A linear translation from CTL* to the first-order modal μ -calculus

The modal μ-calculus is a very expressive temporal logic. In particular, logics such as LTL, CTL and CTL* can be translated into the modal μ-calculus, although existing translations of LTL and CTL* are at least exponential in size. We show that an existing simple first-order extension of the modal μ-calculus allows for a linear translation from LTL. Furthermore, we show that solving the translated formulae is as efficient as the best known methods to solve LTL formulae directly.     

Network State Estimation and Prediction for Real-Time Traffic Management

Advanced Traveler Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) have the potential to contribute to the solution of the traffic congestion problem. DynaMIT is a real-time system that can be used to generate guidance for travelers. The main principle on which DynaMIT is based is that information should be consistent, and user optimal. Consistency implies that the traffic conditions experienced by the travelers are consistent with the condition assumed in generating the guidance. To generate consistent user optimal information, DynaMIT performs two main functions: state estimation and prediction. A demand simulator and a supply simulator interact to perform these tasks. A case study demonstrates the value of the system.     

The role of algorithm and result comprehensibility of automated scheduling on complacency

Several studies have stressed that even expert operators who are aware of a machine's limits could adopt its proposals without questioning them (i.e., the complacency phenomenon). In production scheduling for manufacturing, this is a significant problem, as it is often suggested that the machine be allowed to build the production schedule, confining the human role to that of rescheduling. This article evaluates the characteristics of scheduling algorithms on human rescheduling performance, the quality of which was related to complacency. It is suggested that scheduling algorithms be characterized as having result comprehensibility (the result respects the scheduler's expectations in terms of the discourse rules of the information display) or algorithm comprehensibility (the complexity of the algorithm hides some important constraints). The findings stress, on the one hand, that result comprehensibility is necessary to achieve good production performance and to limit complacency. On the other hand, algorithm comprehensibility leads to poor performance due to the very high cost of understanding the algorithm. © 2008 Wiley Periodicals, Inc.     

A multi-level, multi-theory perspective of information technology implementation

Abstract.  Much of information technology (IT) implementation research has focused on individuals' acceptance of IT by examining their behaviour when faced with new IT and the antecedents of these behaviours. As they are frequently undertaken within a project framework, IT implementations also entail the application of project management practices in order to be successful. Based on the premise that antecedents of lower level theories are frequently determined by the outcomes of a higher level theory, the present paper illustrates how organizational-level decisions, examined from the perspective of economics theories, can help explain the antecedents of project risk management at the project and individual levels. To do so, the paper describes an IT implementation effort which went through three phases; the first two of which were abandoned versions of the same project. An organizational-level analysis of the case from an economics perspective and its project-level analysis from a risk management perspective show how organizational-level decisions influenced the antecedents at the project and individual levels, providing a more complete understanding of the IT implementation in question, an understanding which neither a theory approach nor a level perspective could provide on its own.     

Occupational health problems and injuries among Quebec's physical educators

The purpose of this study was to describe the traumatology of teaching physical education (PE) and to document the causes and mechanisms of injuries in this occupation. Our sample was composed of 314 physical educators (PEs) teaching at three school levels (primary school, secondary school and college) who responded to a questionnaire survey. The results showed a 0.55 rate of recent lesion per teacher per year (0.65 for women and 0.51 for men). A total of 37.6% of subjects were affected by a lesion during the last year at work. Subjects with a higher weekly frequency of leisure physical activities or endurance activities (five times and more) were less affected by chronic lesions as well as those who frequently practiced aerobic physical activities. Prevalence of chronic injuries was higher in older teachers. Our results confirm that the rate of lesions in this group of workers is high, and that school level and respondent age may influence the rate of lesion and the characteristics of risk factors. In particular, the effect of ageing and teaching specialization on the incidence of occupational problems in PEs warrants further research. Given the relatively high rate of injuries among PE teachers, we suggest that it is necessary to further explore preventive strategies to reduce occupational risk in these workers. In particular, prophylactic physical activity outside of work may represent such a strategy since PEs more active outside their work have lower chronic injury prevalence. PEs gave long periods of standing the highest rating for movements or positions most likely to cause them occupational injuries. It can thus be suggested to find ways to reduce standing position sustained for long periods.     

Property Testing of Regular Tree Languages

We consider the edit distance with moves on the class of words and the class of ordered trees. We first exhibit a simple tester for the class of regular languages on words and generalize it to the class of ranked and unranked regular trees. We also show that this distance problem is -complete on ordered trees. A preliminary version of this paper appeared in Proceedings of 31st International Colloquium on Automata, Languages and Programming, volume 3142 of Lecture Notes in Computer Science, pages 932–944, Springer, 2005. Work supported by ACI Sécurité Informatique: VERA of the French Ministry of research.     

Extension of the decidability of the marked PCP to instances with unique blocks

In the Post Correspondence Problem (PCP) an instance (h,g)$(h,g)$ consists of two morphisms h$h$ and g$g$, and the problem is to determine whether or not there exists a nonempty word w$w$ such that h(w)=g(w)$h\left(w\right)=g\left(w\right)$. Here we prove that the PCP is decidable for instances with unique blocks using the decidability of the marked PCP. Also, we show that it is decidable whether an instance satisfying the uniqueness condition for continuations has an infinite solution. These results establish a new and larger class of decidable instances of the PCP, including the class of marked instances.     

Listener-based analysis of surface importance for acoustic metrics

Acoustic quality in room acoustics is measured by well defined quantities, like definition, which can be derived from simulated impulse response filters or measured values. These take into account the intensity and phase shift of multiple reflections due to a wave front emanating from a sound source. Definition (D50) and clarity (C50) for example correspond to the fraction of the energy received in total to the energy received in the first 50 ms at a certain listener position. Unfortunately, the impulse response measured at a single point does not provide any information about the direction of reflections, and about the reflection surfaces which contribute to this measure. For the visualization of room acoustics, however, this information is very useful since it allows to discover regions with high contribution and provides insight into the influence of all reflecting surfaces to the quality measure. We use the phonon tracing method to calculate the contribution of the reflection surfaces to the impulse response for different listener positions. This data is used to compute importance values for the geometry taking a certain acoustic metric into account. To get a visual insight into the directional aspect, we map the importance to the reflecting surfaces of the geometry. This visualization indicates which parts of the surfaces need to be changed to enhance the chosen acoustic quality measure.We apply our method to the acoustic improvement of a lecture hall by means of enhancing the overall speech comprehensibility (clarity) and evaluate the results using glyphs to visualize the clarity (C50) values at listener positions throughout the room.     

Software assessment using metrics: A comparison across large C++ and Java systems

This paper presents an assessment method to evaluate the quality of object oriented software systems. The assessment method is based on source code abstraction, object–oriented metrics and graphical representation. The metrics used and the underlying model representing the software are presented. The assessment method experiment is part of an industrial research effort with the Bell Canada Quality Engineering and Research Group. It helps evaluators assess the quality and risks associated with software by identifying code fragments presenting unusual characteristics. The assessment method evaluates object–oriented software systems at three levels of granularity: system level, class level and method level. One large C++ and eight Java software systems, for a total of over one million lines of code, are presented as case studies. A critical analysis of the results is presented comparing the systems and the two languages.