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arXiv research

A locally-built, LLM-digested index of recent arXiv papers in quant finance, geometry/topology, and statistical ML — keyword search served straight from SQLite on this machine.

168,657 papers · 148 categories

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48 results for crossing number

The aim of the present paper is to prove that the minimal number of virtual crossings for some families of virtual knots grows quadratically with respect to the minimal number of classical crossings. All previously known estimates for virtual crossing number were principally no more than linear in the number of classic…

2011-07-25abs ↗pdf ↗

Spatial embeddings of planar graphs can have higher unknotting numbers than crossing numbers.

problem Understanding the relationship between unknotting numbers and crossing numbers of spatial embeddings of planar graphs.
method Analyzing specific examples of planar graphs and their spatial embeddings to find counterexamples.
result There exist planar graphs and their spatial embeddings where the unknotting number is greater than half the crossing number.

It is known that the arc index of alternating knots is the minimal crossing number plus two and the arc index of prime nonalternating knots is less than or equal to the minimal crossing number. We study some cases when the arc index is strictly less than the minimal crossing number. We also give minimal grid diagrams o…

2011-06-13abs ↗pdf ↗

In this paper we investigate the unlinking numbers of 10-crossing links. We make use of various link invariants and explore their behaviour when crossings are changed. The methods we describe have been used previously to compute unlinking numbers of links with crossing number at most 9. Ultimately, we find the unlinkin…

2017-01-05abs ↗pdf ↗

A quadruple crossing is a crossing in a projection of a knot or link that has four strands of the knot passing straight through it. A quadruple crossing projection is a projection such that all of the crossings are quadruple crossings. In a previous paper, it was proved that every knot and link has a quadruple crossing…

2012-11-12abs ↗pdf ↗

Study minimizes crossing points of up to 12 curves on a genus 2 surface.

problem Minimizing intersection points of curves on a surface.
method Analyzes systems of up to 12 simple closed curves on a genus 2 surface to find the minimum crossing number.
result Determines the minimal crossing number of up to 12 curves on a genus 2 surface and proves the minimization systems are unique.

The paper studies how the crossing number of graphs changes with a specific transformation called ΔY-move.

problem Investigating how the crossing number of graphs changes under the ΔY-move transformation.
method Analyzing the behavior of crossing number under the ΔY-move transformation on complete graphs.
result For any natural number k, there exists a sequence of ΔY-moves that decreases the crossing number of a complete graph.

An nn-crossing is a point in the projection of a knot where nn strands cross so that each strand bisects the crossing. An übercrossing projection has a single nn-crossing and a petal projection has a single nn-crossing such that there are no loops nested within others. The übercrossing number, u¨(K)\text{ü}(K), is the…

2013-11-03abs ↗pdf ↗

The paper defines and calculates an upper bound for the equivariant crossing number of two-bridge knots.

problem Finding the minimum number of crossings in symmetric diagrams for two-bridge knots.
method Defining and calculating c2(K)c_2(K) for two-bridge knots by restricting diagrams to two types.
result An algorithm to determine c2(K)c_2(K) for any two-bridge knot and results up to 14 crossings.

Study on knot properties, showing relation between unknotting and crossing numbers.

problem Relations between unknotting and crossing numbers of spatial embeddings.
method Analyzes handcuff-graphs and theta curves, extends known results to handlebody-knots.
result Characterizes handlebody-knots satisfying the equality between unknotting and crossing numbers.

A new knot invariant measures crossings in three orthogonal directions.

problem Defining a new knot invariant for certain knot diagrams.
method Defining the simultaneous crossing number for knots with doubly transvergent diagrams.
result The limit of the ratio of the new invariant to the usual crossing number is at most 8.

Traditionally, knot theorists have considered projections of knots where there are two strands meeting at every crossing. A triple crossing is a crossing where three strands meet at a single point, such that each strand bisects the crossing. In this paper we find a relationship between the triple crossing number and th…

2018-05-11abs ↗pdf ↗

Every link in the 3-sphere has a projection to the plane where the only singularities are pairwise transverse triple points. The associated diagram, with height information at each triple point, is a triple-crossing diagram of the link. We give a set of diagrammatic moves on triple-crossing diagrams analogous to the Re…

2017-06-28abs ↗pdf ↗

The paper tabulates and computes the number of alternating pretzel links up to a given crossing number.

problem Computing the total number of alternating pretzel links for a given crossing number.
method Derived a closed formula to compute the total number of alternating pretzel links, P(c)\mathcal{P}(c), for any given crossing number cc.
result The number of alternating pretzel links grows exponentially with the crossing number.

The paper improves bounds on knot crossings and tabulates minimal diagrams.

problem Improving bounds on knot crossings and tabulating minimal diagrams.
method Analyzing triple-crossing and delta-crossing numbers, proving tangle existence, generating tables.
result Improved bounds on knot crossings and tabulated minimal diagrams for prime knots up to delta-crossing number 4.

A multi-crossing (or n-crossing) is a singular point in a projection at which n strands cross so that each strand bisects the crossing. We generalize the classic result of Kauffman, Murasugi, and Thistlethwaite, which gives the upper bound on the span of the bracket polynomial of K as 4c_2(K), to the n-crossing number:…

2014-07-16abs ↗pdf ↗

A triple crossing is a crossing in a projection of a knot or link that has three strands of the knot passing straight through it. A triple crossing projection is a projection such that all of the crossings are triple crossings. We prove that every knot and link has a triple crossing projection and then investigate c_3(…

2012-07-31abs ↗pdf ↗

Study of generalized knots and links, proving inequality involving crossing number and braid index.

problem Proving an inequality involving the minimal crossing number and braid index for generalized knots and links.
method Introducing generalized crossings and moves, proving inequality for generalized knots and links.
result Proved inequality involving total crossing number and braid index for generalized knots and links.

The paper studies knots formed by twisting a circle around a base knot and conjectures a linear growth in crossing numbers.

problem Understanding the growth rate of crossing numbers in twist families of knots.
method Introduced the stable crossing number and used geometric wrapping and algebraic winding to establish conjectures.
result The crossing number of KnK_n grows like nη(η1)n η(η-1) as non o \infty for coherent twist families.

New strict inequalities for knot crossing numbers proved.

problem Establishing strict inequalities between different crossing numbers of knots.
method Proving and generalizing inequalities between nn-crossing numbers for various knots.
result Optimal strict inequality c9(K)c3(K)2c_9(K) \leq c_3(K) - 2 for many knots, with optimality proven.

The purpose of this article is to give a preliminary clarification on the relation between crossing number and crossing change. With a main focus on the span of X polynomial, we prove that, as our theorem claims, the crossing number of the link after crossing change can be estimated when certain conditions are met. At …

2011-03-24abs ↗pdf ↗

Enumerates knots up to five crossings and describes moves between them.

problem Counting and classifying knots up to a specific number of crossings.
method Generated tables of minimal diagrams and derived moves between knots.
result Conjecture about a lower bound for the triple-crossing number based on Alexander polynomial.

In this paper we compute the sharp lower bounds for the crossing number of nn-string kk-loop essential tangles. For essential tangles with only string components, we characterise the ones with the minimum crossing number for a given number of components, both when the tangle has knotted strings or only unknotted stri…

2015-05-27abs ↗pdf ↗