Height, trunk and representativity of knots

• Blair Ryan

  Department of Mathematics California State University

• Ozawa Makoto

  Department of Natural Sciences Faculty of Arts and Sciences Komazawa University

Abstract

In this paper, we investigate three geometrical invariants of knots, the height, the trunk and the representativity. First, we give a counterexample for the conjecture which states that the height is additive under connected sum of knots. We also define the minimal height of a knot and give a potential example which has a gap between the height and the minimal height. Next, we show that the representativity is bounded above by a half of the trunk. We also define the trunk of a tangle and show that if a knot has an essential tangle decomposition, then the representativity is bounded above by half of the trunk of either of the two tangles. Finally, we remark on the difference among Gabai's thin position, ordered thin position and minimal critical position. We also give an example of a knot which bounds an essential non-orientable spanning surface, but has arbitrarily large representativity.

Journal

• Journal of the Mathematical Society of Japan

  Journal of the Mathematical Society of Japan 71 (4), 1105-1121, 2019

  The Mathematical Society of Japan

Keywords

• knot
• height
• trunk
• representativity
• waist

Details

• CRID: 1390564227327661952
• NII Article ID: 130007733312
• NII Book ID: AA0070177X
• DOI: 10.2969/jmsj/80438043
• ISSN: 18811167
• ISSN: 18812333
• ISSN: 00255645
• NDL BIB ID: 030030163
• Web Site: http://id.ndl.go.jp/bib/030030163
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I030030163
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed