scholarly journals On the Combinatorial Structure of Arrangements of Oriented Pseudocircles

10.37236/1783 ◽  
2004 ◽  
Vol 11 (1) ◽  
Author(s):  
Johann Linhart ◽  
Ronald Ortner
Keyword(s):  
Representation Theorem ◽  
Equivalence Classes ◽  
Oriented Matroids ◽  
Combinatorial Structure ◽  
Topological Representation ◽  
Combinatorial Properties ◽  
One To One ◽  
Orientable Surfaces

We introduce intersection schemes (a generalization of uniform oriented matroids of rank 3) to describe the combinatorial properties of arrangements of pseudocircles in the plane and on closed orientable surfaces. Similar to the Folkman-Lawrence topological representation theorem for oriented matroids we show that there is a one-to-one correspondence between intersection schemes and equivalence classes of arrangements of pseudocircles. Furthermore, we consider arrangements where the pseudocircles separate the surface into two components. For these strict arrangements there is a one-to-one correspondence to a quite natural subclass of consistent intersection schemes.

scholarly journals Tropical Oriented Matroids

2012 ◽  
Vol DMTCS Proceedings vol. AR,... (Proceedings) ◽  
Author(s):  
Silke Horn
Keyword(s):  
Representation Theorem ◽  
Oriented Matroids ◽  
Oriented Matroid ◽  
Topological Representation ◽  
International Audience

International audience Tropical oriented matroids were defined by Ardila and Develin in 2007. They are a tropical analogue of classical oriented matroids in the sense that they encode the properties of the types of points in an arrangement of tropical hyperplanes – in much the same way as the covectors of (classical) oriented matroids describe the types in arrangements of linear hyperplanes. Not every oriented matroid can be realised by an arrangement of linear hyperplanes though. The famous Topological Representation Theorem by Folkman and Lawrence, however, states that every oriented matroid can be represented as an arrangement of $\textit{pseudo}$hyperplanes. Ardila and Develin proved that tropical oriented matroids can be represented as mixed subdivisions of dilated simplices. In this paper I prove that this correspondence is a bijection. Moreover, I present a tropical analogue for the Topological Representation Theorem. La notion de matroïde orientè tropical a été introduite par Ardila et Develin en 2007. Ils sont un analogue des matroïdes orientés classiques dans le sens où ils codent les propriétés des types de points dans un arrangement d'hyperplans tropicaux – d'une manière très similaire à celle dont les covecteurs des matroïdes orientés (classiques) décrivent les types de points dans les arrangements d'hyperplans linéaires. Tous les matroïdes orientés ne peuvent pas être représentés par un arrangement d'hyperplans linéaires. Cependant le célèbre théorème de représentation topologique de Folkman et Lawrence affirme que tout matroïde orientè peut être représenté par un arrangement de $\textit{pseudo}$-hyperplans. Ardila et Develin ont prouvè que les matroïdes orientés tropicaux peuvent être représentés par des sous-divisions mixtes de simplexes dilatés. Je prouve dans cet article que cette correspondance est une bijection. Je présente en outre, un analogue tropical du théorème de représentation topologique.

A CATALOGUE OF ORIENTABLE 3-MANIFOLDS TRIANGULATED BY 30 COLORED TETRAHEDRA

2008 ◽  
Vol 17 (05) ◽  
pp. 579-599 ◽  
Author(s):  
MARIA RITA CASALI ◽  
PAOLA CRISTOFORI
Keyword(s):  
Automatic Generation ◽  
Computational Approach ◽  
Equivalence Classes ◽  
Colored Graphs ◽  
One To One ◽  
Genus Two ◽  
Jsj Decompositions

The present paper follows the computational approach to 3-manifold classification via edge-colored graphs, already performed in [1] (with respect to orientable 3-manifolds up to 28 colored tetrahedra), in [2] (with respect to non-orientable 3-manifolds up to 26 colored tetrahedra), in [3] and [4] (with respect to genus two 3-manifolds up to 34 colored tetrahedra): in fact, by automatic generation and analysis of suitable edge-colored graphs, called crystallizations, we obtain a catalogue of all orientable 3-manifolds admitting colored triangulations with 30 tetrahedra. These manifolds are unambiguously identified via JSJ decompositions and fibering structures. It is worth noting that, in the present work, a suitable use of elementary combinatorial moves yields an automatic partition of the elements of the generated crystallization catalogue into equivalence classes, which turn out to be in one-to-one correspondence with the homeomorphism classes of the represented manifolds.

Nearnesses and T0-Extensions of Topological Spaces

1983 ◽  
Vol 26 (4) ◽  
pp. 430-437 ◽  
Author(s):  
Alice M. Dean
Keyword(s):  
Topological Space ◽  
Equivalence Classes ◽  
Topological Spaces ◽  
One To One

AbstractIn [3], Reed establishes a bijection between the (equivalence classes of) principal T1-extensions of a topological space X and the compatible, cluster-generated, Lodato nearnesses on X. We extend Reed's result to the T0 case by obtaining a one-to-one correspondence between the principal T0-extensions of a space X and the collections of sets (called “t-grill sets”) which generate a certain class of nearnesses which we call “t-bunch generated” nearnesses. This correspondence specializes to principal T0-compactifications. Finally, we show that there is a bijection between these t-grill sets and the filter systems of Thron [5], and that the corresponding extensions are equivalent.

scholarly journals Classification of fused links

2016 ◽  
Vol 25 (14) ◽  
pp. 1650076 ◽  
Author(s):  
Timur Nasybullov
Keyword(s):  
Symmetric Group ◽  
Equivalence Classes ◽  
One To One ◽  
Text Component

We construct the complete invariant for fused links. It is proved that the set of equivalence classes of [Formula: see text]-component fused links is in one-to-one correspondence with the set of elements of the abelization [Formula: see text] up to conjugation by elements from the symmetric group [Formula: see text].

Detecting Non-Triviality of Virtual Links

2003 ◽  
Vol 12 (06) ◽  
pp. 781-803 ◽  
Author(s):  
Teruhisa Kadokami
Keyword(s):  
Equivalence Classes ◽  
Geometric Method ◽  
Virtual Link ◽  
Virtual Knot ◽  
Stable Equivalence ◽  
Link Diagrams ◽  
Virtual Links ◽  
Algebraic Invariants ◽  
One To One

J. S. Carter, S. Kamada and M. Saito showed that there is one to one correspondence between the virtual Reidemeister equivalence classes of virtual link diagrams and the stable equivalence classes of link diagrams on compact oriented surfaces. Using the result, we show how to obtain the supporting genus of a projected virtual link by a geometric method. From this result, we show that a certain virtual knot which cannot be judged to be non-trivial by known algebraic invariants is non-trivial, and we suggest to classify the equivalence classes of projected virtual links by using the supporting genus.

Generating functions for finite group actions on surfaces

1998 ◽  
Vol 124 (1) ◽  
pp. 21-49 ◽  
Author(s):  
C. MACLACHLAN ◽  
A. MILLER
Keyword(s):  
Finite Group ◽  
Generating Function ◽  
Generating Functions ◽  
Isomorphism Class ◽  
Group Actions ◽  
Equivalence Classes ◽  
Topological Conjugacy ◽  
Finite Group Actions ◽  
Orientable Surfaces

For a fixed finite group G, the numbers Ng of equivalence classes of orientation-preserving actions of G on closed orientable surfaces Σg of genus g can be encoded by a generating function [sum ]Ngzg. When equivalence is determined by the isomorphism class of the quotient orbifold Σg/G, we show that the generating function is rational. When equivalence is topological conjugacy, we examine the cases where G is abelian and show that the generating function is again rational in the cases where G is cyclic.

scholarly journals Weighted Random Staircase Tableaux

2014 ◽  
Vol 23 (6) ◽  
pp. 1114-1147 ◽  
Author(s):  
PAWEŁ HITCZENKO ◽  
SVANTE JANSON
Keyword(s):  
General Model ◽  
Extreme Values ◽  
Exclusion Process ◽  
Combinatorial Structure ◽  
Asymmetric Exclusion Process ◽  
Urn Model ◽  
Eulerian Polynomials ◽  
Combinatorial Properties ◽  
Special Cases ◽  
Asymmetric Exclusion

This paper concerns a relatively new combinatorial structure called staircase tableaux. They were introduced in the context of the asymmetric exclusion process and Askey–Wilson polynomials; however, their purely combinatorial properties have gained considerable interest in the past few years.In this paper we further study combinatorial properties of staircase tableaux. We consider a general model of random staircase tableaux in which symbols (Greek letters) that appear in staircase tableaux may have arbitrary positive weights. (We consider only the case with the parametersu=q= 1.) Under this general model we derive a number of results. Some of our results concern the limiting laws for the number of appearances of symbols in a random staircase tableaux. They generalize and subsume earlier results that were obtained for specific values of the weights.One advantage of our generality is that we may let the weights approach extreme values of zero or infinity, which covers further special cases appearing earlier in the literature. Furthermore, our generality allows us to analyse the structure of random staircase tableaux, and we obtain several results in this direction.One of the tools we use is the generating functions of the parameters of interest. This leads us to a two-parameter family of polynomials, generalizing the classical Eulerian polynomials.We also briefly discuss the relation of staircase tableaux to the asymmetric exclusion process, to other recently introduced types of tableaux, and to an urn model studied by a number of researchers, including Philippe Flajolet.

scholarly journals Double coverings of twisted links

2016 ◽  
Vol 25 (09) ◽  
pp. 1641011 ◽  
Author(s):  
Naoko Kamada ◽  
Seiichi Kamada
Keyword(s):  
Equivalence Classes ◽  
Double Covering ◽  
Virtual Knot ◽  
Stable Equivalence ◽  
Virtual Links ◽  
Orientable Surfaces ◽  
Double Coverings

Twisted links are a generalization of virtual links. As virtual links correspond to abstract links on orientable surfaces, twisted links correspond to abstract links on (possibly non-orientable) surfaces. In this paper, we introduce the notion of the double covering of a twisted link. It is defined by considering the orientation double covering of an abstract link or alternatively by constructing a diagram called a double covering diagram. We also discuss links in thickened surfaces, their diagrams and their stable equivalence classes. Bourgoin’s twisted knot group is understood as the virtual knot group of the double covering.

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