Strong and weak (1, 2, 3) homotopies on knot projections

Noboru Ito, Yusuke Takimura

研究成果: Article査読

2 被引用数 (Scopus)

抄録

A knot projection is an image of a generic immersion from a circle into a two-dimensional sphere. We can find homotopies between any two knot projections by local replacements of knot projections of three types, called Reidemeister moves. This paper defines an equivalence relation for knot projections called weak (1, 2, 3) homotopy, which consists of Reidemeister moves of type 1, weak type 2, and weak type 3. This paper defines the first nontrivial invariant under weak (1, 2, 3) homotopy. We use this invariant to show that there exist an infinite number of weak (1, 2, 3) homotopy equivalence classes of knot projections. By contrast, all equivalence classes of knot projections consisting of the other variants of a triple type, i.e. Reidemeister moves of (1, strong type 2, strong type 3), (1, weak type 2, strong type 3), and (1, strong type 2, weak type 3), are contractible.

本文言語English
論文番号1550069
ジャーナルInternational Journal of Mathematics
26
9
DOI
出版ステータスPublished - 2015 8 29
外部発表はい

ASJC Scopus subject areas

  • 数学 (全般)

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