On the symmetric braid index of ribbon knots

Vitalijs Brejevs; Feride Ceren Kose

doi:10.1017/s0305004125101424

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arXiv · 2410.14884

On the symmetric braid index of ribbon knots

Vitalijs Brejevs·Feride Ceren Kose

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Abstract

We define the symmetric braid index $b_s(K)$ of a ribbon knot $K$ to be the smallest index of a braid whose closure yields a symmetric union diagram of $K$, and derive a Khovanov-homological characterisation of knots with $b_s(K)$ at most three. As applications, we show that there exist knots whose symmetric braid index is strictly greater than the braid index, and deduce that every chiral slice knot with determinant one has braid index at least four. We also calculate bounds for $b_s(K)$ for prime ribbon knots with at most 11 crossings.

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BibTeX RIS

Vitalijs Brejevs, Feride Ceren Kose. 2024-10-18. On the symmetric braid index of ribbon knots. https://doi.org/10.1017/s0305004125101424

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