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Mostrando ítems 1-10 de 15
Artículo
Triangle-Free Planar Graphs as Segments Intersection Graphs
(1999)
We prove that every triangle-free planar graph is the graph of intersection of a set of segments in the plane. Moreover, the segments can be chosen in only three directions (horizontal, vertical and oblique) and in such a ...
Artículo
Embedding a graph in the grid of a surface with the minimum number of bends is NP-hard
(1997)
This paper is devoted to the study of graph embeddings in the grid of non-planar surfaces. We provide an adequate model for those embeddings and we study the complexity of minimizing the number of bends. In particular, we ...
Artículo
Cover Contact Graphs
(2007)
We study problems that arise in the context of covering certain geometric objects (so-called seeds, e.g., points or disks) by a set of other geometric objects (a so-called cover, e.g., a set of disks or homothetic triangles). ...
Capítulo de Libro
Reusing integer homology information of binary digital images
(2006)
In this paper, algorithms for computing integer (co)homology of a simplicial complex of any dimension are designed, extending the work done in [1,2,3]. For doing this, the homology of the object is encoded in an ...
Capítulo de Libro
Algebraic topological analysis of time-sequence of digital images
(2005)
This paper introduces an algebraic framework for a topological analysis of time-varying 2D digital binary–valued images, each of them defined as 2D arrays of pixels. Our answer is based on an algebraic-topological coding, ...
Capítulo de Libro
A Mathematica Notebook for Computing the Homology of Iterated Products of Groups
(2006)
Let G be a group which admits the structure of an iterated product of central extensions and semidirect products of abelian groups G i (both finite and infinite). We describe a Mathematica 4.0 notebook for computing the ...
Capítulo de Libro
Labeling Subway Lines
(2001)
Graphical features on map, charts, diagrams and graph drawings usually must be annotated with text labels in order to convey their meaning. In this paper we focus on a problem that arises when labeling schematized maps, ...
Capítulo de Libro
An algorithm for computing cocyclic matrices developed over some semidirect products
(2001)
An algorithm for calculating a set ofgenerators ofrepresentative 2-cocycles on semidirect product offinite abelian groups is constructed, in light ofthe theory over cocyclic matrices developed by Horadam and de Launey in ...
Artículo
On a visibility representation of graphs
(1996)
We give a visibility representation of graphs which extends some very well-known representations considered extensively in the literature. Concretely, the vertices are represented by a collection of parallel hyper-rectangles ...
Capítulo de Libro
Using membrane computing for obtaining homology groups of binary 2D digital images
(2009)
Membrane Computing is a new paradigm inspired from cellular communication. Until now, P systems have been used in research areas like modeling chemical process, several ecosystems, etc. In this paper, we apply P systems ...