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  • 1.
    Allen, M. R.
    et al.
    Department of Pure Mathematics, University of Waterloo, Waterloo, Ontario, Canada.
    Cruttwell, G. S. H.
    Department of Mathematics and Statistics, Dalhousie University, Halifax, N.S., Canada.
    Hare, Kathryn E.
    Department of Pure Mathematics, University of Waterloo, Waterloo, Ontario, Canada.
    Rönning, Jan-Olav
    University of Skövde, School of Life Sciences.
    Dimensions of fractals in the large2007In: Chaos, Solitons & Fractals, ISSN 0960-0779, E-ISSN 1873-2887, Vol. 31, no 1, p. 5-13Article in journal (Refereed)
  • 2.
    Amouzgar, Kaveh
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Product Development Department, School of Engineering, Jönköping University, Jönköping, Sweden.
    Strömberg, Niclas
    Department of Mechanical Engineering, School of Science and Technology, University of Örebro, Sweden.
    Radial basis functions as surrogate models with a priori bias in comparison with a posteriori bias2017In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 55, no 4, p. 1453-1469Article in journal (Refereed)
    Abstract [en]

    In order to obtain a robust performance, the established approach when using radial basis function networks (RBF) as metamodels is to add a posteriori bias which is defined by extra orthogonality constraints. We mean that this is not needed, instead the bias can simply be set a priori by using the normal equation, i.e. the bias becomes the corresponding regression model. In this paper we demonstrate that the performance of our suggested approach with a priori bias is in general as good as, or even for many test examples better than, the performance of RBF with a posteriori bias. Using our approach, it is clear that the global response is modelled with the bias and that the details are captured with radial basis functions. The accuracy of the two approaches are investigated by using multiple test functions with different degrees of dimensionality. Furthermore, several modeling criteria, such as the type of radial basis functions used in the RBFs, dimension of the test functions, sampling techniques and size of samples, are considered to study their affect on the performance of the approaches. The power of RBF with a priori bias for surrogate based design optimization is also demonstrated by solving an established engineering benchmark of a welded beam and another benchmark for different sampling sets generated by successive screening, random, Latin hypercube and Hammersley sampling, respectively. The results obtained by evaluation of the performance metrics, the modeling criteria and the presented optimal solutions, demonstrate promising potentials of our RBF with a priori bias, in addition to the simplicity and straight-forward use of the approach.

  • 3.
    Bennet, Christian
    et al.
    Göteborgs universitet.
    Sjögren, Jörgen
    University of Skövde, School of Life Sciences.
    Philosophy and mathematics education2013In: Modus Tolland: En festskrift med anledning av Anders Tollands sextioårsdag / [ed] Filip Radovic & Susanna Radovic, Göteborg: Göteborgs universitet , 2013, p. 9-23Chapter in book (Other (popular science, discussion, etc.))
  • 4.
    Bennet, Christian
    et al.
    Göteborgs universitet.
    Sjögren, Jörgen
    University of Skövde, School of Life Sciences. University of Skövde, Health and Education.
    The Viability of Social Constructivism as a Philosophy of Mathematics2013In: Croatian Journal of Philosophy, ISSN 1333-1108, E-ISSN 1847-6139, Vol. XIII, no 39, p. 341-355Article in journal (Refereed)
    Abstract [en]

    Attempts have been made to analyse features in mathematics within a social constructivist context. In this paper we critically examine some of those attempts recently made with focus on problems of the objectivity, ontology, necessity, and atemporality of mathematics. Our conclusion is that these attempts fare no better than traditional alternatives, and that they, furthermore, create new problems of their own.

  • 5.
    Billing, Erik
    et al.
    Umeå universitet, Institutionen för datavetenskap.
    Servin, Martin
    Institutionen för fysik, Umeå universitet.
    Composer: A prototype multilingual model composition tool2013In: MODPROD2013: 7th MODPROD Workshop on Model-Based Product Development / [ed] Peter Fritzson, Umeå: Umeå universitet , 2013Conference paper (Other academic)
    Abstract [en]

    Facing the task to design, simulate or optimize a complex system itis common to find models and data for the system expressed in differentformats, implemented in different simulation software tools. When a newmodel is developed, a target platform is chosen and existing componentsimplemented with different tools have to be converted. This results inunnecessary work duplication and lead times. The Modelica languageinitiative [2] partially solves this by allowing developers to move modelsbetween different tools following the Modelica standard. Another possi-bility is to exchange models using the Functional Mockup Interface (FMI)standard that allows computer models to be used as components in othersimulations, possibly implemented using other programming languages[1]. With the Modelica and FMI standards entering development, there isneed for an easy-to-use tool that supports design, editing and simulationof such multilingual systems, as well as for retracting system informationfor formulating and solving optimization problems.A prototype solution for a graphical block diagram tool for design, edit-ing, simulation and optimization of multilingual systems has been createdand evaluated for a specific system. The tool is named Composer [3].The block diagram representation should be generic, independent ofmodel implementations, have a standardized format and yet support effi-cient handling of complex data. It is natural to look for solutions amongmodern web technologies, specifically HTML5. The format for represent-ing two dimensional vector graphics in HTML5 is Scalable Vector Graphics(SVG). We combine the SVG format with the FMI standard. In a firststage, we take the XML-based model description of FMI as a form for de-scribing the interface for each component, in a language independent way.Simulation parameters can also be expressed on this form, and integratedas metadata into the SVG image. 

    The prototype, using SVG in conjunction with FMI, is implementedin JavaScript and allow creation and modification of block diagrams directly in the web browser. Generated SVG images are sent to the serverwhere they are translated to program code, allowing the simulation ofthe dynamical system to be executed using selected implementations. Analternative mode is to generate optimization problem from the systemdefinition and model parameters. The simulation/optimization result is 

    returned to the web browser where it is plotted or processed using otherstandard libraries.The fiber production process at SCA Packaging Obbola [4] is used asan example system and modeled using Composer. The system consists oftwo fiber production lines that produce fiber going to a storage tank [5].The paper machine is taking fiber from the tank as needed for production.A lot of power is required during fiber production and the purpose of themodel was to investigate weather electricity costs could be reduced byrescheduling fiber production over the day, in accordance with the electricity spot price. Components are implemented for dynamical simulationusing OpenModelica and for discrete event using Python. The Python implementation supports constraint propagation between components andoptimization over specified variables. Each component is interfaced as aFunctional Mock-up Unit (FMU), allowing components to be connectedand properties specified in language independent way. From the SVGcontaining the high-level system information, both Modelica and Pythoncode is generated and executed on the web server, potentially hosted ina high performance data center. More implementations could be addedwithout modifying the SVG system description.We have shown that it is possible to separate system descriptions onthe block diagram level from implementations and interface between thetwo levels using FMI. In a continuation of this project, we aim to integratethe FMI standard also for co-simulation, such that components implemented in different languages could be used together. One open questionis to what extent FMUs of the same component, but implemented withdifferent tools, will have the same model description. For the SVG-basedsystem description to be useful, the FMI model description must remainthe same, or at least contain a large overlap, for a single component implemented in different languages. This will be further investigated in futurework.

  • 6.
    Chokhachian, Ata
    et al.
    The Technical University of Munich, Germany.
    Hooshyar Yousefi, Bahram
    The Vienna University of Technology, Austria.
    Toward Object-Oriented Knowledge-Based Parametric Design Thinking2015Conference paper (Refereed)
    Abstract [en]

    The parameter, as a variable of differentiation, defines the limits and boundaries of a system and the conditions for its operation. It is through parameters that we are able to produce certain logical relationships between different parts in design procedure. Fundamental to this, however, is the assumption that the object or phenomenawe are modeling is in fact quantifiable. Advances in computational processing have promoted our capacity, and thus faith in the ability, to systematically classify and itemize the world around us. The Parametricism Manifesto concerns itself solely with appearance and arejection of the term Parametricism in certain levels could be clearly visible within the contemporary discourse of Object-oriented and knowledge-based approach that reflects the cognitive attitude of the designer/architect regarding the object-oriented reasoning and analogy. Moreover, instead of having parametric manifestation alternate terms such as digitally intelligent design , algorithmic design, object oriented design , Context-oriented design , Parametric thinking , and even postparametric design have arisen and could be used to describe this vastly differentiated field. What these design theories do share, however, is a predilection and belief in the tool. Nowadays the project fields are information-rich contexts and the tool sets for design are able to interpret, analyze, synthesize and realize these data into the design procedure. This research mainly aims to uncover potentialities of the existing enablers and assistive technologies in context-oriented design in order to have more content-embedded architectural conceptualization solutions.

  • 7.
    Griggs, Terry
    et al.
    The Open University, UK.
    Stokes, Klara
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    On Pentagonal Geometries with Block Size 3, 4 or 52016In: Symmetries in Graphs, Maps, and Polytopes: 5th SIGMAP Workshop, West Malvern, UK, July 2014 / [ed] Jozef Širáň, Robert Jajcay, Springer, 2016, p. 147-157Chapter in book (Refereed)
  • 8.
    Gundeboina, Saidulu
    University of Skövde, School of Technology and Society.
    Finite Element Analysis of a Washing Machine Cylinder2010Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis a finite element model of a household washing machine cylinder is built and analysed in ABAQUS 6.9-2. The aim is to help Asko appliances in conducting similar analysis for future manufacturing of high capacity cylinders by reducing experimentation. The analysis is mainly concerned with an evenly distributed load at a constant angular velocity. The load is applied with the help of lead plates instead of clothes. The cylinder is loaded with three thin (2 mm) lead plates weighing 2 kg each. The plates with dimensional 370x240x2 mm are mounted with one strip of double sided foam tape inside the cylinder. To estimate the behavior of the cylinder the strains are measured when the cylinder is rotating at 1620 and 2200 revolution per minute (rpm). To validate the model the numerical analyses are compared with experimental results. The results clearly show that the numerical strain values fit with experimental strain values.

  • 9.
    Hare, Kathryn E.
    et al.
    Department of Pure Mathematics, University of Waterloo, Waterloo, Ontario, Canada.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    Applications of generalized Perron trees to maximal functions and density bases1998In: Journal of Fourier Analysis and Applications, ISSN 1069-5869, E-ISSN 1531-5851, Vol. 4, no 2, p. 215-227Article in journal (Refereed)
  • 10.
    Hare, Kathryn E.
    et al.
    Department of Pure Mathematics, University of Waterloo, Canada.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    Fractal dimensions of infinite product spaces2004In: International journal of pure and applied mathematics, ISSN 1311-8080, E-ISSN 1314-3395, Vol. 14, no 2, p. 139-167Article in journal (Refereed)
  • 11.
    Hare, Kathryn E.
    et al.
    Department of Pure Mathematics, University of Waterloo, Waterloo, Ontario Canada.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    The size of Max(p) sets and density bases2002In: Journal of Fourier Analysis and Applications, ISSN 1069-5869, E-ISSN 1531-5851, Vol. 8, no 3, p. 259-268Article in journal (Refereed)
  • 12.
    Höglund, Marlen
    University of Skövde, School of Humanities and Informatics.
    När kan jag använda mina kunskaper i matematik?: teoretisk och praktisk betydelse för grundskolans matematik2011Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I skolan anses matematiken vara ett viktigt ämne och den upptar en stor del av skolans undervisningstid. Däremot har det märkts en trend bland eleverna i grundskolan att de mer och mer ifrågasätter varför de över huvud taget måste lära sig matematik. Ren matematik som de läser i skolan kan det många gånger vara svårt att se nyttan med. Påföljande matematik blir då sedan svårare och svårare att ge bra motiveringar till varför man bör kunna.  Många elever och vuxna känner även en ren ångest när man pratar om ämnet matematik. Vad är egentligen matematik, var används den och till vad? Var kommer matematiken ifrån? Hur uppstod den? Är det intressant och relevant för elever att få kunskap om detta? Har matematikundervisningen följt den snabba samhällsutvecklingen och vad behöver vi egentligen lära oss för matematik i grundskolan? Behöver alla få undervisning i matematik? Matematiken finns överallt omkring oss och synen på matematiken eleverna erhållit har formats av hela samhället. Hur mycket påverkar läraren elevernas inställning och vad har föräldrarna för del i det hela? Studien tar upp det matematiska lärandet, matematikens användande och den matematiska fostran.

  • 13.
    Izquierdo, Milagros
    et al.
    Department of Mathematics, Linköping University, Linköping, Sweden.
    Stokes, Klara
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Isometric point-circle configurations on surfaces from uniform maps2016In: Symmetries in Graphs, Maps, and Polytopes: 5th SIGMAP Workshop, West Malvern, UK, July 2014 / [ed] Jozef Širáň, Robert Jajcay, Springer, 2016, p. 201-212Chapter in book (Refereed)
    Abstract [en]

    We embed neighborhood geometries of graphs on surfaces as point-circle configurations. We give examples coming from regular maps on surfaces with a maximum number of automorphisms for their genus, and survey geometric realization of pentagonal geometries coming from Moore graphs. An infinite family of point-circle v4 configurations on p-gonal surfaces with two p-gonal morphisms is given. The image of these configurations on the sphere under the two p-gonal morphisms is also described.

  • 14.
    Järkehed, Jennie
    et al.
    University of Skövde, School of Humanities and Informatics.
    Mellgren, Hanna
    University of Skövde, School of Humanities and Informatics.
    Från utopi till generell princip: Lärares uppfattningar av individanpassad undervisning i matematik2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    According to the Swedish curriculum of 1994 one of the teacher’s assignments is to individualize the teaching. In published official reports, newspaper articles and thesis it appears that students mathematic knowledge is decreasing. Reasons for this could possibly be that focus in the individualized teaching of mathematics turns more towards private schoolwork. According to our experience of individualized teaching in mathematics this statement agrees relatively well. We think that in some cases teachers have a hard time to comply with every student’s conditions and needs. A lack that we think can explain why the students don’t reach the goals in the ninth grade, which are described in the syllabus of mathematics, is despite the fact that the teachers have an assignment to individualize the teaching doesn’t have enough knowledge of the conception to do it. The purpose of this essay is to make researches into teacher’s different conceptions of individualized teaching of mathematics in the early years of school. Through a qualitative methodology with interview as a technique and with a starting point in fenomenografin, was the overarching purpose to contribute with knowledge within the field of education in mathematics. The idea was to contribute to the debate about the necessity of strengthening the student’s knowledge of mathematics. The purpose was also to discuss with implications that could be the consequence of the teacher’s interpretations. The result of the study shows that there are four quality distinct categories of teacher’s conceptions of individualized teaching in mathematics. The conceptions of individualized teaching in mathematics as a general principle of teaching, individualized teaching in mathematics as something that is positive yet impracticable, individualized teaching in mathematics as a method and individualized teaching of mathematics from different students. This study has shown that individualized teaching in mathematic makes the teaching more democratic, the student gets a better presumption to learn the basics of mathematics and that the student gets an increased self-confidence regarding mathematics.

  • 15.
    Karlsson, Stefan
    Göteborgs universitet.
    Topics on cubic hypersurfaces1998Doctoral thesis, monograph (Other academic)
  • 16.
    Lowe, Robert
    University of Hertfordshire.
    The Evolution of Affective Displays and Related Strategies2007Doctoral thesis, monograph (Other academic)
  • 17.
    Lowe, Robert
    et al.
    Adaptive Systems Research Group, School of Computer Science, University of Hertfordshire.
    Cañamero, Lola
    Adaptive Systems Research Group, School of Computer Science, University of Hertfordshire.
    Nehaniv, Chrystopher L.
    Adaptive Systems Research Group, School of Computer Science, University of Hertfordshire.
    Polani, Daniel
    Adaptive Systems Research Group, School of Computer Science, University of Hertfordshire.
    The Evolution of Affect-Related Displays, Recognition and Related Strategies2004In: Artificial Life IX: Proceedings of the Ninth International Conference on the Simulation and Synthesis of Living Systems / [ed] Jordan Pollack, Mark Bedau, Phil Husbands, Takashi Ikegami, & Richard A. Watson, MIT Press, 2004, p. 176-181Conference paper (Refereed)
  • 18.
    Lowe, Robert
    et al.
    Adaptive Systems Research Group, Faculty of Engineering and Information Sciences, University of Hertfordshire.
    Cañamero, Lola
    Adaptive Systems Research Group, Faculty of Engineering and Information Sciences, University of Hertfordshire.
    Nehaniv, Chrystopher
    Adaptive Systems Research Group, Faculty of Engineering and Information Sciences, University of Hertfordshire.
    Polani, Daniel
    Adaptive Systems Research Group, Faculty of Engineering and Information Sciences, University of Hertfordshire.
    Strategies in the Evolution of Affect Related Displays and Recognition2004In: The Logic of Artificial Life: Abstracting And Synthesizing The Principles Of Living Systems: Proceedings of the 6th German Workshop on Artificial Life, April 14-16, 2004, Bamberg, Germany, IOS Press, 2004, p. 89-95Conference paper (Refereed)
  • 19.
    Lowe, Robert
    et al.
    Adaptive Systems Research Group, Faculty of Engineering and Information Sciences, University of Hertfordshire, United Kingdom.
    Polani, Daniel
    Adaptive Systems Research Group, Faculty of Engineering and Information Sciences, University of Hertfordshire, United Kingdom.
    Preventing bluff agent invasions in honest societies2003In: Advances in Artificial Life: 7th European Conference, ECAL 2003, Dortmund, Germany, September 14-17, 2003. Proceedings / [ed] Wolfgang Banzhaf, Jens Ziegler, Thomas Christaller, Peter Dittrich, Jan T. Kim, Springer Berlin/Heidelberg, 2003, p. 118-127Conference paper (Refereed)
  • 20.
    Mellin, Jonas
    University of Skövde, The Informatics Research Centre. University of Skövde, School of Informatics.
    The effect of optimizing engine control on fuel consumption and roll amplitude in ocean-going vessels: An experimental study2015Report (Other academic)
    Abstract [en]

    We use data-generated models based on data from experiments of an ocean-going vessel to study the effect of optimizing fuel consumption. The optimization is an add-on module to the existing diesel-engine fuel-injection control built by Q-TAGG R&D AB. The work is mainly a validation of knowledge-based models based on a priori knowledge from physics. The results from a simulation-based analysis of the predictive models built on data agree with the results based on knowledge-based models in a companion study. This indicates that the optimization algorithm saves fuel. We also address specific problems of adapting data to existing machine learning methods. It turns out that we can simplify the problem by ignoring the auto-correlative effects in the time series by employing low-pass filters and resampling techniques. Thereby we can use mature and robust classification techniques with less requirements on the data to demonstrate that fuel is saved compared to the full-fledged time series analysis techniques which are harder to use. The trade-off is the accuracy of the result, that is, it is hard to tell exactly how much fuel is saved. In essence, however, this process can be automated due to its simplicity. 

  • 21.
    Pettersson, Kerstin
    University of Skövde, School of Life Sciences.
    Samspel mellan intuitiva idéer och formella bevis: en fallstudie av universitetsstudenters arbete med en analysuppgift2004Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    The aim of this study is to illuminate the interplay between intuitive ideas and formal justification. In a perspective where we focus on the students’ competences we describe the interaction between intuitive ideas and formal structures, as they appear especially in relation to concept definitions and formal proofs. A group of university students have been working on a task in calculus. The task includes the concepts function and derivative and requires of them to use a proof by induction. The discussion between the members of the group has been analyzed in accordance with the principles of intentional analysis, a method by which we regard the students’ activities as intentional. This method of analysis makes the process of interpretation visible. It also makes it possible to make explicit the competences of the students’ and the mathematical content of their actions. In the study examples are given of the interplay between the intuitive ideas and the formal structures and also of the function for this interplay. The students have rich concept images and access to intuitive ideas relevant to the concepts brought to the 4 fore by the task. During the group discussion all components of a complete proof are included in the students’ reasoning. The students create a proof by induction which matches the ordinary pattern for such a proof, but they do not themselves regard it as a proof fitting into the ordinary scheme of argumentation, as they remember it from text-books and teaching. The students put heavy demands upon the formalization of their ideas and these demands are sometimes hampering the problem solving process, but they also encourage the students to expand their search for a solution to the problem at hand.

  • 22.
    Pettersson, Kerstin
    University of Skövde, School of Life Sciences.
    Växelverkan mellan intuitiva idéer och formella resonemang: En fallstudie av universitetsstudenters arbete med en analysuppgift2008In: Nordisk matematikkdidaktikk, ISSN 1104-2176, Vol. 13, no 1, p. 29-50Article in journal (Refereed)
    Abstract [sv]

    Studiens syfte är att visa hur en växelverkan mellan intuitiva idéer och formella resonemang kan gestalta sig i en problemlösningsprocess. Studien visar att universitetsstudenter redan under sitt första år av matematikstudier förmår utnyttja en sådan växelverkan. En grupp studenter har arbetat med en analysuppgift som berör begreppen funktion och derivata samt inkluderar ett induktionsbevis. Studenterna utnyttjar i den kreativa processen intuitiva idéer och formella resonemang i ett dynamiskt samspel. Växlingarna har ett flertal funktioner: att kontrollera intuitiva uppfattningar, att skaffa nya utgångspunkter för problemlösningsprocessen, att ekonomisera resonemang och att driva arbetet vidare.

  • 23.
    Pettersson, Kerstin
    et al.
    University of Skövde, School of Life Sciences.
    Scheja, Max
    Algorithmic contexts and learning potentiality: A case study of students' understanding of calculusManuscript (Other academic)
  • 24.
    Runesson, Ulla
    University of Skövde, School of Humanities and Informatics.
    A collective enquiry into critical aspects of teaching the concept of angles2007In: Nordisk matematikkdidaktikk, ISSN 1104-2176, Vol. 12, no 4, p. 7-25Article in journal (Refereed)
    Abstract [en]

    This paper describes an approach to teaching that enhances pupils’ learning in mathematics. The model described – Learning study – involves teachers and researchers cooperating in an iterative process, gathering data about teaching and pupils’ learning, analysing the data, planning and revising their teaching. A particular theoretical framework was used as a guiding principle when designing and analysing learning. The goal was to identify aspects critical for learning the angle concept. It is demonstrated how the teachers were able to identify the critical aspects and change the teaching in a way that promoted pupils’ learning. What these critical aspects may entail and what teachers and researchers can learn from a Learning study is discussed.

  • 25.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    A convergence result for square roots of the Poisson kernel in the bidisk1999In: Mathematica Scandinavica, ISSN 0025-5521, E-ISSN 1903-1807, Vol. 84, no 1, p. 81-92Article in journal (Refereed)
  • 26.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    Convergence results for the square root of the Poisson kernel1997In: Mathematica Scandinavica, ISSN 0025-5521, E-ISSN 1903-1807, Vol. 81, no 2, p. 219-235Article in journal (Refereed)
  • 27.
    Rönning, Jan-Olav
    University of Skövde, School of Engineering Science.
    On convergence for the square root of the Poisson kernel in symmetric spaces of rank 11997In: Studia Mathematica, ISSN 0039-3223, E-ISSN 1730-6337, Vol. 125, no 3, p. 219-229Article in journal (Refereed)
  • 28.
    Rönning, Jan-Olav
    et al.
    University of Skövde, Department of Natural Sciences.
    Svensson, Olof
    Linköpings Universitet, Campus Norrköping, Institutionen för teknik och naturvetenskap.
    Convergence for the square root of the Poisson kernel in rank one symmetric spaces against boundary functions with regularity: Preprint Chalmers och Göteborgs Universitet, (79)2001Manuscript (preprint) (Other academic)
  • 29.
    Scheja, Max
    et al.
    Stockholm Univ, Dept Educ, S-10691 Stockholm, Sweden.
    Pettersson, Kerstin
    University of Skövde, School of Life Sciences.
    Transformation and contextualisation: exploring students' conceptual understandings od threshold concept in calculus2010In: Higher Education, ISSN 0018-1560, E-ISSN 1573-174X, Vol. 59, no 2, p. 221-241Article in journal (Refereed)
  • 30.
    Sjögren, Jörgen
    University of Skövde, School of Life Sciences. Dept. of Philosophy, Linguistics, and Theory of Science, University of Göteborg.
    A Note on the Relation Between Formal and Informal Proof2010In: Acta Analytica, ISSN 0353-5150, E-ISSN 1874-6349, Vol. 25, no 4, p. 447-458Article in journal (Refereed)
    Abstract [en]

    Using Carnap’s concept explication, we propose a theory of concept formation in mathematics. This theory is then applied to the problem of how to understand the relation between the concepts formal proof (deduction) and informal, mathematical proof.

  • 31.
    Sjögren, Jörgen
    University of Skövde, School of Life Sciences. Department of Philosophy, Linquistics, Theory of Science, University of Gothenburg, Sweden.
    Holism and Indispensability2012In: Logique et Analyse, ISSN 0024-5836, E-ISSN 2295-5836, Vol. 55, no 219, p. 463-476Article in journal (Refereed)
    Abstract [en]

    One questioned premiss in the indispensability argument of Quine and Putnam is confirmational holism. In this paper I argue for a weakened form of holism, and thus a strengthened version of the indispensability argument. The argument is based on an idea of concept formation in mathematics. Mathematical concepts are arrived at via a sequence of explications, in Carnap's sense, of non-clear, originally empirical, concepts. I identify a deductive and an empirical component in mathematical concepts. In a test situation the use of the empirical component, but not of the deductive one, is corroborated or falsified together with the scientific theory.

  • 32.
    Sjögren, Jörgen
    University of Skövde, School of Life Sciences.
    Measuring the Power of Arithmetical Theories2005Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    This thesis discusses the possibility to measure the power of extentions of Peano Aritmetic, P A. It consists of three parts, an introduction and two separately written papers. In the introduction we present the problem and briefly give an account of van Lambalgen's and raatikainen's criticism of gnenralization of two versions of Chaitin's incompleteness theorem, and reinforces the above mentioned criticism. The second paper is the main paper of the thesis, and here, using the modal logic GL, we design a measure of the power, in terms of the capacity to prove theorems, of an important set of extentions of P A.

  • 33.
    Sjögren, Jörgen
    University of Skövde, School of Life Sciences. Department of Philosophy/Logic, University of Göteborg, Gothenburg, Sweden.
    On explicating the concept the power of an arithmetical theory2008In: Journal of Philosophical Logic, ISSN 0022-3611, E-ISSN 1573-0433, Vol. 37, no 2, p. 183-202Article in journal (Refereed)
    Abstract [en]

    In this paper I discuss possible ways of measuring the power of arithmetical theories, and the possiblity of making an explication in Carnap’s sense of this concept. Chaitin formulates several suggestions how to construct measures, and these suggestions are reviewed together with some new and old critical arguments. I also briefly review a measure I have designed together with some shortcomings of this measure. The conclusion of the paper is that it is not possible to formulate an explication of the concept.

  • 34.
    Sjögren, Jörgen
    University of Skövde, School of Engineering Science. University of Skövde, Health and Education.
    Philosophy of Mathematics and Mathematics Education: Some Reflections2014In: IDÉES FIXES: A festschrift dedicated to Christian Bennet on the occasion of his 60th birthday / [ed] Martin Kaså, Göteborg: Department of Philosophy, Linguistics and Theory of Science , 2014, p. 85-100Chapter in book (Refereed)
  • 35.
    Sjögren, Jörgen
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, Health and Education.
    Bennet, Christian
    Department of Pedagogical, Curricular and Professional Studies, University of Gothenburg, Sweden.
    Concept Formation and Concept Grounding2014In: Philosophia (Ramat Gan), ISSN 0048-3893, E-ISSN 1574-9274, Vol. 42, no 3, p. 827-839Article in journal (Refereed)
    Abstract [en]

    Recently Carrie S. Jenkins formulated an epistemology of mathematics, or rather arithmetic, respecting apriorism, empiricism, and realism. Central is an idea of concept grounding. The adequacy of this idea has been questioned e.g. concerning the grounding of the mathematically central concept of set (or class), and of composite concepts. In this paper we present a view of concept formation in mathematics, based on ideas from Carnap, leading to modifications of Jenkins’s epistemology that may solve some problematic issues with her ideas. But we also present some further problems with her view, concerning the role of proof for mathematical knowledge.

  • 36.
    Stokes, Klara
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Irreducibility of configurations2016In: Ars Mathematica Contemporanea, ISSN 1855-3966, Vol. 10, no 1, p. 169-181Article in journal (Refereed)
  • 37.
    Stokes, Klara
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Patterns of ideals of numerical semigroups2016In: Semigroup Forum, ISSN 0037-1912, E-ISSN 1432-2137, Vol. 93, no 1, p. 180-200Article in journal (Refereed)
  • 38.
    Stokes, Klara
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Izquierdo, Milagros
    Department of Mathematics, Linköping University, Linköping Sweden.
    Geometric point-circle pentagonal geometries from Moore graphs2016In: Ars Mathematica Contemporanea, ISSN 1855-3966, Vol. 11, no 1, p. 215-229Article in journal (Refereed)
  • 39.
    Stokes, Klara
    et al.
    Universitat Rovira i Virgili, Tarragona, Spain.
    Torra, Vicenç
    Universitat Autònoma de Barcelona (UAB), Spain.
    On some clustering approaches for graphs2011In: Fuzzy Systems (FUZZ), 2011, IEEE conference proceedings, 2011, p. 409-415Conference paper (Refereed)
    Abstract [en]

    In this paper we discuss some tools for graph perturbation with applications to data privacy. We present and analyse two different approaches. One is based on matrix decomposition and the other on graph partitioning. We discuss these methods and show that they belong to two traditions in data protection: noise addition/microaggregation and k-anonymity.

  • 40.
    Stokes, Klara
    et al.
    Universitat Rovira i Virgili, Tarragona, Spain.
    Torra, Vicenç
    Universitat Autònoma de Barcelona (UAB), Spain.
    On the Relationship Between Clustering and Coding Theory2012In: 2012 IEEE International Conference on Fuzzy Systems: Brisbane, Australia (June 10-15, 2012) / [ed] Hussein Abbass, Daryl Essam & Ruhul Sarker, IEEE conference proceedings, 2012, p. Article number 6250783-Conference paper (Refereed)
    Abstract [en]

    In this paper we discuss the relations between clustering and error correcting codes. We show that clustering can be used for constructing error correcting codes. We review the previous works found in the literature about this issue, and propose a modification of a previous work that can be used for code construction from a set of proposed codewords.

  • 41.
    Stokes, Klara
    et al.
    Universitat Rovira i Virgili, Tarragona, Catalonia, Spain.
    Torra, Vicenç
    IIIA, Institut d’Investigació en Intel ligència Artificial CSIC, Consejo Superior de Investigaciones Científicas, Bellaterra, Catalonia, Spain.
    Reidentification and k-anonymity: a model for disclosure risk in graphs2012In: Soft Computing - A Fusion of Foundations, Methodologies and Applications, ISSN 1432-7643, E-ISSN 1433-7479, Vol. 16, no 10, p. 1657-1670Article in journal (Refereed)
    Abstract [en]

    In this article we provide a formal framework for reidentification in general. We define n-confusion as a concept for modeling the anonymity of a database table and we prove that n-confusion is a generalization of k-anonymity. After a short survey on the different available definitions of k-anonymity for graphs we provide a new definition for k-anonymous graph, which we consider to be the correct definition. We provide a description of the k-anonymous graphs, both for the regular and the non-regular case. We also introduce the more flexible concept of (k, l)-anonymous graph. Our definition of (k, l)-anonymous graph is meant to replace a previous definition of (k, l)-anonymous graph, which we here prove to have severe weaknesses. Finally, we provide a set of algorithms for k-anonymization of graphs.

  • 42.
    Tadesse, Yohannes
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Using Edge-induced and Vertex-induced Subhypergraph Polynomials2015In: Mathematica Scandinavica, ISSN 0025-5521, E-ISSN 1903-1807, Vol. 117, no 2, p. 161-169Article in journal (Refereed)
    Abstract [en]

    For a hypergraph H, we consider the edge-induced and vertex-induced subhypergraph polynomials and study their relation. We use this relation to prove that both polynomials are reconstructible, and to prove a theorem relating the Hilbert series of the Stanley-Reisner ring of the independent complex of H and the edge-induced subhypergraph polynomial. We also consider reconstruction of some algebraic invariants of H.

  • 43.
    Torra, Vicenç
    et al.
    Institut d'Investigacío en Intellig̀encia Artificial, Consejo Superior de Investigaciones Cient́ficas, Universitat Aut̀onoma de Barcelona, Bellaterra, Catalonia, Spain.
    Stokes, Klara
    Departments of Computer Science and Mathematics, Universitat Rovira i Virgili, Tarragona, Spain / UNESCO Chair in Data Privacy, Tarragona, Catalonia, Spain.
    Narukawa, Yasuo
    Toho Gakuen, Tokyo, Japan / Department of Computational Intelligence and Systems Science, Tokyo Institute of Technology, Yokohama, Japan.
    An extension of fuzzy measures to multisets and its relation to distorted probabilities2012In: IEEE transactions on fuzzy systems, ISSN 1063-6706, E-ISSN 1941-0034, Vol. 20, no 6, p. 1032-1045Article in journal (Refereed)
    Abstract [en]

    Fuzzy measures are monotonic set functions on a reference set; they generalize probabilities replacing the additivity condition by monotonicity. The typical application of these measures is with fuzzy integrals. Fuzzy integrals integrate a function with respect to a fuzzy measure, and they can be used to aggregate information from a set of sources (opinions from experts or criteria in a multicriteria decision-making problem). In this context, background knowledge on the sources is represented by means of the fuzzy measures. For example, interactions between criteria are represented by means of nonadditive measures. In this paper, we introduce fuzzy measures on multisets. We propose a general definition, and we then introduce a family of fuzzy measures for multisets which we show to be equivalent to distorted probabilities when the multisets are restricted to proper sets

  • 44.
    Åkerblad, Niklas
    University of Skövde, School of Humanities and Informatics.
    Animationsarbete till spelet Colosseum: Code of Hammurabi: en studie i hur man skapar animationer till ett spel utifrån dess kontext och spelsystem utan att kunna testa dessa i en prototyp.2007Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport behandlar det animationsarbete som jag gått igenom för att försöka skapa så trovärdiga och dynamiska animationer som möjligt till spelet Colosseum: Code of Hammurabi och dess nya omarbetade stridssystem. Jag har utgått från ett relativt sparsmakat designdokument som i princip bara förklarar kortfattat hur spelmekaniken ska fungera på en grundläggande nivå samt en animationslista på animationer som ska finnas i spelet. Spelet ska i slutändan innehålla 3 olika vapenstilar men på grund av tidsbrist har jag valt att fokusera på en av dess, nämligen kampstilen för strid med tvåhandssvärd. Först har jag analyserat det gamla stridssystemet för att ha en grund att stå på, för att bland annat se vilka brister mitt tidigare arbete präglats av. Utifrån diverse referenser som behandlar medeltida stridkonst inom nyss nämnda kampstil har jag hämtat det mesta av inspirationen och följaktligen kryddat dessa jordnära anvisningar med mina egna idéer samt ett antal fightingspel med spektakulära kontexter och även försökt dra nytta av det material som finns i kampsportsfilmer. Mycket av arbetet har cirkulerat kring att lära sig hur animationer implementeras i ett stridssystem och vilka tekniska samt programmerarmässiga relationer man måste ta hänsyn till. Jag har även försökt ha Disneys 12 animationsprinciper i bakhuvudet för att ha en teoretisk källa till hur animation ska se ut och fungera.

1 - 44 of 44
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