Research
On-device research index

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.

168,695 papers · 148 categories

Trend · papers per month

87173260346 · May 202619922001200920172026
48 results for positive crossing changes

An oriented compact 4-manifold VV with boundary S3S^3 is called a positon (resp. negaton) if its intersection form is positive definite (resp. negative definite) and it is simply connected. In this paper, we prove that there exist infinitely many knots which cannot bound null-homologous disks either in positons or in …

2015-12-30abs ↗pdf ↗

We prove new results about unknotting fibered positive knots and braids.

problem Proving the unknotting number equals genus for fibered positive knots and braids.
method Analyzing positive braid diagrams and fibered positive knots, proving new constraints and conjectures.
result We found fibered positive knots that cannot be unknotted optimally, contradicting Stoimenow's conjecture.

Region crossing change is a local operation on link diagrams. The behavior of region crossing change on S2S^2 is well understood. In this paper, we study the behavior of (modified) region crossing change on higher genus surfaces.

2019-08-19abs ↗pdf ↗

In this note, we prove a lower bound for the positive kinkiness of a closed braid which we then use to derive an estimate for the positive kinkiness of a link in terms of its Seifert system. As an application, we show that certain pretzel knots cannot be unknotted using only positive crossing changes. We also describe …

2001-05-27abs ↗pdf ↗

Kearton observed that mutation can change the concordance class of a knot. A close examination of his example reveals that it is of 4-genus 1 and has a mutant of 4-genus 0. The first goal of this paper is to construct examples to show that for any pair of nonnegative integers m and n there is a knot of 4-genus m with a…

2003-10-07abs ↗pdf ↗

The paper explores when specific knot operations simplify diagrams.

problem Understanding when arc crossing changes simplify knot diagrams.
method Examined two types of arc crossing changes on link diagrams and determined when they are unknotting operations.
result Any two crossing points in an alternating knot diagram are arc crossing change admissible.

A region crossing change at a region of a spatial-graph diagram is a transformation changing every crossing on the boundary of the region. In this paper, it is shown that every spatial graph consisting of theta-curves can be unknotted by region crossing changes.

2019-10-27abs ↗pdf ↗

Spatial graphs of non-Eulerian or proper Eulerian planar graphs are unknottable by region crossing changes.

problem Unknottability of spatial graphs by region crossing changes.
method Region crossing changes to switch over/under relations within regions of spatial graph diagrams.
result Spatial graphs of non-Eulerian or proper Eulerian planar graphs are unknottable by region crossing changes.

In this paper, we prove that region crossing change on a link diagram is an unknotting operation if and only if the link is proper. A description of the behavior of region crossing change on link diagrams is given. Furthermore we also discuss the relation between region crossing change and the Arf invariant of proper l…

2012-01-09abs ↗pdf ↗

A knot in the 3-sphere is said to have zero negative unknotting number if it can be transformed into the unknot by performing only positive crossing changes. In this paper, we provide an obstruction for a knot to having zero negative unknotting number, and discuss its application to two classes of knots.

2016-04-07abs ↗pdf ↗

A crossing in a knot is nugatory if changing the crossing does not change the knot type. Using an invariant of certain types of closed 3-braid diagrams, we show that if a closed 3-braid contains a nugatory crossing then its braid index is one or two. This proves a special case of a conjecture on nugatory crossings due …

2010-01-10abs ↗pdf ↗

We show that if K is a satellite knot which admits a generalized cosmetic crossing change of order q with |q| \geq 6, then K admits a pattern knot with a generalized cosmetic crossing change of the same order. As a consequence of this, we find that any prime satellite knot which admits a pattern knot that is fibered ca…

2012-10-02abs ↗pdf ↗

Study analyzes market co-movements in critical mineral investments using change point detection and cross-sectional analysis.

problem Market dynamics in critical mineral investments during significant global events.
method Combines change-point detection (PELT algorithm) with cross-sectional analysis on ESG-ranked ETFs.
result Investors herded during market downturns and shifted to anti-herding after positive news and geopolitical shocks.

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 ↗

In a recent work of Ayaka Shimizu[5]^{[5]}, she defined an operation named region crossing change on link diagrams, and showed that region crossing change is an unknotting operation for knot diagrams. In this paper, we prove that region crossing change on a 2-component link diagram is an unknotting operation if and only…

2011-01-06abs ↗pdf ↗

In links with two components there are three different types of crossings: self-crossings in the first component, self crossings in the second component, and crossings between components. In this paper we examine the minimum number of crossing changes needed to unlink without changing the crossings between components. …

2019-06-29abs ↗pdf ↗

Let K' be a knot that admits no cosmetic crossing changes and let C be a non-trivial, prime, non-cable knot. Then any knot that is a satellite of C with winding number zero and pattern K' admits no cosmetic crossing changes. As a consequence we prove the nugatory crossing conjecture for Whitehead doubles of prime, non-…

2014-06-06abs ↗pdf ↗

We characterize cutting arcs on fiber surfaces that produce new fiber surfaces, and the changes in monodromy resulting from such cuts. As a corollary, we characterize band surgeries between fibered links and introduce an operation called Generalized Hopf banding. We further characterize generalized crossing changes bet…

2013-04-25abs ↗pdf ↗

Positive representations on surfaces have positive cross-ratios and satisfy a collar lemma.

problem Characterizing representations of surface groups with positive properties.
method Proving a collar lemma and showing positivity of cross-ratios for ΘΘ-positive representations.
result Closed subsets of representation varieties are characterized by ΘΘ-positive representations.

We use the Birman-Ko-Lee presentation of the braid group to show that all closures of strongly quasipositive braids whose normal form contains a positive power of the dual Garside element δδ are fibered. We classify links which admit such a braid representative in geometric terms as boundaries of plumbings of positive…

2016-10-30abs ↗pdf ↗

We prove that the property of admitting no cosmetic crossing changes is preserved under the operation of forming certain satellites of winding number zero. We also define strongly cosmetic crossing changes and we discuss their behavior under the operation of inserting full twists in the strings of closed braids.

2013-01-27abs ↗pdf ↗

Cross-validation pitfalls in change-point regression are addressed with new approaches.

problem Cross-validation's prediction error-based criterion may lead to under- or over-estimation of change-points.
method Proposes two approaches: absolute error loss and modified holdout sets.
result Consistent estimation of the number of change-points under certain conditions.

Unknotting numbers for torus knots and links are well known. In this paper, we present a method for determining the position of unknotting number crossing changes in a toric braid B(p, q) such that the closure of the resultant braid is equivalent to the trivial knot or link. Also, we provide a simple proof for the impo…

2012-07-20abs ↗pdf ↗

We show that the following unlinking strategy does not always yield an optimal sequence of crossing changes: first split the link with the minimal number of crossing changes, and then unknot the resulting components.

2014-10-08abs ↗pdf ↗

Study of disks in complex projective space with specific fundamental groups.

problem Locally flat disks with boundary a fixed knot in (CP2)(\mathbb{C} P^2)^\circ with Z\mathbb{Z}-fundamental group.
method Topological isotopy, crossing changes, and algebraic invariants.
result Existence and classification of Z\mathbb{Z}-disks in (CP2)(\mathbb{C} P^2)^\circ.