a graduated assignment algorithm for graph matching a graduated assignment algorithm for graph matching is presented which is fast and accurate even in the presence of high noise by combining graduated nonconvexity two way assignment constraints and sparsity large improvements in accuracy and speed are achieved its low order computational complexity o lm where l and m are the number of links in the two graphs and robustness in the presence of noise offer advantages over traditional combinatorial approaches the algorithm not restricted to any special class of graph is applied to subgraph isomorphism weighted graph matching and attributed relational graph matching to illustrate the performance of the algorithm attributed relational graphs derived from objects are matched then results from twenty five thousand experiments conducted on 100 mode random graphs of varying types graphs with only zero one links weighted graphs and graphs with node attributes and multiple link types are reported no comparable results have been reported by any other graph matching algorithm before in the research literature twenty five hundred control experiments are conducted using a relaxation labeling algorithm and large improvements in accuracy are demonstrated

comparison of numerical methods for the calculation of two dimensional turbulence the estimate derived by henshaw kreiss and reyna for the smallest scale present in solutions of the two dimensional incompressible navier stokes equations is employed to obtain convergent pseudospectral approximations these solutions are then compared with those obtained by a number of commonly used numerical methods if the viscosity term is deleted and the energy in high wave numbers removed by setting the amplitudes of all wave numbers above a certain point in the spectrum to zero the chopped solution differs considerably from the convergent solution even at early times in the case that the regular viscosity is replaced by a hyperviscosity term i e the square of the laplacian we also derive an estimate for the smallest scale present if the coefficient of hyperviscosity is chosen so that the spectrum of the hyperviscosity solution disappears at the same point as for the regular viscosity solution the hyperviscosity solution is also completely different from the convergent solution if we tune the hyperviscosity coefficient then the solutions are similar in amplitude or phase but not both the solution obtained by a second order difference method with twice the number of points as the pseudospectral model or a fourth order difference method with the same number of points as the pseudospectral model is essentially identical to the convergent solution this is reasonable since most of the energy of the solution is contained in the lower part of the spectrum

constraint satisfaction problem with bilevel constraint application to interpretation of over segmented images abstract in classical finite domain constraint satisfaction problems the assumption made is that only one value is associated with only one variable for example in pattern recognition one variable is associated with only one segmented region however in practice regions are often oversegmented which results in failure of any one to one mapping this paper proposes a definition of finite domain constraint satisfaction problems with bilevel constraints in order to take into account a many to one relation between the values and the variables the additional level of constraint concerns the data assigned to the same complex variable then we give a definition of the arc consistency problem for bilevel constraint satisfaction checking a new algorithm for arc consistency to deal with these problems is presented as well this extension of the arc consistency algorithm retains its good properties and has a time complexity in o en 3 d 2 in the worst case this algorithm was tested on medical images these tests demonstrate its reliability in correctly identifying the segmented regions even when the image is over segmented

weight functions and fundamental fields for the penny shaped and the half plane crack in three space abstract weight functions permit to represent stress intensity factors as weighted averages of the externally impressed boundary tractions and body forces in this paper the relevant weight functions of all three modes are represented in closed form with the aid of elementary transcendentals their derivation as displacements of fundamental fields is simple and without recourse to integral transforms of any kind

error correcting graph matching on the influence of the underlying cost function investigates the influence of the cost function on the optimal match between two graphs it is shown that for a given cost function there are an infinite number of other cost functions that lead for any given pair of graphs to the same optimal error correcting matching furthermore it is shown that well known concepts from graph theory such as graph isomorphism subgraph isomorphism and maximum common subgraph are special cases of optimal error correcting graph matching under particular cost functions

length scale of interaction in spatiotemporal chaos extensive systems have no long scale correlations and behave as a sum of their parts various techniques are introduced to determine a characteristic length scale of interaction beyond which spatiotemporal chaos is extensive in reaction diffusion networks information about network size boundary condition or abnormalities in network topology gets scrambled in spatiotemporal chaos and the attenuation of information provides such characteristic length scales space time information flow associated with the recovery of spatiotemporal chaos from finite perturbations a concept somewhat opposite to the paradigm of lyapunov exponents defines another characteristic length scale high precision computational studies of asymptotic spatiotemporal chaos in the complex ginzburg landau system and transient spatiotemporal chaos in the gray scott network show that these different length scales are comparable and thus suitable to define a length scale of interaction preliminary studies demonstrate the relevance of these length scales for stable chaos

asymptotics of three dimensional macrocrack microcrack interaction abstract the perturbation in the mode i stress intensity factor along the edge of a half plane crack due to the opening of one or more co planar penny shaped cracks close to the edge calculated recently by the authors int j solids structures 30 2117 2139 1993 using the finite element method is shown to have the same logarithmic asymptotic behaviour as that of its plane strain two dimensional counterpart the approximate method of solution used in that paper however does not predict this asymptotic behaviour

three dimensional interactions of a half plane crack with point forces dipoles and moments abstract closed form solutions in terms of elementary functions are derived for stress intensity factors along the edge of a half plane crack induced by point forces dipoles centers of expansion and moments locations and orientations of these stress sources are arbitrary the solid is assumed to be either transversely isotropic with the crack parallel to the plane of isotropy or isotropic

graph matching with a dual step em algorithm this paper describes a new approach to matching geometric structure in 2d point sets the novel feature is to unify the tasks of estimating transformation geometry and identifying point correspondence matches unification is realized by constructing a mixture model over the bipartite graph representing the correspondence match and by affecting optimization using the em algorithm according to our em framework the probabilities of structural correspondence gate contributions to the expected likelihood function used to estimate maximum likelihood transformation parameters these gating probabilities measure the consistency of the matched neighborhoods in the graphs the recovery of transformational geometry and hard correspondence matches are interleaved and are realized by applying coupled update operations to the expected log likelihood function we evaluate the technique on two real world problems

complex ginzburg landau equation in the presence of walls and corners we investigate the influence of walls and corners with dirichlet and neumann boundary conditions in the evolution of two dimensional autooscillating fields described by the complex ginzburg landau equation analytical solutions are found and arguments provided to show that dirichlet walls introduce strong selection mechanisms for the wave pattern corners between walls provide additional synchronization mechanisms and associated selection criteria the numerical results fit well with the theoretical predictions in the parameter range studied

three dimensional elastic crack tip interactions with shear transformation strains abstract three dimensional elastic interactions between a half plane crack and sources of internal stress such as unconstrained shear transformation strains are analysed using bueckner s recent weight function method of three dimensional crack analysis analytical expressions arc given for the stress intensity factors induced along the crack front by unconstrained shear transformation strains for several simple shapes of the transformation domain centred at the origin when the centre of the transformation domain is not coincident with the origin of coordinates analytical expressions are too cumbersome to be of much practical value in such instances numerical results are presented for transformation domains in the shape of a sphere and an oblate spheroid the influence of the orientation of the latter is also studied

3d shape retrieval using kernels on extended reeb graphs abstract 3d shape retrieval is becoming an acute issue for numerous applications that span from cad to serious games to biomedicine and all contexts where it is fundamental to automatically retrieve geometric information from a collection of 3d models this paper addresses 3d shape retrieval in terms of a graph based description and the definition of a corresponding similarity measure for this purpose 3d models are represented as bags of shortest paths defined over well chosen extended reeb graphs while the similarity between pairs of extended reeb graphs is addressed through kernels adapted to these descriptions results are comparable with the best results of the literature and the modularity and evolutivity of the method ensure its applicability to other problems from partial shape matching to classification

symbolic graph matching with the em algorithm abstract this paper describes how relational graph matching can be effected using the expectation and maximisation algorithm according to this viewpoint matching is realised as a two step iterative em like process firstly updated symbolic matches are located so as to minimise the divergence between the model and data graphs secondly with the updated matches to hand probabilities describing the affinity between nodes in the model and data graphs may be computed the probability distributions underpinning this study are computed using a simple model of uniform matching errors as a result the expected likelihood function is defined over a family of exponential distributions of hamming distance we evaluate our matching method and offer comparison with both mean field annealing and quadratic assignment

matching delaunay graphs this paper describes a bayesian framework for matching delaunay triangulations relational structures of this sort are ubiquitous in intermediate level computer vision being used to represent both voronoi tessellations of the image plane and volumetric surface data our matching process is realised in terms of probabilistic relaxation the novelty of our method stems from its use of a support function specified in terms of face units of the graphs under match in this way we draw on more expressive constraints than is possible at the level of edge units alone in order to apply this new relaxation process to the matching of realistic imagery requires a model of the compatibility between faces of the data and model graphs we present a particularly simple compatibility model that is entirely devoid of free parameters it requires only knowledge of the numbers of nodes edges and faces in the model graph the resulting matching scheme is evaluated on radar images and compared with its edge based counterpart we establish the operational limits and noise sensitivity on the matching of random dot patterns

secondary structures in a one dimensional complex ginzburg landau equation with homogeneous boundary conditions experiments in extended systems such as the counter rotating couette taylor flow or the taylor dean flow system have shown that patterns with vanishing amplitude may exhibit periodic spatio temporal defects for some range of control parameters these observations could not be interpreted by the complex ginzburg landau equation cgle with periodic boundary conditions we have investigated the one dimensional cgle with homogeneous boundary conditions we found that in the benjamin feir stable region the basic wave train bifurcates to state with periodic spatio temporal defects the numerical results match the observations quite well we have built a new state diagram in the parameter plane spanned by the criticality or equivalently the linear group velocity and the nonlinear frequency detuning

near duplicate document image matching a graphical perspective a near duplicate document image matching approach characterized by a graphical perspective is proposed in this paper document images are represented by graphs whose nodes correspond to the objects in the images consequently the image matching problem is then converted to graph matching to deal with the instability of object segmentation a multi granularity object tree is constructed for a document image each level in the tree corresponds to one possible object segmentation while different levels are characterized by various object granularities some graphs can be generated from the tree and the objects associated with each graph may be of different granularities two graphs with the maximum similarity are found from the multi granularity object trees of the two near duplicate document images which are to be matched the encouraging experimental results have demonstrated the effectiveness of the proposed approach

interaction of penny shaped cracks with a half plane crack abstract three dimensional interactions between a half plane crack and penny shaped cracks which are not necessarily located in the same plane are analysed using the weight function method of three dimensional crack analysis analytical expressions are given for the interaction kernels in the integral equations with the opening displacements of penny shaped cracks as unknown functions by using the rayleigh ritz method the singularities of the kernels are weakened to make them suitable for finite element calculations the weak form equations are also solved by a simple method after approximating the opening displacement over each crack by a constant times a square root function of the distance from its edge this simple method of solution is shown to give results which are in excellent agreement with those of laures and kachanov 1991 int j fract 48 255 279

inexact graph matching by means of estimation of distribution algorithms abstract estimation of distribution algorithms edas are a quite recent topic in optimization techniques they combine two technical disciplines of soft computing methodologies probabilistic reasoning and evolutionary computing several algorithms and approaches have already been proposed by different authors but up to now there are very few papers showing their potential and comparing them to other evolutionary computational methods and algorithms such as genetic algorithms gas this paper focuses on the problem of inexact graph matching which is np hard and requires techniques to find an approximate acceptable solution this problem arises when a nonbijective correspondence is searched between two graphs a typical instance of this problem corresponds to the case where graphs are used for structural pattern recognition in images eda algorithms are well suited for this type of problems this paper proposes to use eda algorithms as a new approach for inexact graph matching also two adaptations of the eda approach to problems with constraints are described as two techniques to control the generation of individuals and the performance of edas for inexact graph matching is compared with the one of gas

inexact graph matching for model based recognition evaluation and comparison of optimization algorithms a method for segmentation and recognition of image structures based on graph homomorphisms is presented in this paper it is a model based recognition method where the input image is over segmented and the obtained regions are represented by an attributed relational graph arg this graph is then matched against a model graph thus accomplishing the model based recognition task this type of problem calls for inexact graph matching through a homomorphism between the graphs since no bijective correspondence can be expected because of the over segmentation of the image with respect to the model the search for the best homomorphism is carried out by optimizing an objective function based on similarities between object and relational attributes defined on the graphs the following optimization procedures are compared and discussed deterministic tree search for which new algorithms are detailed genetic algorithms and estimation of distribution algorithms in order to assess the performance of these algorithms using real data experimental results on supervised classification of facial features using face images from public databases are presented

interactive image segmentation by matching attributed relational graphs a model based graph matching approach is proposed for interactive image segmentation it starts from an over segmentation of the input image exploiting color and spatial information among regions to propagate the labels from the regions marked by the user provided seeds to the entire image the region merging procedure is performed by matching two graphs the input graph representing the entire image and the model graph representing only the marked regions the optimization is based on discrete search using deformed graphs to efficiently evaluate the spatial information note that by using a model based approach different interactive segmentation problems can be tackled binary and multi label segmentation of single images as well as of multiple similar images successful results for all these cases are presented in addition to a comparison between our binary segmentation results and those obtained with state of the art approaches an implementation is available at http structuralsegm sourceforge net

deterministic search for relational graph matching abstract this paper describes a comparative study of various deterministic discrete search strategies for graph matching the framework for our study is provided by the bayesian consistency measure recently reported by wilson and hancock ieee pami 19 1997 634 648 pattern recognition 17 1996 263 276 and wilson et al comput vision image understanding 72 1998 20 38 we investigate two classes of update process the first of these aims to exploit discrete gradient ascent methods we investigate the effect of searching in the direction of both the local and global gradient maximum an experimental study demonstrates that although more computationally intensive the global gradient method offers significant performance advantages in terms of accuracy of match our second search strategy is based on tabu search in order to develop this method we introduce memory into the search procedure by defining context dependant search paths we illustrate that although it is more efficient than the global gradient method tabu search delivers almost comparable performance

solution of lambda omega systems theta schemes and multigrid methods the numerical solution of a time dependent reaction diffusion lambda omega system discretized by theta schemes and finite differences is considered stability and accuracy of finite difference theta schemes for this system are established to solve the time implicit evolution equations a nonlinear multigrid method is applied the convergence properties of this solver are investigated considering a linearized lambda omega model

fuzzy morphisms between graphs a generic definition of fuzzy morphism between graphs gfm is introduced that includes classical graph related problem definitions as sub cases such as graph and subgraph isomorphism the gfm uses a pair of fuzzy relations one on the vertices and one on the edges each relation is a mapping between the elements of two graphs these two fuzzy relations are linked with constraints derived from the graph structure and the notion of association graph the theory extends the properties of fuzzy relation to the problem of generic graph correspondence we introduce two complementary interpretations of gfm from which we derive several interesting properties the first interpretation is the generalization of the notion of association compatibility the second is the new notion of edge morphism one immediate application is the introduction of several composition laws each property has a theoretical and a practical interpretation in the problem of graph correspondence that is explained throughout the paper special attention is paid to the formulation of a non algorithmical theory in order to propose a first step towards a unified theoretic framework for graph morphisms