Segment number of knots
In this paper, we introduce a new numerical knot invariant, termed the segment number, which is derived from partitioned knot diagrams subject to specific over/under-crossing constraints. We prove that a knot is non-trivial if and only if its segment number is at least 3. Furthermore, we investigate the structural properties of the directed graph associated with a minimal segment number presentation. Specifically, we show that for any minimal presentation, the underlying graph is connected and cannot be a path. Finally, we discuss the relationship between the segment number and the bridge number, providing bounds and conjectures for future study. We also conjecture that the bridge number [Formula: see text] provides a lower bound for the segment number.
Authors
- Makoto Ozawa (ORCID: https://orcid.org/0000-0001-7297-0530)
Institutions
- Komazawa University (JP)
Publication Details
- Journal
- Journal of Knot Theory and Its Ramifications
- Published
- 2026-02-27
- DOI
- https://doi.org/10.1142/s0218216526500215
- Primary Topic
- Geometric and Algebraic Topology
- Type
- article
- Field-Weighted Citation Impact
- 0.00