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Investigating Optimal Progress Measures for Verification of the WebSocket Protocol
Get PDFThe sweep-line method is a state space reduction technique formemory-efficient on-the-fly verification of concurrent systems. Themethod relies on a progress measure capturing inherent progress in thesystem under verification to store only fragments of the state space inmemory at a time and thereby reduce peak memory usage. The sweep-line method has been applied to many concurrent systems, but theoptimality of progress measures in terms of the peak number of statesstored has not been investigated. Assessing the optimality of a progressmeasure is important since memory in most cases is the limiting factorin verification using state spaces. We derive lower bounds for the peaknumber states and present initial experimental results on near optimalprogress measures for verification of the IETF WebSocket protocol
How teachers reflect on textbook materials and how they utilise them
Get PDFThis paper provides an overview of research findings and information in the area of teachers’ use of textbook materials. Furthermore, it presents the results of qualitative research dedicated to this issue, which was carried out with three Czech primary school teachers. These results were acquired on the basis of direct lesson observations as well as analysis of video recordings and interviews. The results show what innovative textbook materials can bring to teachers, who is open to thinking about subject matter and its didactic transformations, and what they can bring to those who are less open or less willing to dedicate their time and attention to this reflection. The results also offer some findings regarding what textbook materials should look like if these groups of teachers are to work with them effectively. The selected teachers see themselves as the ones who decide on instructional content although they base their decisions on textbook materials. Interpretation of the methodology suggested in textbook materials and their subsequent utilisation depends largely on the teaching approach adopted by individual teachers. All teachers agreed that textbook materials should be concise and should contain inspirational methodology ideas. Not all of them wanted to use textbooks as a source of their own learning
Latency Thresholds for Usability in Games: A Survey
Get PDFUser interactions in interactive applications are time critical operations;late response will degrade the experience. Sensitivity to delay doeshowever vary greatly with between games. This paper surveys existingliterature on the specifics of this limitation. We find a classificationwhere games are grouped with others of roughly the same requirements.In addition we find some numbers on how long latency is acceptable.These numbers are however inconsistent between studies, indicatinginconsistent methodology or insufficient classification of games andinteractions. To improve classification, we suggest some changes.In general, research is too sparse to draw any strong or statisticallysignificant conclusions. In some of the most time critical games, latencyseems to degrade the experience at about 50 ms
Deadlock detection of active objects with synchronous and asynchronous method calls
Get PDFOpen distributed systems are essential in today’s softwaresolutions. However, not all programming paradigms providenatural support for such systems. The setting of concurrentobjects is attractive since it supports independent units ofcomputation. In particular we consider concurrent objectscommunicating by asynchronous method calls supporting non-blocking as well as blocking method calls. In this settingwaiting time can be reduced, allowing efficient cooperationbetween objects. With this concurrency model, deadlock isavoided if blocking calls are avoided. However, blocking callsare sometimes needed to control the order of computation. Thenon-hierarchical nature of concurrent objects systems gives riseto non-trivial deadlock situations. Deadlocks may occur if thereis a call chain with at least one blocking call.We propose amethod for static detection of deadlocks, and demonstrate itsuse on a non-trivial example
Visual Query Formulation for Linked Open Data: The Norwegian Entity Registry Case
Get PDFThe cloud of Linked Open Data is steadily growing, yet it remains largelyinaccessible to the general public, due to the technical barrier posed bythe requirement to know a formal query language such as SPARQL. Inthis article, we present a new approach for visual query formulation towardarbitrary SPARQL endpoints, and we show a working prototype developedto improve the accessibility to Linked Open Data sources for non-computerexperts. We show how the prototype can be employed to simplify access togovernmental Linked Open Data with a case study from the Norwegian EntityRegistry
A Genetic Approach to Tuning Compact Trie Clustering
Get PDFThe Compact Trie method for document clustering is sensitive to the kind oftext it is applied to, but contains various parameters that may be tuned foradaptation to specific applications. We implement a genetic algorithm foroptimizing these parameters and apply it to a corpus of texts to demonstratethe feasibility of using genetic algorithms for tuning
Building sentiment Lexicons applying graph theory on information from three Norwegian thesauruses
Get PDFSentiment lexicons are the most used tool to automatically predict sentimentin text. To the best of our knowledge, there exist no openly availablesentiment lexicons for the Norwegian language. Thus in this paper weapplied two different strategies to automatically generate sentiment lexiconsfor the Norwegian language. The first strategy used machine translation totranslate an English sentiment lexicon to Norwegian and the other strategyused information from three different thesauruses to build several sentimentlexicons. The lexicons based on thesauruses were built using the Labelpropagation algorithm from graph theory. The lexicons were evaluatedby classifying product and movie reviews. The results show satisfyingclassification performances. Different sentiment lexicons perform well onproduct and on movie reviews. Overall the lexicon based on machinetranslation performed the best, showing that linguistic resources in Englishcan be translated to Norwegian without losing significant value
Predicting Teachers’ Choice of Teaching and Learning Materials: A Survey Study with Swedish Teachers
Get PDFFew Swedish studies have investigated how teachers choose teaching and learning materials. In the context of choosing teaching and learning materials Sweden provides a particularly interesting case because the country undergone a transformation from high state regulation to a self-regulated market. Consequently, the overall aim of this article is to investigate how teachers choose teaching and learning materials. The following research questions were the focus: How do teachers choose teaching and learning materials? What predicts teachers’ choice of teaching and learning materials? In the current study, 319 teachers filled out a questionnaire regarding their choice of teaching and learning materials. The descriptive statistics indicate that the content matters most to teachers when choosing teaching and learning materials. Readability is in the middle and commercials are at the bottom. The non-recursive structure of the model demonstrated that professional experience decreases teachers’ preferences for content. Talking to colleagues about teaching and learning materials increases teachers’ preferences for adhering to collegial recommendations. Special educators are more concerned with content and readability than ordinary teachers. However, special educators are also less prone to be guided by past experiences when selecting teaching and learning materials
Readability of PTA Textbooks and Reading Comprehension Rates of PTA Students
Get PDFThe purpose of this study was to determine if correlations exist between independent reading comprehension levels of students measured by the Nelson Denny Reading Test (NDRT), readability of textbooks used for instruction and the National Physical Therapy Exam (NPTE) in a Physical Therapist Assistant (PTA) Program.Applications of NDRT, readability formulas, and textbooks were identified.NDRT, course, and NPTE scores of 161 graduates of the PTA program were used. Multiple readability formulas were applied to five textbooks. Correlations were calculated.Mean NDRT- total score was 14.67. Three of five textbooks had higher readability levels than the mean NDRT reading comprehension levels of students. A moderate positive correlation existed between NDRT and NPTE scores
Australian classroom teacher homework practices in designing homework learning resources
Get PDFThere has been considerable research into the design and development of teaching and learning resources for classroom instruction. However, far less research emphasis exists concerning the design and development of learning resources for homework and out-of-school learning. In Australia the approach tends to be a classroom-up approach to the design, development and implementation of learning resources. In this approach, the classroom teachers’ role is of critical importance in designing, developing and implementing learning resources that support homework. In this respect, Horsley and Walker (2012) have found that a relationship exists between classroom teachers’ homework practices and the teaching and learning resource base of these practices.This paper presents preliminary results from a research investigation concern-ing the approach taken by two primary classroom teachers in the design, development and use of homework teaching and learning resources. The research explored teacher perspectives on homework practices using focus groups, and examined actual teacher homework practices using a stimulated recall method