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The basic (and traditional) crossing number problem is to determine the minimum number of crossings in a topological drawing of an input graph in the plane. We develop a unified framework yielding fixed-parameter tractable (FPT) algorithms…

Computational Geometry · Computer Science 2026-05-07 Éric Colin de Verdière , Petr Hliněný

The decoding problem is a ubiquitous algorithmic task in fault-tolerant quantum computing, and solving it efficiently is essential for scalable quantum computing. Here, we prove that minimum-weight decoding is NP-hard in three…

Quantum Physics · Physics 2026-03-24 Shouzhen Gu , Lily Wang , Aleksander Kubica

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…

Geometric Topology · Mathematics 2018-05-14 Daishiro Nishida

The problem of P vs. NP is very serious, and solutions to the problem can help save lives. This article is an attempt at solving the problem using a computer algorithm. It is presented in a fashion that will hopefully allow for easy…

Data Structures and Algorithms · Computer Science 2015-03-19 Matt Groff

The concordance genus of a knot K is the minimum three-genus among all knots concordant to K. For prime knots of 10 or fewer crossings there have been three knots for which the concordance genus was unknown. Those three cases are now…

Geometric Topology · Mathematics 2014-10-01 Charles Livingston

Efficient encoding of classical data into quantum state -- currently referred to as quantum encoding -- holds crucial significance in quantum computation. For finite-size databases and qubit registers, a common strategy of the quantum…

Quantum Physics · Physics 2025-08-05 Jaehee Kim , Taewan Kim , Kyunghyun Baek , Yongsoo Hwang , Joonsuk Huh , Jeongho Bang

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…

We introduce a new real-valued invariant called the natural slope of a hyperbolic knot in the 3-sphere, which is defined in terms of its cusp geometry. We show that twice the knot signature and the natural slope differ by at most a constant…

Geometric Topology · Mathematics 2024-09-04 Alex Davies , András Juhász , Marc Lackenby , Nenad Tomasev

Graph Crossing Number is a fundamental problem with various applications. In this problem, the goal is to draw an input graph $G$ in the plane so as to minimize the number of crossings between the images of its edges. Despite extensive…

Data Structures and Algorithms · Computer Science 2021-01-12 Julia Chuzhoy , Sepideh Mahabadi , Zihan Tan

Given an edge-weighted graph $G$ on $n$ nodes, the NP-hard Max-Cut problem asks for a node bipartition such that the sum of edge weights joining the different partitions is maximized. We propose a fixed-parameter tractable algorithm…

Data Structures and Algorithms · Computer Science 2020-07-23 Markus Chimani , Christine Dahn , Martina Juhnke-Kubitzke , Nils M. Kriege , Petra Mutzel , Alexander Nover

The scramble number of a graph is an invariant recently developed to study chip-firing games and divisorial gonality. In this paper we introduce the screewidth of a graph, based on a variation of the existing literature on tree-cut…

A unicellular map is the embedding of a connected graph in a surface in such a way that the complement of the graph is a topological disk. In this paper we present a bijective link between unicellular maps on a non-orientable surface and…

Combinatorics · Mathematics 2012-04-20 Olivier Bernardi , Guillaume Chapuy

Gr\"obner bases can be used for computing the Hilbert basis of a numerical submonoid. By using these techniques, we provide an algorithm that calculates a basis of a subspace of a finite-dimensional vector space over a finite prime field…

Algebraic Geometry · Mathematics 2013-03-27 Natalia Dück , Karl-Heinz Zimmermann

An $n$-crossing is a point in the projection of a knot where $n$ strands cross so that each strand bisects the crossing. An \"ubercrossing projection has a single $n$-crossing and a petal projection has a single $n$-crossing such that there…

Understanding entanglement cost in non-local quantum computation (NLQC) is relevant to complexity, cryptography, gravity, and other areas. This entanglement cost is largely uncharacterized; previous lower bound techniques apply to narrowly…

Quantum Physics · Physics 2026-05-01 Richard Cleve , Alex May

Active quantum error correction has been identified as a crucial ingredient of future quantum computers, motivating the recent experimental efforts to encode logical quantum bits using small topological codes. In addition to the…

Quantum Physics · Physics 2019-03-06 M. Gutiérrez , M. Müller , A. Bermudez

A branched covering surface-knot is a surface-knot in the form of a branched covering over a surface-knot. For a branched covering surface-knot, we have a numerical invariant called the simplifying number. We show that branched covering…

Geometric Topology · Mathematics 2019-02-07 Inasa Nakamura

Let $\mathcal{A}$ be a set of straight lines in the plane (or planes in $\mathbb{R}^3$). The $k$-crossing visibility of a point $p$ on $\mathcal{A}$ is the set $Q$ of points in the elements of $\mathcal{A}$ such that the segment $pq$, where…

Computational Geometry · Computer Science 2024-05-17 Frank Duque

Physical knot classification is a challenging fine-grained recognition task in which the intended discriminative cue is rope crossing structure; however, high closed-set accuracy may still arise from low-level appearance shortcuts rather…

Computer Vision and Pattern Recognition · Computer Science 2026-04-23 Shiheng Nie , Yunguang Yue

We introduce a geometric invariant of knots in the three-sphere, called the first-order genus, that is derived from certain 2-complexes called gropes, and we show it is computable for many examples. While computing this invariant, we draw…

Geometric Topology · Mathematics 2009-11-13 Peter Horn