Viser treff 41-48 av 48

    • 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.
    • 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 ...
    • 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 ...
    • 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 ...
    • 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 ...
    • 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 ...
    • The use of elliptic curves in cryptography 

      Juhas, Tibor (Master thesis; Mastergradsoppgave, 2007-06)
      The use of elliptic curves in cryptography was suggested independently by Neal Koblitz and Victor Miller in 1985. Being a relatively new field, there is still a lot of ongoing research on the subject, but elliptic curve cryptography, or ECC for short, has already been implemented in real-life applications. Its strength was proved in 2003 when the U.S. National Security Agency adopted ECC for protecting ...
    • 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 ...