arXiv subjects

Nancy C. Wrinkle

Publications and source records attributed to Nancy C. Wrinkle.

5 recordsLinked to original sources

arXiv2021

Distance and intersection number in the curve graph of a surface

In this work, we study the cellular decomposition of $S$ induced by a filling pair of curves $v$ and $w$, $Dec_{v,w}(S) = S - (v \cup w)$, and its connection to the distance function $d(v,w)$ in the curve graph of a closed orientable surface $S$ of genus $g$. Efficient geodesics were introduced by the first author in joint work with Margalit and Menasco in 2016, giving an algorithm that begins with a pair of non-separating filling curves that determine vertices $(v,w)$ in the curve graph of a closed orientable surface $S$ and computing from them a finite set of efficient geodesics. We extend the tools of efficient geodesics to study the relationship between distance $d(v,w)$, intersection number $i(v,w)$, and $Dec_{v,w}(S)$. The main result is the development and analysis of particular configurations of rectangles in $Dec_{v,w}(S)$ called spirals. We are able to show that, in some special cases, the efficient geodesic algorithm can be used to build an algorithm that reduces $i(v,w)$ while preserving $d(v,w)$. At the end of the paper, we note a connection of our work to the notion of extending geodesics.

math.GT↗

arXiv2005

Some Ropelength-Critical Clasps

We describe several configurations of clasped ropes which are balanced and thus critical for the Gehring ropelength problem of arXiv:math.DG/0402212.

math.DG↗

arXiv2002

The Markov Theorem for transverse knots

A transverse knot is a knot that is transverse to the planes of the standard contact structure on real 3-space. In this paper we prove the Markov Theorem for transverse braids, which states that two transverse closed braids that are isotopic as transverse knots are also isotopic as transverse braids. The methods of the proof are based on Birman and Menasco's proof of the Markov Theorem in their recent paper (BM02), modified to the transverse setting. The modification is straightforward until we get to the special case of preferred longitudes, where we need some new machinery. We use techniques from earlier work by the author with Birman (BW00), by Birman and Menasco ((BM4), for example), and develop new methods from Cromwell's paper on arc-presentations (Cr95).

math.GT↗

arXiv2001

On transversally simple knots

Final revision. To appear in the Journal of Differential Geometry. This paper studies knots that are transversal to the standard contact structure in $\reals^3$, bringing techniques from topological knot theory to bear on their transversal classification. We say that a transversal knot type $\cTK$ is {\it transversally simple} if it is determined by its topological knot type $\cK$ and its Bennequin number. The main theorem asserts that any $\cTK$ whose associated $\cK$ satisfies a condition that we call {\em exchange reducibility} is transversally simple. As a first application, we prove that the unlink is transversally simple, extending the main theorem in \cite{El}. As a second application we use a new theorem of Menasco (Theorem 1 of \cite{Me}) to extend a result of Etnyre \cite{Et} to prove that iterated torus knots are transversally simple. We also give a formula for their maximum Bennequin number. We show that the concept of exchange reducibility is the simplest of the constraints that one can place on $\cK$ in order to prove that any associated $\cTK$ is transversally simple. We also give examples of pairs of transversal knots that we conjecture are {\em not} transversally simple.

math.GT↗

arXiv2000

Holonomic and Legendrian parametrizations of knots

Let $f:S^1\to R$ be a generic map. We may use $f$ to define a new map $\tilde{f}:S^1\to R^3$ by $\tilde{f}(t) = (-f(t),f'(t),-f''(t))$, and if $f$ is an embedding then the image of $\tilde{f}$ will be a knot. Knots defined by such parametrizations are called holonomic knots. They were introduced in 1997 by Vassiliev, who proved that every knot type can be represented by a holonomic knot. Our main result is that any two holonomic knots which represent the same knot type are isotopic in the space of holonomic knots. A second result emerges through the techniques used to prove the main result: strong and unexpected connections between the topology of knots and the algebraic solution to the conjugacy problem in the braid groups, via the work of Garside. We also discuss related parametrizations of Legendrian knots, and uncover connections between the concepts of holonomic and Legendrian parametrizations of knots.

math.GT↗