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Related papers: Genera and crossing numbers of $2$-bridge knots

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Experimental work suggests that the Seifert genus of a knot grows linearly with respect to the crossing number of the knot. In this article, we use a billiard table model for $2$-bridge or rational knots to show that the average genus of a…

Geometric Topology · Mathematics 2025-08-19 Moshe Cohen , Adam M. Lowrance

The average genus of a 2-bridge knot with crossing number $c$ approaches $\frac{c}{4} + \frac{1}{12}$ as $c$ approaches infinity, as proven by Suzuki and Tran and independently Cohen and Lowrance. In this paper, for the genera of $2$-bridge…

Experimental data from Dunfield et al using random grid diagrams suggests that the genus of a knot grows linearly with respect to the crossing number. Using billiard table diagrams of Chebyshev knots developed by Koseleff and Pecker and a…

Geometric Topology · Mathematics 2021-08-03 Moshe Cohen

We determine a simple condition on a particular state graph of an alternating knot or link diagram that characterizes when the unoriented genus and crosscap number coincide, extending work of Adams and Kindred. Building on this same work…

Geometric Topology · Mathematics 2025-08-07 Moshe Cohen , Thomas Kindred , Adam M. Lowrance , Patrick D. Shanahan , Cornelia A. Van Cott

We present a practical algorithm to determine the minimal genus of non-orientable spanning surfaces for 2-bridge knots, called the crosscap numbers. We will exhibit a table of crosscap numbers of 2-bridge knots up to 12crossings (all 362 of…

Geometric Topology · Mathematics 2007-05-23 Mikami Hirasawa , Masakazu Teragaito

We show that the average or expected absolute value of the signatures of all 2-bridge knots with crossing number $c$ approaches $\sqrt{{2c}/{\pi}}$. Baader, Kjuchukova, Lewark, Misev, and Ray consider a model for 2-bridge knot diagrams…

Geometric Topology · Mathematics 2024-06-26 Moshe Cohen , Adam M. Lowrance , Neal Madras , Steven Raanes

In this article we study the braid indices of 2-bridge knots with a fixed crossing number $c$. We show that the average braid index of the set of $2$-bridge knots of crossing number $c$ is asymptotically linear, approaching…

Geometric Topology · Mathematics 2024-01-17 Tobias Clark , Jeremy Frank , Adam M. Lowrance

For any given number of crossings $c$, there exists a formula to determine the number of 2-bridge knots of $c$ crossings, and indeed it is a simple matter to actually construct presentations of these knots. However, the determination of…

Geometric Topology · Mathematics 2007-05-23 David De Wit

We prove that for 2-bridge knots, the diameter, D, of the set of boundary slopes is twice the crossing number, c. This constitutes partial verification of a conjecture that, for all knots in S^3, D is at most 2c.

Geometric Topology · Mathematics 2007-05-23 Thomas W. Mattman , Gabriel Maybrun , Kristin Robinson

In this paper, we enumerate the number of oriented rational knots and the number of oriented rational links with any given crossing number and minimum genus. This allows us to obtain a precise formula for the average minimal genus of…

Geometric Topology · Mathematics 2022-04-28 Dawn Ray , Yuanan Diao

In this paper, we consider two properties on the braid index of a two-bridge knot. We prove an inequality on the braid indices of two-bridge knots if there exists an epimorphism between their knot groups. Moreover, we provide the average…

Geometric Topology · Mathematics 2023-10-05 Masaaki Suzuki , Anh T. Tran

We have the generating function which determines the number of $2$-bridge knot groups admitting epimorphisms onto the knot group of a given $2$-bridge knot, in terms of crossing number. In this paper, we will refine this formula by taking…

Geometric Topology · Mathematics 2020-10-15 Masaaki Suzuki

Cohen, Lowrance, Madras, and Raanes computed the average (absolute value of) signature over all 2-bridge knots with crossing number $c$ by introducing the number $s(c,\sigma)$ of 2-bridge knots of crossing number $c$ and signature $\sigma$.…

Geometric Topology · Mathematics 2026-04-24 Cody Baker , Moshe Cohen , Henry Dam , Rebecca Felber , Neal Madras , Ritvik Saha , Daisy Thackrah

Suppose that there exists an epimorphism from the knot group of a $2$-bridge knot $K$ onto that of another knot $K'$. In this paper, we study the relationship between their crossing numbers $c(K)$ and $c(K')$. Especially it is shown that…

Geometric Topology · Mathematics 2018-03-16 Masaaki Suzuki

In a previous work, the first and third authors studied a random knot model for all two-bridge knots using billiard table diagrams. Here we present a closed formula for the distribution of the crossing numbers of such random knots. We also…

Geometric Topology · Mathematics 2018-08-13 Moshe Cohen , Chaim Even-Zohar , Sunder Ram Krishnan

In this short note we show the existence of an epimorphism between groups of $2$-bridge knots by means of an elementary argument using the Riley polynomial. As a corollary, we give a classification of $2$-bridge knots by Riley polynomials.

Geometric Topology · Mathematics 2016-09-27 Teruaki Kitano , Takayuki Morifuji

In this paper, we show the trivializing number of all minimal diagrams of positive 2-bridge knots and study the relation between the trivializing number and the unknotting number for a part of these knots.

Geometric Topology · Mathematics 2016-02-24 Kazuhiko Inoue

In this paper, we give the trivializing number of all minimal diagrams of positive 2-bridge knots, and study the relation between the trivializing number and the unknotting number for a part of these knots.

K-Theory and Homology · Mathematics 2015-12-08 Kazuhiko Inoue

Let $K,K'$ be two-bridge knots of genus $n,k$ respectively. We show the necessary and sufficient condition of $n$ in terms of $k$ that there exists an epimorphism from the knot group of $K$ onto that of $K'$.

Geometric Topology · Mathematics 2017-07-13 Masaaki Suzuki , Anh T. Tran

We give infinitely many examples of 2-bridge knots for which the topological and smooth slice genera differ. The smallest of these is the 12-crossing knot $12a255$. These also provide the first known examples of alternating knots for which…

Geometric Topology · Mathematics 2016-11-10 Peter Feller , Duncan McCoy
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