Now showing items 1-20 of 32

    • Almost affine codes and matroids 

      Diachkov, Konstantin (Master thesis; Mastergradsoppgave, 2017-05-15)
      In this thesis we study various types of block codes, like linear, mutlti-linear, almost affine codes. We also look at how these codes can be described by associated matroids. In addition we look at flags (chains) of codes and see how their behavior can be described using demi-matroids. We also introduce weight polynomials for almost affine codes.
    • Almost complex homogeneous spaces with semi-simple isotropy 

      Winther, Henrik (Master thesis; Mastergradsoppgave, 2012-05)
      We classify the almost complex structures on homogeneous spaces M = G/H of real dimension less than or equal to 6 with semi-simple isotropy group H.
    • Arctic tipping points 

      Smolkova, Valentina (Master thesis; Mastergradsoppgave, 2015-05-15)
      The Arctic is warming much faster than the entire planet, and this causes severe melting of sea ice. However, the climate of different regions of the Earth is interconnected, and changes in the amount of ice in the Arctic can dramatically affect the climate across the whole planet. Some scientists claim that a possible tipping point is the event of the ice-free Arctic Ocean in summer. Certain ...
    • A complex contour based perfectly matched layer applied to a pattern generating model equation. 

      Jenssen, Amund (Master thesis; Mastergradsoppgave, 2017-02-17)
      The observable universe consists of several non equilibrium systems that generate spatiotemporal behaviour in the form of various patterns. As the elementary laws of physics and chemistry are unable to explain the pattern forming behaviour of such systems, scientists have turned to desktop experiments and model equations to gain further insight. The model equations that generate numerical solutions ...
    • Deforming the vacuum. On the physical origin and numerical calculation of the Casimir effect. 

      Mikalsen, Karl Øyvind (Master thesis; Mastergradsoppgave, 2014-05-14)
      A new method for calculating the Casimir force between compact objects was introduced in May 2012 by Per Jakobsen and Isak Kilen. In this method a regularization procedure is used to reduce the pressure to the solution of an integral equation defined on the boundaries of the objects. In this thesis the method is further developed by extending from a 2D to a 3D massless scalar field, subject to ...
    • Differential invariants of the 2D conformal Lie algebra action 

      Høyem, Marte Rørvik (Master thesis; Mastergradsoppgave, 2008-02-15)
      In this thises we consider the Lie algebra that corresponds to the Lie pseudogroup of all conformal transformations on the plane. This conformal Lie algebra is canonically represented as a Lie algebra of vector fields on R^2. We will find all possible representations of vector fields in R^3=J^0R^2 which projects to the canonical representation and find the algebra of scalar differential invariants ...
    • Distributing a private key generator in Ad hoc Networks 

      Stenberg, Eystein Måløy (Master thesis; Mastergradsoppgave, 2009-05-15)
      A Mobile Ad hoc Network (MANET) is a wireless network that does not rely on a fixed infrastructure. These characteristics make algorithms that route network traffic particularly vulnerable to attack. Mechanisms used to protect against such attacks often depend on cryptographic keys. Since the nodes in a MANET have limited resources, designing methods for cryptographic key management is ...
    • Extensions of groups and modules 

      Nermo, Catalina Nicole Vintilescu (Master thesis; Mastergradsoppgave, 2010)
      The main goal of this thesis is to build up detailed constructions and give complete proofs for the extension functors of modules and groups, which we define using cohomology functors. Further, we look at the relations that appear between these and short exact sequences of modules, respectively groups. We calculate also several concrete cohomology groups, and build extensions that are described by ...
    • The Four Faces of Hyperelliptic curves 

      Boyne, Marcus L. (Master thesis; Mastergradsoppgave, 2020-05-13)
      In this thesis we will look at elliptic and hyperelliptic curves. There are three abelian groups that are isomorphic to hyperelliptic curves. The Jacobian of hyperelliptic curves, the ideal class group and the form class group, will all be defined and given abelian group structure. We will give an algorithm for point addition and point doubling done exclusively in the jacobian of the curve. ...
    • Group Cohomology and Extensions 

      Breivik, Markus Nordvoll (Master thesis; Mastergradsoppgave, 2019-08-31)
      The goal of this thesis is to classify all extensions where the kernel has order p^s and the cokernel has order p^t, p is a prime, and 1 ≤ s,t ≤ 2. We determine (up to weak congruence) the different combinations of kernel, cokernel and operators, and for each case, calculate the second cohomology group. By comparing resolutions, we get an explicit correspondence between the second cohomology group ...
    • High frequency financial time series prediction: machine learning approach 

      Zankova, Ekaterina (Master thesis; Mastergradsoppgave, 2016-05-13)
      Machine learning is a rapidly evolving subfield of computer science. It has enormous amount of applications. One of the application domains is financial data analysis. Machine learning was usually applied for analysis and forecasting of daily financial time series. Availability of high frequency financial data became another challenge with its own specifics and difficulties. Regressors, being a ...
    • Homological methods applied to theory of codes and matroids 

      Karpova, Anna (Master thesis; Mastergradsoppgave, 2015-05-15)
      In this thesis we first give a survey of linear error-correcting codes, and how many of their most important properties only depend on the matroids derived from their parity check matrices. We also introduce the Stanley-Reisner ring associated to the simplicial complex of the independent sets of a matroid. We then recall in particular how some important properties of linear codes, including their ...
    • Hopf algebras and monoidal categories 

      Bakke, Tørris Koløen (Master thesis; Mastergradsoppgave, 2007-06-14)
      In this thesis we study the correspondence between categorical notions and bialgebra notions, and make a kind of dictionary and grammar book for translation between these notions. We will show how to obtain an antipode, and how to define braidings and quantizations. The construction is done in two ways. First we use the properties of a bialgebra to define a monoidal structure on (co)modules over ...
    • Insulating the Vacuum. Calculating the Casimir force using the boundary integral method with von Neumann boundary conditions 

      Utheim, Marius (Master thesis; Mastergradsoppgave, 2016-08-15)
      In 2012, a new method for calculating the Casimir force between compact objects was developed, expressing the force in terms of a boundary integral equation. The case of perfectly conducting objects with Dirichlet boundary conditions in two dimensions was treated by Isak Kilen. The method was later extended to three dimensions by Karl Øyvind Mikalsen. The contribution of this thesis will be to ...
    • Kompleksiteten til noen kryptologisk viktige algoritmer 

      Brattli, Tore (Master thesis; Mastergradsoppgave, 1990-04-04)
      Denne hovedfagsoppgaven har som mål å sammenligne teoretisk og praktisk kompleksitet til algoritmer som har stor kryptologisk betydning. Et av målene er å avsløre den skjulte konstanten bak O-notasjonen, slik at algoritmene kan sammenlignes på et reelt grunnlag. I tillegg er det sett på sammenheng mellom sikkerhet, størrelsen på tall, asymptotisk og praktisk kompleksitet. Spesielt algoritmer som ...
    • Light induced forces on dielectric nanospheres 

      Lundamo, Trine (Master thesis; Mastergradsoppgave, 2008-02-15)
      Waves that are reflected and refracted by material bodies also transfer momentum to these bodies. This means that the wave field induces a force on the bodies, and multiple reflections between bodies induce forces between them. Light is an electromagnetic wave phenomenon, and the waves carry energy and momentum. Hence, any object that is scattering and refracting light is also acted upon by a ...
    • Local classification of 2-dimensional solvable Lie algebra actions on the plane. 

      Gustad, Christian O'cadiz (Master thesis; Mastergradsoppgave, 2010-05)
      In the thesis the local classification of 2-dimensional solvable Lie algebra action on the plane is given. Normal forms of such actions are found. The classification applied to classifcation of 2nd order differential equations that are solvable in quadratures.
    • Mathematics of Viral Infections: A Review of Modeling Approaches and A Case-Study for Dengue Dynamics 

      Yong, Chung Han (Master thesis; Mastergradsoppgave, 2018-09-20)
      In this thesis we use mathematical models to study the mechanisms by which diseases spread. Transmission dynamics is modelled by the class of SIR models, where the abbreviation stands for susceptible (S), infected (I) and recovered (R). These models are also called compartmental models, and they serve as the basic mathematical framework for understanding the complex dynamics of infectious diseases. ...
    • Matroids, demi-matroids and chains of linear codes 

      Martin, James Aloysius (Master thesis; Mastergradsoppgave, 2010-12-09)
      The central theme of this thesis is the study of matroids and related concepts such as linear codes and graphs. Demi-matroids, structures which arise from a relaxation of the definition of a matroid are explored along with related themes. Finally we examine the fact that some results in coding theory are essentially consequences of results for demi-matroids.
    • Modelling high intensity laser pulse propagation in air using the modified Korteweg-de Vries equation 

      Rørnes, Bjarne (Master thesis; Mastergradsoppgave, 2018-06-01)
      Ultrafast laser pulse experiments and applications are entering a phase that challenges the validity of mathematical models utilised to model longer pulses in nonlinear optics. This thesis aims to propose a possible mathematical model for high intensity laser pulse propagation in air through a multiple scales expansion of Maxwell’s equations and discuss a method on how to solve the corresponding ...