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Using the band representation of the 3-strand braid group, it is shown that the genus of 3-braid links can be read off their skein polynomial. Some applications are given, in particular a simple proof of Morton's conjectured inequality and…

Geometric Topology · Mathematics 2008-08-30 A. Stoimenow

We give an $\mathcal{O}(n \log n)$-time, $\mathcal{O}(n)$-space algorithm for factoring a string into the minimum number of palindromic substrings. That is, given a string $S [1..n]$, in $\mathcal{O}(n \log n)$ time our algorithm returns…

Data Structures and Algorithms · Computer Science 2020-12-15 Gabriele Fici , Travis Gagie , Juha Kärkkäinen , Dominik Kempa

We introduce virtual tribrackets, an algebraic structure for coloring regions in the planar complement of an oriented virtual knot or link diagram. We use these structures to define counting invariants of virtual knots and links and provide…

Geometric Topology · Mathematics 2018-12-07 Sam Nelson , Shane Pico

Given a clique-width $k$-expression of a graph $G$, we provide $2^{O(k)}\cdot n$ time algorithms for connectivity constraints on locally checkable properties such as Node-Weighted Steiner Tree, Connected Dominating Set, or Connected Vertex…

Computational Complexity · Computer Science 2018-08-21 Benjamin Bergougnoux , Mamadou Moustapha Kanté

We described a simple algorithm running in linear time for each fixed constant $k$, that either establishes that the pathwidth of a graph $G$ is greater than $k$, or finds a path-decomposition of $G$ of width at most $O(2^{k})$. This…

Combinatorics · Mathematics 2009-09-25 Kevin Cattell , Michael J. Dinneen , Michael R. Fellows

Strong bisimilarity on normed BPA is polynomial-time decidable, while weak bisimilarity on totally normed BPA is NP-hard. It is natural to ask where the computational complexity of branching bisimilarity on totally normed BPA lies. This…

Logic in Computer Science · Computer Science 2014-11-18 Chaodong He

We show that for a number of parameterized problems for which only $2^{O(k)} n^{O(1)}$ time algorithms are known on general graphs, subexponential parameterized algorithms with running time $2^{O(k^{1-\frac{1}{1+\delta}} \log^2 k)}…

Data Structures and Algorithms · Computer Science 2016-10-26 Dániel Marx , Marcin Pilipczuk

We present a reduced Burau-like representation for the mixed braid group on one strand representing links in lens spaces and show how to calculate the Alexander polynomial of a link directly from the mixed braid.

Geometric Topology · Mathematics 2019-08-27 Boštjan Gabrovšek , Eva Horvat

We show that a non-trivial, non-central normal subgroup of the braid groups contains a braid whose closure is a hyperbolic knot with arbitrary large genus. This shows that non-faithfulness of a quantum representation implies that the…

Geometric Topology · Mathematics 2017-04-10 Tetsuya Ito

Two categorifications are given for the arrow polynomial, an extension of the Kauffman bracket polynomial for virtual knots. The arrow polynomial extends the bracket polynomial to infinitely many variables, each variable corresponding to an…

Geometric Topology · Mathematics 2010-05-07 Heather Ann Dye , Louis Hirsch Kauffman , Vassily Olegovich Manturov

We present a deterministic algorithm that given a tree T with n vertices, a starting vertex v and a slackness parameter epsilon > 0, estimates within an additive error of epsilon the cover and return time, namely, the expected time it takes…

Data Structures and Algorithms · Computer Science 2009-09-11 Uriel Feige , Ofer Zeitouni

We present the first polynomial-time algorithm to exactly compute the number of labeled chordal graphs on $n$ vertices. Our algorithm solves a more general problem: given $n$ and $\omega$ as input, it computes the number of…

Data Structures and Algorithms · Computer Science 2024-10-04 Ursula Hebert-Johnson , Daniel Lokshtanov , Eric Vigoda

We give a solution to the word problem for the singular braid monoid SB_n. The complexity of the algorithm is quadratic in the product of the word length and the number of the singular generators in the word. Furthermore we algebraically…

Geometric Topology · Mathematics 2007-05-23 Oliver T. Dasbach , Bernd Gemein

In this paper we provide two recognition algorithms for the class of signed-graphic matroids along with necessary and sufficient conditions for a matroid to be signed-graphic. Specifically, we provide a polynomial-time algorithm which…

Combinatorics · Mathematics 2012-05-08 Leonidas Pitsoulis , Konstantinos Papalamprou

A VB-algebroid is essentially defined as a Lie algebroid object in the category of vector bundles. There is a one-to-one correspondence between VB-algebroids and certain flat Lie algebroid superconnections, up to a natural notion of…

Differential Geometry · Mathematics 2011-09-30 Alfonso Gracia-Saz , Rajan Amit Mehta

We construct a pseudorandom generator which fools read-$k$ oblivious branching programs and, more generally, any linear length oblivious branching program, assuming that the sequence according to which the bits are read is known in advance.…

Computational Complexity · Computer Science 2017-08-08 Rohit Gurjar , Ben Lee Volk

Binets and trinets are phylogenetic networks with two and three leaves, respectively. Here we consider the problem of deciding if there exists a binary level-1 phylogenetic network displaying a given set $\mathcal{T}$ of binary binets or…

Data Structures and Algorithms · Computer Science 2014-11-26 Katharina Huber , Leo van Iersel , Vincent Moulton , Celine Scornavacca , Taoyang Wu

In the (binary) Distinct Vectors problem we are given a binary matrix A with pairwise different rows and want to select at most k columns such that, restricting the matrix to these columns, all rows are still pairwise different. A result by…

Computational Complexity · Computer Science 2023-06-22 Marcin Pilipczuk , Manuel Sorge

We propose an algorithm with expected complexity of $\bigO(n\log n)$ arithmetic operations to solve a special shortest vector problem arising in computer-and-forward design, where $n$ is the dimension of the channel vector. This algorithm…

Information Theory · Computer Science 2016-02-02 Jinming Wen , Xiao-Wen Chang

We present an $O(n^2)$-time algorithm to test whether an $n$-vertex directed partial $2$-tree is upward planar. This result improves upon the previously best known algorithm, which runs in $O(n^4)$ time.

Data Structures and Algorithms · Computer Science 2022-08-29 Steven Chaplick , Emilio Di Giacomo , Fabrizio Frati , Robert Ganian , Chrysanthi N. Raftopoulou , Kirill Simonov