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Alexander polynomials of simple-ribbon knots

Kengo Kishimoto, Tetsuo Shibuya, Tatsuya Tsukamoto, Tsuneo Ishikawa

Abstract

In a previous paper, we introduced special types of fusions, so called simple-ribbon fusions on links. A knot obtained from the trivial knot by a finite sequence of simple-ribbon fusions is called a simple-ribbon knot. Every ribbon knot with <10 crossings is a simple-ribbon knot. In this paper, we give a formula for the Alexander polynomials of simple-ribbon knots. Using the formula, we determine if a knot with 10 crossings is a simple-ribbon knot. Every simple-ribbon fusion can be realized by ``elementary" simple-ribbon fusions. We call a knot a p-simple-ribbon knot if the knot is obtained from the trivial knot by a finite sequence of elementary p-simple-ribbon fusions for a fixed positive integer p. We provide a condition for a simple-ribbon knot to be both of an m-simple-ribbon knot and an n-simple-ribbon knot for positive integers m and n.

Alexander polynomials of simple-ribbon knots

Abstract

In a previous paper, we introduced special types of fusions, so called simple-ribbon fusions on links. A knot obtained from the trivial knot by a finite sequence of simple-ribbon fusions is called a simple-ribbon knot. Every ribbon knot with <10 crossings is a simple-ribbon knot. In this paper, we give a formula for the Alexander polynomials of simple-ribbon knots. Using the formula, we determine if a knot with 10 crossings is a simple-ribbon knot. Every simple-ribbon fusion can be realized by ``elementary" simple-ribbon fusions. We call a knot a p-simple-ribbon knot if the knot is obtained from the trivial knot by a finite sequence of elementary p-simple-ribbon fusions for a fixed positive integer p. We provide a condition for a simple-ribbon knot to be both of an m-simple-ribbon knot and an n-simple-ribbon knot for positive integers m and n.

Paper Structure

This paper contains 3 sections, 12 theorems, 14 equations, 10 figures, 1 table.

Key Result

Theorem 1.1

Let $K$ be a knot obtained from a knot $k$ by an elementary $m$-SR-fusion with an attendant knot $\beta$ and with $p$ positive bands. Let $l=\mathrm{lk}(\beta, k)$ and $\varphi(t\,;m,p,l)=(1-t)^m - t^{\,l} (-t)^p$. Then we have the following.

Figures (10)

  • Figure 1: ribbon knots with less than or equal to nine crossings
  • Figure 2:
  • Figure 3:
  • Figure 4:
  • Figure 5:
  • ...and 5 more figures

Theorems & Definitions (21)

  • Theorem 1.1
  • Corollary 1.2
  • Lemma 1.3
  • proof
  • Proposition 1.4
  • proof
  • Theorem 1.5
  • Theorem 1.6
  • Proposition 2.1
  • proof
  • ...and 11 more