Asynchronous Announcements

We propose a multi-agent epistemic logic of asynchronous announcements, where truthful announcements are publicly sent but individually received by agents, and in the order in which they were sent. Additional to epistemic modalities the logic contains dynamic modalities for making announcements and for receiving them. What an agent believes is a function of her initial uncertainty and of the announcements she has received. Beliefs need not be truthful, because announcements already made may not yet have been received. As announcements are true when sent, certain message sequences can be ruled out, just like inconsistent cuts in distributed computing. We provide a complete axiomatization for this \emph{asynchronous announcement logic} (AA). It is a reduction system that also demonstrates that any formula in $AA$ is equivalent to one without dynamic modalities, just as for public announcement logic. The model checking complexity is in PSPACE. A detailed example modelling message exchanging processes in distributed computing in $AA$ closes our investigation

Power saving in wireless ad hoc networks without synchronization

Power saving strategies generally attempt to maximize the time that nodes spend in a low power consumption sleep state. Such strategies often require the sender to notify the receiver about pending traffic using some form of traffic announcement. Although asynchronous traffic announcement mechanisms are particularly suitable for the ad hoc environment, they also provide relatively limited power savings. This paper proposes a mechanism that improves the efficiency of asynchronous traffic announcement mechanisms by reducing the proportion of time that nodes need to spend awake, while still maintaining good connectivity properties. The mechanism is based on allowing traffic announcements to be rebroadcast by neighbouring nodes

Encoding CSP into CCS

We study encodings from CSP into asynchronous CCS with name passing and matching, so in fact, the asynchronous pi-calculus. By doing so, we discuss two different ways to map the multi-way synchronisation mechanism of CSP into the two-way synchronisation mechanism of CCS. Both encodings satisfy the criteria of Gorla except for compositionality, as both use an additional top-level context. Following the work of Parrow and Sj\"odin, the first encoding uses a centralised coordinator and establishes a variant of weak bisimilarity between source terms and their translations. The second encoding is decentralised, and thus more efficient, but ensures only a form of coupled similarity between source terms and their translations.Comment: In Proceedings EXPRESS/SOS 2015, arXiv:1508.0634

Cognitive and Social Help Giving in Online Teaching: An Exploratory Study

While literature suggests that college students may be less reluctant to seek help in online rather than traditional courses, little is known about how online instructors give help in ways that lead to increased student help seeking and academic success. In this study, we used theories and research on learning assistance and scaffolding, teacher immediacy, social presence, and academic help seeking to explore through a cross-case study design how three online instructors differed in their use of cognitive and social supports and how those differences related to student perceptions of support, help seeking, and performance. Primary data sources included all course postings by the instructors, interviews with the instructors, observational field notes on course discussions, student interviews, and final student grades. Archived course documents and student discussion postings were secondary data sources. Data analysis revealed that while all instructors provided cognitive and social support, they varied in their level of questioning, use of direct instruction, support for task structuring, and attention to group dynamics. This variation in teaching presence related to differences across the courses in student perceptions of support, student help seeking in course discussions, and final course grades. Implications for online teaching and suggestions for further research are offered

e-Sem: Dynamic Seminar Management System for Primary, Secondary and Tertiary Education

This paper describes the dynamic seminar management system named 'e-Sem', developed according to the opensource software philosophy. Due to its dynamic management functionality, it can equally adapt to any education environment (Primary, Secondary, Tertiary). The purpose of the proposed dynamic system is ease of use and handling, by any class of users, without the need of special guidance. Also, students are given the opportunity to: a) register as users; b) enroll in seminars in a simple way; c) receive e-learning material at any time of day any day of week, and d) be informed of new announcements concerning the seminar in which they are enrolled . In addition, the administrator and the tutors have a number of tools such as : management seminars and trainees in a friendly way, sending educational material as well as new announcements to the trainees; the possibility of electronic recording of presence or absence of the trainees in a seminar, and direct printing of a certificate of successful attendance of a seminar for each trainee. The application also offers features such as electronic organization, storage and presentation of educational material, overcoming the limiting factors of space and time of classical teaching, thus creating a dynamic environmen

A Score-Driven Conditional Correlation Model for Noisy and Asynchronous Data: an Application to High-Frequency Covariance Dynamics

The analysis of the intraday dynamics of correlations among high-frequency returns is challenging due to the presence of asynchronous trading and market microstructure noise. Both effects may lead to significant data reduction and may severely underestimate correlations if traditional methods for low-frequency data are employed. We propose to model intraday log-prices through a multivariate local-level model with score-driven covariance matrices and to treat asynchronicity as a missing value problem. The main advantages of this approach are: (i) all available data are used when filtering correlations, (ii) market microstructure noise is taken into account, (iii) estimation is performed through standard maximum likelihood methods. Our empirical analysis, performed on 1-second NYSE data, shows that opening hours are dominated by idiosyncratic risk and that a market factor progressively emerges in the second part of the day. The method can be used as a nowcasting tool for high-frequency data, allowing to study the real-time response of covariances to macro-news announcements and to build intraday portfolios with very short optimization horizons.Comment: 30 pages, 10 figures, 7 table

Maximising Social Interactions and Effectiveness within Distance Learning Courses: Cases from Construction

Advanced Internet technologies have revolutionised the delivery of distance learning education. As a result, the physical proximity between learners and the learning providers has become less important. However, whilst the pervasiveness of these technological developments has reached unprecedented levels, critics argue that the student learning experience is still not as effective as conventional face-to-face delivery. In this regard, surveys of distance learning courses reveal that there is often a lack of social interaction attributed to this method of delivery, which tends to leave learners feeling isolated due to a lack of engagement, direction, guidance and support by the tutor. This paper defines and conceptualises this phenomenon by investigating the extent to which distance-learning programmes provide the social interactions of an equivalent traditional classroom setting. In this respect, two distance learning case studies were investigated, covering the UK and Slovenian markets respectively. Research findings identified that delivery success is strongly dependent on the particular context to which the specific distance learning course is designed, structured and augmented. It is therefore recommended that designers of distance learning courses should balance the tensions and nuances associated with commercial viability and pedagogic effectiveness