549 research outputs found
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 âjust outsideâ 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 âplugged-inâ 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 colleaguesâ 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
âI want to know my bloodlineâ: 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-amĂ©ricain, des relations sociales se sont tissĂ©es entre les PremiĂšres nations, les Français et les Britanniques; souvent, ils Ă©taient unis par les liens du sang. Ces conflits sont Ă la source dâidentitĂ©s mutables, mais qui Ă©taient, en apparence, mutuellement exclusives et qui ont fait lâobjet dâune rĂ©cente enquĂȘte qui portait sur les gens du Nouveau-Brunswick et sur la façon quâils Ă©voquent le passĂ© au quotidien. Dans cet exposĂ©, nous dĂ©crivons le contexte du 18e siĂšcle dans lequel de nombreuses identitĂ©s culturelles du Nouveau-Brunswick se sont formĂ©es et nous nous penchons sur les rĂ©sultats du sondage portant sur les Canadiens et leur passĂ© et ce, dans une province oĂč lâengagement populaire envers lâhistoire se complique par les diverses perceptions du passĂ©
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
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
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