Sökning: "ring lemma"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden ring lemma.

  1. 1. On the ring lemma

    Författare :Jonatan Vasilis; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ring lemma; circle packing; sphere packing; Apollonian; sphere packing;

    Sammanfattning : The sharp ring lemma states that if n ≥ 3 cyclically tangent discs with pairwise disjoint interiors are externally tangent to and surround the unit disc, then no disc has a radius below cn = (F2n-1 + F2n-2 - 1)-1 – where Fk denotes the kth Fibonacci number – and that the lower bound is attained in essentially unique Apollonian configurations. Here we give a proof by transforming the problem to a class of strip configurations, after which we closely follow a method of proof due to Aharonov and Stephenson. LÄS MER

  3. 2. The Diamond Lemma for Power Series Algebras

    Författare :Lars Hellström; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematical analysis; diamond lemma; power series algebra; Gröbner basis; embedding into skew fields; archimedean element in semigroup; q-deformed Heisenberg--Weyl algebra; polynomial degree; ring norm; Birkhoff orthogonality; filtered structure; Matematisk analys; Mathematical analysis; Analys; Mathematics; matematik;

    Sammanfattning : The main result in this thesis is the generalisation of Bergman's diamond lemma for ring theory to power series rings. This generalisation makes it possible to treat problems in which there arise infinite descending chains. LÄS MER

  4. 3. On the Picard Group of Integer Group Rings

    Författare :Ola Helenius; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Picard group; Grothendieck group; integer group ring; cyclic group; cyclotomic field; class group; Kummer´s lemma; semi-regular prime; Picard group;

    Sammanfattning : .... LÄS MER

  5. 4. Intersections on moduli spaces of curves

    Författare :Sergei Shadrin; Torsten Ekedahl; Carel Faber; Stockholms universitet; []
    Nyckelord :Mathematics;

    Sammanfattning : We present a new approach to perform calculations with the certain standard classes in cohomology of the moduli spaces of curves. It is based on an important lemma of Ionel relating the intersection theoriy of the moduli space of curves and that of the space of admissible coverings. LÄS MER

  7. 5. On Amoebas and Multidimensional Residues

    Författare :Johannes Lundqvist; Mats Andersson; Martín Sombra; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; amoeba; multidimensional residue; duality principle; effective; uniform; Artin-Rees; Ronkin function; Mathematics; matematik;

    Sammanfattning : This thesis consists of four papers and an introduction. In Paper I we calculate the second order derivatives of the Ronkin function of an affine polynomial in three variables. This gives an expression for the real Monge-Ampére measure associated to the hyperplane amoeba. LÄS MER