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Showing papers on "Adjacency list published in 1999"


Journal ArticleDOI
TL;DR: This paper presents crossover and mutation operators, developed to tackle the Travelling Salesman Problem with Genetic Algorithms with different representations such as: binary representation, path representation, adjacency representation, ordinal representation and matrix representation.
Abstract: This paper is the result of a literature study carried out by the authors. It is a review of the different attempts made to solve the Travelling Salesman Problem with Genetic Algorithms. We present crossover and mutation operators, developed to tackle the Travelling Salesman Problem with Genetic Algorithms with different representations such as: binary representation, path representation, adjacency representation, ordinal representation and matrix representation. Likewise, we show the experimental results obtained with different standard examples using combination of crossover and mutation operators in relation with path representation.

839 citations


Journal ArticleDOI
TL;DR: In this article, the optimal configuration of all 40 fullerene isomers of C40, using methods from molecular mechanics and tight-binding to full abinitio SCF and DFT approaches, confirms minimisation of pentagon adjacency as a major factor in relative stability.
Abstract: Optimisation of geometries of all 40 fullerene isomers of C40, using methods from molecular mechanics and tight-binding to full abinitio SCF and DFT approaches, confirms minimisation of pentagon adjacency as a major factor in relative stability. The consensus predictions of 11 out of 12 methods are that the isomer of lowest total energy is the D2 cage with the smallest possible adjacency count, and that energies rise linearly with the number of adjacencies. Quantum mechanical methods predict a slope of 80–100 kJ mol-1 per adjacency. Molecular mechanics methods are outliers, with the Tersoff potential giving a different minimum and its Brenner modification a poor correlation and much smaller penalty.

183 citations


Journal ArticleDOI
TL;DR: In this article, a dynamic layout construction procedure is presented, in which resources, represented as rectangles, are subjected to two-dimensional geometric constraints on relative locations, and a linear program is solved to find feasible positions for each resource.
Abstract: Efficiently using site space to accommodate resources throughout the duration of a construction project is a critical problem. It is termed the “dynamic layout planning” problem. Solving it involves creating a sequence of layouts that span the entire project duration, given resources, the timing of their presence on site, their changing demand for space over time, constraints on their location, and costs for their relocation. A dynamic layout construction procedure is presented here. Construction resources, represented as rectangles, are subjected to two-dimensional geometric constraints on relative locations. The objective is to allow site space to all resources so that no spatial conflicts arise, while keeping distance-based adjacency and relocation costs minimal. The solution is constructed stepwise for consecutive time frames. For each resource, selected heuristically one at a time, constraint satisfaction is used to compute sets of feasible positions. Subsequently, a linear program is solved to find ...

171 citations


Journal ArticleDOI
TL;DR: This work presents a new approach for automatic hexahedral meshing, based on the embedded Voronoi graph, which provides complete information regarding proximity and adjacency relationships between the entities of the volume.
Abstract: This work presents a new approach for automatic hexahedral meshing, based on the embedded Voronoi graph. The embedded Voronoi graph contains the full symbolic information of the Voronoi diagram and the medial axis of the object, and a geometric approximation to the real geometry. The embedded Voronoi graph is used for decomposing the object, with the guiding principle that resulting sub-volumes are sweepable. Sub-volumes are meshed independently, and the resulting meshes are easily combined and smoothed to yield the final mesh. The approach presented here is general and automatic. It handles any volume, even if its medial axis is degenerate. The embedded Voronoi graph provides complete information regarding proximity and adjacency relationships between the entities of the volume. Hence, decomposition faces are determined unambiguously, without any further geometric computations. The sub-volumes computed by the algorithm are guaranteed to be well-defined and disjoint. The size of the decomposition is relatively small, since every sub-volume contains a different Voronoi face. Mesh quality seems high since the decomposition avoids generation of sharp angles, and sweep and other basic methods are used to mesh the sub-volumes.

95 citations


Journal ArticleDOI
TL;DR: In this paper, it is shown that each plane graph without 4-cycles is 4-choosable.

87 citations


Journal ArticleDOI
TL;DR: This paper focuses on efficiently encoding and decoding the stitching information, and avoids encoding vertices (and properties bound to vertices) multiple times; thus a reduction of the size of the bit-stream of about 10% is obtained compared with encoding the model as a manifold.
Abstract: We present a method for compressing non-manifold polygonal meshes, i.e., polygonal meshes with singularities, which occur very frequently in the real-world. Most efficient polygonal compression methods currently available are restricted to a manifold mesh: they require converting a non-manifold mesh to a manifold mesh, and fail to retrieve the original model connectivity after decompression. The present method works by converting the original model to a manifold model, encoding the manifold model using an existing mesh compression technique, and clustering, or stitching together during the decompression process vertices that were duplicated earlier to faithfully recover the original connectivity. This paper focuses on efficiently encoding and decoding the stitching information. Using a naive method, the stitching information would incur a prohibitive cost, while our methods guarantee a worst case cost of O ( log m) bits per vertex replication, where m is the number of non-manifold vertices. Furthermore, when exploiting the adjacency between vertex replications, many replications can be encoded with an insignificant cost. By interleaving the connectivity, stitching information, geometry and properties, we can avoid encoding repeated vertices (and properties bound to vertices) multiple times; thus a reduction of the size of the bit-stream of about 10% is obtained compared with encoding the model as a manifold.

51 citations


Journal ArticleDOI
TL;DR: A robust color image retrieval algorithm based on the hybrid graph representation, i.e., a dual graph which consists of the Modified Color Adjacency Graph (MCAG) and Spatial Variance Graph (SVG), which yields high retrieval performance with tolerable computational complexity is proposed.

50 citations


Book ChapterDOI
TL;DR: Efficient polygon amalgamation methods by excluding those internal polygons without retrieving them from the database are investigated, and two novel algorithms, adjacency-based and occupancy-based, are proposed.
Abstract: The polygon amalgamation operation computes the boundary of the union of a set of polygons. This is an important operation for spatial on-line analytical processing and spatial data mining, where polygons representing different spatial objects often need to be amalgamated by varying criteria when the user wants to aggregate or reclassify these objects. The processing cost of this operation can be very high for a large number of polygons. Based on the observation that not all polygons to be amalgamated contribute to the boundary, we investigate in this paper efficient polygon amalgamation methods by excluding those internal polygons without retrieving them from the database. Two novel algorithms, adjacency-based and occupancy-based, are proposed. While both algorithms can reduce the amalgamation cost significantly, the occupancy-based algorithm is particularly attractive because: 1) it retrieves a smaller amount of data than the adjacency-based algorithm; 2) it is based on a simple extension to a commonly used spatial indexing mechanism; and 3) it can handle fuzzy amalgamation.

50 citations


Journal ArticleDOI
TL;DR: This paper considers constraint networks whose nodes are regular regions and whose constraints have the following forms: the eight “base relations” of [12], which describe binary topological relations of containment and adjacency between regions; and shows an important expressivity result for this language.
Abstract: This paper studies the expressivity and computational complexity of networks of constraints of topological relations together with convexity. We consider constraint networks whose nodes are regular regions (a regular region is one equal to the closure of its interior) and whose constraints have the following forms: (i) the eight ’’base relations‘‘ of [12], which describe binary topological relations of containment and adjacency between regions; (ii) the predicate, ’’ X is convex.‘‘ We establish tight bounds on the computational complexity of this language: Determining whether such a constraint network is consistent is decidable, but essentially as hard as determining whether a set of comparable size of algebraic constraints over the real numbers is consistent. We also show an important expressivity result for this language: If r and s are bounded, regular regions that are not related by an affine transformation, then they can be distinguished by a constraint network. That is, there is a constraint network and a particular node in that network such that there is a solution where the node is equal to r, but no solution where the node is equal to s.

48 citations


Journal ArticleDOI
TL;DR: The concept of pseudo-distance-regularity was introduced in this paper, which is based on giving each vertex u ∈ V a weight which equals the corresponding entry ν u of ν and regularizes the graph.

47 citations


Book ChapterDOI
11 Aug 1999
TL;DR: A linear space data structure for maintaining graphs with bounded arboricity--a large class of sparse graphs containing e.g. planar graphs and graphs of bounded treewidth--under edge insertions, edge deletions, and adjacency queries is presented.
Abstract: We present a linear space data structure for maintaining graphs with bounded arboricity—a large class of sparse graphs containing e.g. planar graphs and graphs of bounded treewidth—under edge insertions, edge deletions, and adjacency queries.

Journal ArticleDOI
TL;DR: Results suggest that timber adjacency costs are not overly sensitive to alternative strategies for management unit design that emphasize the generation of specific spa...
Abstract: Spatial considerations in ecosystem management are addressed within the framework of the forest management scheduling adjacency problem. Emphasis is on both the effectiveness of adjacency regulations and the consequences of strategies for management unit design. Four strategies are presented that subdivide stands into maximum-sized harvest units. A dynamic-programming heuristic is used to plan harvest schedules that comply with adjacency constraints over temporal horizons extending up to eight 10-year periods. The impact of stand design and adjacency constraints upon the output of the forest management problem is assessed. Specifically, timber revenues and spatial conditions generated by combining adjacency constraints with alternative strategies are analyzed. Results from test computer runs are discussed for applications in nine scenarios. Results suggest that timber adjacency costs are not overly sensitive to alternative strategies for management unit design that emphasize the generation of specific spa...

Patent
Alison Lennon1
15 Sep 1999
TL;DR: In this article, a method of classifying a digital image is disclosed, which provides a region adjacency graph ( 310 ) representing the digital image and analyses the graph for predetermined patterns.
Abstract: A method of classifying a digital image is disclosed. The method provides a region adjacency graph ( 310 ) representing the digital image and analyses the region adjacency graph ( 310 ) for predetermined patterns. For each identified pattern a classification of the digital image is selected. The region adjacency graph ( 310 ) is classified as one of a number of stereotypes.

Journal ArticleDOI
TL;DR: This paper presents a proof of the equivalence of two digital surface definitions based on simple surface points given by Morgenthaler and Rosenfeld and uses a parallel-move concept as given by direct adjacency.

Book ChapterDOI
15 Sep 1999
TL;DR: A new algorithm, called Nuage, for drawing graphs with both adjacency and inclusion relationships between nodes, that is, compound graphs, which is more general than classical graph models or clustered graphs is presented.
Abstract: We present a new algorithm, called Nuage, for drawing graphs with both adjacency and inclusion relationships between nodes, that is, compound graphs. Compound graphs are more general than classical graph models or clustered graphs. Nuage can be applied to both directed and undirected compound graphs. It can be parameterized by classical graph drawing algorithms. Nuage can be viewed as a method for unifying several classical algorithms within the same drawing by using the structure of the compound graph. Additionally, we present a refinement technique that can be used in conjunction with Nuage to reduce the number of edge crossings.


Proceedings ArticleDOI
01 Jan 1999
TL;DR: An automatic tracking system is presented which uses the matching of attributed region adjacency graphs to track moving objects through colour segmentation within a novel 2½ dimensional colour space drawing on established Hough transform techniques.
Abstract: An automatic tracking system is presented which uses the matching of attributed region adjacency graphs to track moving objects. The problem of object recognition with complex colour images is always made difficult by the changing shape and illumination of objects moving relative to complex light sources. Moreover, a moving camera causes additional complications in distinguishing an object. However, by identifying the colour regions of an object in one frame and looking for these regions in the next frame, object tracking can be achieved. This colour segmentation is efficiently performed within a novel 2½ dimensional colour space drawing on established Hough transform techniques. Automatic visual control of the motion tracking camera demands real-time processing of video streams.

Book ChapterDOI
17 Mar 1999
TL;DR: This paper proposes a model for digital topology based on the notion of order and discrete topology and "validates" this model by considering the two fundamental notions of surface and simple point.
Abstract: In the framework known as digital topology, two different adjacency relations are used for structuring the discrete space Zn.In this paper, we propose a model for digital topology based on the notion of order and discrete topology. We "validate" our model by considering the two fundamental notions of surface and simple point. At last, we give the different possible configurations that may appear in 2-and 3- dimensional surfaces in Z4 which correspond to our model.

Proceedings ArticleDOI
23 Jun 1999
TL;DR: A new approach for segmentation of nuclei observed with an epi-fluorescence microscope is presented and uses local feature activities such as step-edge segments, roof- edge segments, and concave corners to construct a set of initial hypotheses.
Abstract: A new approach for segmentation of nuclei observed with an epi-fluorescence microscope is presented. The technique is model based and uses local feature activities such as step-edge segments, roof-edge segments, and concave corners to construct a set of initial hypotheses. These local feature activities are extracted using either local or global operators to form a possible set of hypotheses. Each hypothesis is expressed as a hyperquadric for better stability, compactness, and error handling. The search space is expressed as an assignment matrix with an appropriate cost function to ensure local adjacency, and global consistency. Each possible configuration of a set of nuclei defines a path, and the path with the least error corresponds to best representation. This result is then presented to an operator who verifies and eliminates a small number of errors.

Journal ArticleDOI
TL;DR: The characteristic polynomial for its line graph, which has the bonds of a molecular graph as its beads with adjacency of bonds as in the graph, makes it possible to provide the general equation for calculating the radius of gyration of Gaussian chains and their relaxation spectra.
Abstract: We present a new graph‐theoretical method for calculating the dynamical and statistical properties of a Gaussian chain with various molecular architecture. The characteristic polynomial for its line graph, which has the bonds of a molecular graph as its beads with adjacency of bonds as in the graph, makes it possible to provide us with the general equation for calculating the radius of gyration of Gaussian chains and their relaxation spectra.

Book ChapterDOI
01 Jan 1999
TL;DR: A new algorithm for identifying objects in cluttered images, based on approximate subgraph matching, that is robust under moderate variations in the camera viewpoints and somewhat insensitive to minor graph variations is introduced.
Abstract: We introduce a new algorithm for identifying objects in cluttered images, based on approximate subgraph matching. This algorithm is robust under moderate variations in the camera viewpoints. In other words, it is expected to recognize an object (whose model is derived from a template image) in a search image, even when the cameras of the template and search images are substantially different. The algorithm represents the objects in the template and search images by weighted adjacency graphs. Then the problem of recognizing the template object in the search image is reduced to the problem of approximately matching the template graph as a subgraph of the search image graph. The matching procedure is somewhat insensitive to minor graph variations, thus leading to a recognition algorithm which is robust with respect to camera variations.

Journal ArticleDOI
29 Nov 1999
TL;DR: In this article, it was shown that the two conditions p: I, -+ I, is a surjection and W preserves adjacency are sufficient to characterize the basic group.
Abstract: In the space Ir of invariant r-dimensional subspaces of a null system in (2r + l)-dimensional projective space, W.L. Chow characterized the basic group of transformations as all the bijections : I, -+ Ir, for which both W and -1 preserve adjacency. In the present paper we show that the two conditions p: I, -+ I, is a surjection and W preserves adjacency are sufficient to characterize the basic group. At the end of this paper we give an application to Lie geometry.

Journal ArticleDOI
TL;DR: In this article, a new class of cyclic hypergraphs called Xrings are introduced, and a polynomial time algorithm is presented for deciding, given XringH1 and arbitrary hypergraphH2, whether there exists a tree projection of H2 with respect to H1.

Book ChapterDOI
15 Oct 1999
TL;DR: This chapter examines the way syntactic features are dealt with by interface systems and outlines a way of conceptualizing syntactic feature checking that treats checking and the locality configurations involved in checking as ways of rendering LF uninterpretable features acceptable to the Conceptual-Intentional interface.
Abstract: This chapter examines the way syntactic features are dealt with by interface systems. The core proposal is that the syntax morphology and syntax semantics interfaces both invoke feature interpretability but that the configurations in which they do so are different: the LF interface interprets syntactic features that are in spec-head or head-adjoined relations, whereas the interface with morphology, interprets syntactic features in adjacency relations. The chapter first outlines a way of conceptualizing syntactic feature checking that treats checking and the locality configurations involved in checking as ways of rendering LF uninterpretable features acceptable to the Conceptual-Intentional interface. It shows how that same conception of feature checking can be applied to morphologically (un)interpretable features, and proposes that a relevant configuration here is one of adjacency. Discussing the problem posed by subjects in VSO structures, the chapter outlines a number of analytical and theoretical problems with McCloskey's analysis. Keywords: adjacency; Conceptual-Intentional interface; LF uninterpretable features; McCloskey's analysis; morphology; VSO clause structure

Journal ArticleDOI
TL;DR: The proposed back-propagation neural network classifier is in a cascaded structure and has advantages that each network can be limited to a small size and trained independently.

Book ChapterDOI
17 Mar 1999
TL;DR: This paper deals with topological operators which achieve directly on the graph current operations performed on segmented images and shows how the topological coherence is maintained.
Abstract: The Topological Graph of Frontiers is in our opinion a good graph structure representing the topology of segmented images In this paper we deal with topological operators which achieve directly on the graph current operations performed on segmented images Well known graph structures such as the Region Adjacency Graph [Pav77] [Ros74] do not (and cannot) keep track of the topology and so cannot maintain it We claim that the structures and operators described here, on the contrary, allow and do this maintenance One of the most important informations in such images is the inclusion of nested regions and one of the most important operators is the union of regions We deal essentially with these in this paper They are described in detail herein and we show how the topological coherence is maintained This is why we entitle them topological operators Other operators that we have already developed are briefly described

Journal ArticleDOI
TL;DR: A parallel algorithm for testing the isomorphism of maximal outerplanar graphs, given the ordered adjacency lists of the two graphs, for graphs withNnodes on an EREW shared memory model, as well as on a hypercube arhitecture.

Journal ArticleDOI
TL;DR: In this article, the problem of a restricted random walk on graphs, which keeps track of the number of immediate reversal steps, is considered by using a transfer matrix formulation, and a closed-form expression is obtained for the generating function of the n-step walks with r reversal steps for walks on any graph.
Abstract: The problem of a restricted random walk on graphs, which keeps track of the number of immediate reversal steps, is considered by using a transfer matrix formulation. A closed-form expression is obtained for the generating function of the number ofn-step walks withr reversal steps for walks on any graph. In the case of graphs of a uniform valence, we show that our result has a probabilistic meaning, and deduce explicit expressions for the generating function in terms of the eigenvalues of the adjacency matrix. Applications to periodic lattices and the complete graph are given.

Journal ArticleDOI
TL;DR: Vizing's adjacency lemma is extended to multigraphs and it is shown that if xy is an edge then x is adjacent with at least Δ −deg( y)+1 vertices (≠ y ) of degree Δ .

01 Jan 1999
TL;DR: Benjamini, Lyons, Peres and Schramm as discussed by the authors showed that any automorphism invariant probability measure on f0; 1gn whose marginal probability that an edge is present is at least 2=(n + 1), produces in nite clusters with positive probability.
Abstract: In bond percolation on an in nite locally nite graph G = (V;E), each edge is randomly assigned value 0 (absent) or 1 (present) according to some probability measure on f0; 1g One then studies connectivity properties of the random subgraph of G which arises by removing each edge with value 0 Maximal connected components of that subgraph are called clusters, and of particular interest is the possible existence of in nite clusters Here we focus on the case where G is the regular tree Tn of order n 2 That is, Tn is the (unique) in nite connected graph that has no circuits and in which there are exactly n+ 1 edges emanating from each vertex We write En and Vn for the edge and vertex sets of Tn The most studied choice of probability measure on f0; 1g is iid measure When G = Tn, this reduces to the study of Galton{Watson branching processes with binomial o spring distribution Here we consider the more general class of automorphism invariant probability measures on f0; 1gn, ie measures that are invariant under graph automorphisms of Tn; a graph automorphism for Tn is a bijection : Vn ! Vn that preserves adjacency, together with the induced mapping 0 : En ! En There are several interesting examples (besides iid measure) of such probability measures, including the random-cluster model and uniform spanning forests; see eg Haggstrom (1996, 1997, 1998) In Haggstrom (1997), we showed that any automorphism invariant probability measure on f0; 1gn whose marginal probability that an edge is present is at least 2=(n + 1), produces in nite clusters with positive probability (this bound was also shown to be sharp) The proof involved a mass-transport argument, which was extended and exploited with great success by Benjamini, Lyons, Peres and Schramm (1998a) The mass-transport method is discussed in Section 2 Several results concerning the number and topological structure of in nite clusters were also given in Haggstrom (1997) For space reasons, some of the proofs were omitted in the nal version of that paper In Section 3 we shall recall these results and give new proofs, which are short and simple, based on the mass-transport method