Research ArticleNo Access

Computing with knot quandles

Graham Ellis

http://orcid.org/0000-0003-4960-3796

School of Mathematics, National University of Ireland, Galway, Ireland

Département Génie Mathématique, Institut National des Sciences Appliquées, Rouen, France

E-mail Address: graham.ellis@nuigalway.ie

Corresponding author.

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and

Cédric Fragnaud

School of Mathematics, National University of Ireland, Galway, Ireland

Département Génie Mathématique, Institut National des Sciences Appliquées, Rouen, France

E-mail Address: cedric.fragnaud@insa-rouen.fr

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https://doi.org/10.1142/S0218216518500748Cited by:1 (Source: Crossref)

Abstract

The number ${Col}_{Q} (K)$ of colorings of a knot $K$ by a finite quandle $Q$ has been used in the literature to distinguish between knot types. In this paper, we suggest a refinement ${Col}_{Q}^{F} (K)$ to this knot invariant involving any computable functor $F$ from finitely presented groups to finitely generated abelian groups. We are mainly interested in the functor $F =^{a b}$ that sends each finitely presented group $H$ to its abelianization $H^{a b} = H / [H . H]$ . We describe algorithms needed for computing the refined invariant and illustrate implementations that have been made available as part of the HAP package for the GAP system for computational algebra. We use these implementations to investigate the performance of the refined invariant on prime knots with $\leq 11$ crossings.

Keywords:

AMSC: 57M25, 57M27

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