1,721,013 research outputs found
Symmetry-preserving operations on maps
No full textAl duizenden jaren worden symmetrie-bewarende operaties zoals het duaal nemen of truncatie toegepast op polyeders, maar tot enkele jaren geleden was er geen methode om al deze operaties op dezelfde algemene manier te beschrijven. Dit veranderde in 2017 met de definitie van 'local (orientation-preserving) symmetry-preserving operations', afgekort als l(op)sp-operaties. In dit doctoraat wordt deze definitie gebruikt om heel algemene stellingen te bewijzen over al deze operaties. Zo moet niet elke operatie apart bekeken worden, maar kunnen de algemene stellingen gebruikt worden om resultaten over specifieke operaties te bekomen. Meer specifiek wordt er in dit doctoraat gekeken naar het effect van lsp- en lopsp-operaties op de samenhang en het minimum genus van ingebedde grafen. Er wordt ook onderzocht wanneer zulke operaties de symmetrie van een ingebedde graaf kunnen verhogen. Naast theoretisch werk heeft deze thesis ook een meer praktische component. Als deel van het doctoraat werd een programma ontwikkeld dat op een efficiënte manier lopsp-operaties kan genereren. Dit kan bijvoorbeeld gebruikt worden om nieuwe stellingen of vermoedens te testen
Physical computing in primary and secondary education : techniques and tools for teaching and assessment
No full textComputer science is becoming an increasingly important part of primary and secondary education. This change is backed by a societal shift towards a digital economy. The European Commis- sion wants 100% of key public services to be online and 90% of small- and medium-sized businesses to reach at least a basic level of digital intensity. It is clear that the integration of computer science in education is important in order to reach these goals. Nevertheless, this is not a trivial task. There are many unknowns about how to do this effectively, moreover, these unknowns are distributed across multiple areas of policy and practice. In this dissertation, we identify some of these unknowns and formulate some possible solutions. We mainly focus on supporting teach- ing practice but also formulate insights which can be helpful for making policy decisions.
Since the field of computing education is very broad, we focus on the integration of programming in a physical computing context for learners ages 10 to 14. To conduct research in this field, we first created a visual programming environment for physical systems. This environment is based on existing literature and is used as a tool throughout this work. It allows learners to build and program robots both in the real world and in simulation. This strong link between the physical and virtual word allows the environment to be used in many different learning contexts, allowing us to conduct a variety of in classroom experiments.
Using the environment we created, we have shown that not all ways of integrating programming into a physical computing class are equally effective. Specifically, our results show that having learners create a program from scratch is preferable to having them find errors in existing programs. Our metrics indicate that finding errors in an existing program has more risk of causing ex- traneous cognitive load in learners. Cognitive load theory states that the human mind has a limited working memory. In order for effective learning to take place, the capacity of the working memory should not be exceeded. Even though fixing a program only required learners to change one element in the code, the act of understanding what the code does, applying error detection strategies, and deducing what they can do to fix the issue, causes more cognitive load than constructing a fully functional program from scratch. As a result, learners in the fix group get stuck more often, lose motivation more quickly, tend to use trial-and-error solution strategies more often, and score lower on programming tests.
Since effective teaching not only depends on the teaching method but also on the teacher, we have developed methods for support- ing teachers in their efforts to integrate programming into their teaching. To identify the most pressing needs teachers have, we set up a qualitative experiment during one of the professional de- velopment programs we created. By observing and interviewing teachers, we identified two main challenges teachers encounter. 1) The ability and willingness to create, reuse and share edu- cational materials. 2) How to assess the coding ability of their learners especially in an open learning context.
We aimed to address these issues by designing and developing different tools and techniques for supporting teachers. Our ef- forts include the design and implementation of a learning object repository, a tool for sharing learning content on the web, as well as a framework for the assessment of code. The learning object repository defines a unified way of creating and sharing educational content. It solves the issues of granularity, heterogene- ity, reuse, personalization, and sharing. We argue that having a uniform system for defining learning content is important to facilitate personalized learning.
The assessment framework we developed can be used by teach- ers to get insight into the aspects of code that can be assessed, giving them a grip on how to give quality feedback. It focusses on feedback of visual programs to learners ages 12 to 14. The teachers for these age groups need the most support since they usually have to teach multiple subjects and are less of an expert in each of the topics they teach. To develop this framework, we identified the gap between the existing literature about the assessment of code and how teachers perform the assessment in practice. Consequently, its strength is the link between theory and practice. The framework consists of eight main categories: 1) functionality 2) readability 3) programming concepts 4) algo- rithmic thinking 5) testing and debugging 6) mathematical con- cepts 7) creativity 8) personal aspects. Each of these categories is then split up into concepts relevant in the context of visual programming. Comparing this framework to what teachers as- sess in practice has shown that teachers are mostly unaware of these categories. This often results in incomplete, inaccurate, or invalid feedback. Additionally, the range of concepts being considered by teachers seems to grow with teaching experience. Nevertheless, even more experienced teachers are often not fully aware of which exact concepts they are assessing.
Finally, we describe a method to assist teachers with their assess- ment of code by visualizing the solution paths of learners. This requires techniques to extract educationally relevant informa- tion from code. Consequently, we developed different machine learning based techniques for extracting didactical information from code and for visualizing solution paths in our programming environment. Our system extracts structural and functional in- formation from programs and embeds it into a vector space. The structural information is extracted using a Gaussian vertex edge histogram kernel. This kernel defines the structural similarity between two abstract syntax trees which can be used to cluster similar programs together. To extract functional information, we executed the programs in a simulated environment and captured the internal program state at each time step. By transforming these state variations in time into both frequency and amplitude components, we are able to create a vector representing the func- tion of a program. These vectors can be used as input for several machine learning algorithms. This allows us to cluster similar programs together and create visualizations based on the similarity of solution paths. This proof of concept application lays the groundwork for automated feedback systems
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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