J. Scott Carter

  1. A Survey of Quandle Ideas.

    Authors: J. Scott Carter
    Subjects: Geometric Topology
    Abstract

    This article surveys many aspects of the theory of quandles which
    algebraically encode the Reidemeister moves. In addition to knot theory,
    quandles have found applications in other areas which are only mentioned in
    passing here. The main purpose is to give a short introduction to the subject
    and a guide to the applications that have been found thus far for quandle
    cocycle invariants.

  2. Algebraic Structures Derived from Foams.

    Authors: J. Scott Carter, Masahico Saito
    Subjects: Geometric Topology
    Abstract

    Foams are surfaces with branch lines at which three sheets merge. They have
    been used in the categorification of sl(3) quantum knot invariants and also in
    physics. The 2D-TQFT of surfaces, on the other hand, is classified by means of
    commutative Frobenius algebras, where saddle points correspond to
    multiplication and comultiplication. In this paper, we explore algebraic
    operations that branch lines derive under TQFT. In particular, we investigate
    Lie bracket and bialgebra structures.

  3. Symmetric Extensions of Dihedral Quandles and Triple Points of Non-orientable Surfaces.

    Authors: J. Scott Carter, Kanako Oshiro, Masahico Saito
    Subjects: Geometric Topology
    Abstract

    Quandles with involutions that satisfy certain conditions, called good
    involutions, can be used to color non-orientable surface-knots. We use
    subgroups of signed permutation matrices to construct non-trivial good
    involutions on extensions of odd order dihedral quandles.

    For the smallest example of order 6 that is an extension of the three-element
    dihedral quandle, various symmetric quandle homology groups are computed, and
    applications to the minimal triple point number of surface-knots are given.

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