization of the approach in the Coq proof and specification language. During formalization, we found several small mistakes and missing assumptions in our reasoning. Although these did not compromise the correctness of the algorithm used in the checking tools, they point to the value of machine-checked formalization. In addition, we believe this is the first machine-checked formalization for a realizability algorithm.Comment: 14 pages, 1 figur

Career self-efficacy and career decision of African-American, Hispanic, and Anglo students enrolled in selected rural Texas high schools

The study was designed to obtain information that would be of value to secondary school personnel who provide career counseling and guidance to high school students preparing for post-secondary education, training, and employment. The study attempted to determine if African-American, Anglo, and Hispanic students varied significantly on characteristics that could potentially inhibit career decision-making. The characteristics investigated included career indecision and self-efficacy. Participants included 74 sophomore and senior students from three rural high schools in South Central Texas. Two research questions were investigated to determine if there were significant differences among Anglo, African-American, and Hispanic students on measures of career indecision and self-efficacy. A third research question was investigated to determine if significant differences existed on measures of career indecision and self-efficacy by ethnicity, gender, and grade level, as well as for the interaction of ethnicity, gender, and grade level. A supplementary analysis of the three research questions was conducted including school as an independent variable. The Career Decision Scale and Career Decision Self-Efficacy Scale were administered to the participants and the data were analyzed with ANOVA and MANOVA statistical tests. No significant differences were obtained for the three research questions. When the school variable was included in the data analysis, significant main effects differences were found for grade level on self-efficacy and for school on career indecision. The combination of ethnic groups, genders, and grade levels indicated significant differences for the interaction of gender and grade level on self-efficacy and for the interaction of ethnicity and gender on self-efficacy. Middle to high levels of career indecision were reported by 90% of the seniors and 79% of all students in the study. The researcher recommended that career interventions would be valuable to sophomores and seniors in helping them prepare for post-secondary career choices