Stabilization in the braid groups I: MTWS

Joan S Birman; William W Menasco

doi:10.2140/gt.2006.10.413

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Stabilization in the braid groups I: MTWS

Joan S Birman·William W Menasco

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Abstract

Choose any oriented link type X and closed braid representatives X[+], X[-] of X, where X[-] has minimal braid index among all closed braid representatives of X. The main result of this paper is a `Markov theorem without stabilization'. It asserts that there is a complexity function and a finite set of `templates' such that (possibly after initial complexity-reducing modifications in the choice of X[+] and X[-]which replace them with closed braids X[+]', X[-]') there is a sequence of closed braid representatives X[+]' = X^1->X^2->...->X^r = X[-]' such that each passage X^i->X^i+1 is strictly complexity reducing and non-increasing on braid index. The templates which define the passages X^i->X^i+1 include 3 familiar ones, the destabilization, exchange move and flype templates, and in addition, for each braid index m>= 4 a finite set T(m) of new ones. The number of templates in T(m) is a non-decreasing function of m. We give examples of members of T(m), m>= 4, but not a complete listing. There are applications to contact geometry, which will be given in a separate paper.

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BibTeX RIS

Joan S Birman, William W Menasco. 2009-02-26. Stabilization in the braid groups I: MTWS. https://doi.org/10.2140/gt.2006.10.413

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