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31
Path similarity skeleton graph matching
 IEEE TRANS. PAMI
, 2008
"... This paper proposes a novel graph matching algorithm and applies it to shape recognition based on object silhouettes. The main idea is to match skeleton graphs by comparing the geodesic paths between skeleton endpoints. In contrast to typical tree or graph matching methods, we do not consider the to ..."
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Cited by 53 (8 self)
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This paper proposes a novel graph matching algorithm and applies it to shape recognition based on object silhouettes. The main idea is to match skeleton graphs by comparing the geodesic paths between skeleton endpoints. In contrast to typical tree or graph matching methods, we do not consider the topological graph structure. Our approach is motivated by the fact that visually similar skeleton graphs may have completely different topological structures. The proposed comparison of geodesic paths between endpoints of skeleton graphs yields correct matching results in such cases. The skeletons are pruned by contour partitioning with Discrete Curve Evolution, which implies that the endpoints of skeleton branches correspond to visual parts of the objects. The experimental results demonstrate that our method is able to produce correct results in the presence of articulations, stretching, and contour deformations.
Differencing and Merging Architectural Views
 Automated Software Engineering Journal
"... As architecturebased techniques become more widely adopted, software architects face the problem of reconciling different versions of architectural models. However, existing approaches to differencing and merging architectural views are based on restrictive assumptions, such as requiring view eleme ..."
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Cited by 38 (15 self)
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As architecturebased techniques become more widely adopted, software architects face the problem of reconciling different versions of architectural models. However, existing approaches to differencing and merging architectural views are based on restrictive assumptions, such as requiring view elements to have unique identifiers or explicitly log changes between versions. To overcome some of the above limitations, we propose differencing and merging architectural views based on structural information. To that effect, we generalize a published polynomialtime treetotree correction algorithm (that detects inserts, renames and deletes) into a novel algorithm to additionally detect restricted moves and support forcing and preventing matches between view elements. We implement a set of tools to compare and merge componentandconnector (C&C) architectural views, incorporating the algorithm. Finally, we provide an empirical evaluation of the algorithm and the tools on case studies with real software, illustrating the practicality of the approach to find and reconcile interesting divergences between architectural views.
Static Extraction and Conformance Analysis of Hierarchical Runtime Architectural Structure
"... An object diagram makes explicit the object structures that are only implicit in a class diagram. An object diagram may be missing and must extracted from the code. Alternatively, an existing diagram may be inconsistent with the code, and must be analyzed for conformance with the implementation. One ..."
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Cited by 30 (23 self)
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An object diagram makes explicit the object structures that are only implicit in a class diagram. An object diagram may be missing and must extracted from the code. Alternatively, an existing diagram may be inconsistent with the code, and must be analyzed for conformance with the implementation. One can generalize the global object diagram of a system into a runtime architecture which abstracts objects into components, represents how those components interact, and can decompose a component into a nested subarchitecture. A static object diagram represents all objects and interobject relations possibly created, and is recovered by static analysis of a program. Existing analyses extract static object diagrams that are nonhierarchical, do not scale, and do not provide meaningful architectural abstraction. Indeed, architectural
Learning shapeclasses using a mixture of treeunions
 IEEE Trans. PAMI
, 2006
"... Abstract—This paper poses the problem of treeclustering as that of fitting a mixture of tree unions to a set of sample trees. The treeunions are structures from which the individual data samples belonging to a cluster can be obtained by edit operations. The distribution of observed tree nodes in ea ..."
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Cited by 27 (8 self)
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Abstract—This paper poses the problem of treeclustering as that of fitting a mixture of tree unions to a set of sample trees. The treeunions are structures from which the individual data samples belonging to a cluster can be obtained by edit operations. The distribution of observed tree nodes in each cluster sample is assumed to be governed by a Bernoulli distribution. The clustering method is designed to operate when the correspondences between nodes are unknown and must be inferred as part of the learning process. We adopt a minimum description length approach to the problem of fitting the mixture model to data. We make maximumlikelihood estimates of the Bernoulli parameters. The treeunions and the mixing proportions are sought so as to minimize the description length criterion. This is the sum of the negative logarithm of the Bernoulli distribution, and a messagelength criterion that encodes both the complexity of the uniontrees and the number of mixture components. We locate node correspondences by minimizing the edit distance with the current tree unions, and show that the edit distance is linked to the description length criterion. The method can be applied to both unweighted and weighted trees. We illustrate the utility of the resulting algorithm on the problem of classifying 2D shapes using a shock graph representation. Index Terms—Structural learning, tree clustering, mixture modelinq, minimum description length, model codes, shock graphs. 1
A Binary Linear Programming Formulation of the Graph Edit Distance
"... A binary linear programming formulation of the graph edit distance for unweighted, undirected graphs with vertex attributes is derived and applied to a graph recognition problem. A general formulation for editing graphs is used to derive a graph edit distance that is proven to be a metric provided t ..."
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Cited by 25 (3 self)
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A binary linear programming formulation of the graph edit distance for unweighted, undirected graphs with vertex attributes is derived and applied to a graph recognition problem. A general formulation for editing graphs is used to derive a graph edit distance that is proven to be a metric provided the cost function for individual edit operations is a metric. Then, a binary linear program is developed for computing this graph edit distance, and polynomial time methods for determining upper and lower bounds on the solution of the binary program are derived by applying solution methods for standard linear programming and the assignment problem. A recognition problem of comparing a sample input graph to a database of known prototype graphs in the context of a chemical information system is presented as an application of the new method. The costs associated with various edit operations are chosen by using a minimum normalized variance criterion applied to pairwise distances between nearest neighbors in the database of prototypes. The new metric is shown to perform quite well in comparison to existing metrics when applied to a database of chemical graphs.
Fast suboptimal algorithms for the computation of graph edit distance
 STRUCTURAL, SYNTACTIC, AND STATISTICAL PATTERN RECOGNITION. LNCS
, 2006
"... Graph edit distance is one of the most flexible mechanisms for errortolerant graph matching. Its key advantage is that edit distance is applicable to unconstrained attributed graphs and can be tailored to a wide variety of applications by means of specific edit cost functions. Its computational com ..."
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Cited by 18 (2 self)
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Graph edit distance is one of the most flexible mechanisms for errortolerant graph matching. Its key advantage is that edit distance is applicable to unconstrained attributed graphs and can be tailored to a wide variety of applications by means of specific edit cost functions. Its computational complexity, however, is exponential in the number of vertices, which means that edit distance is feasible for small graphs only. In this paper, we propose two simple, but effective modifications of a standard edit distance algorithm that allow us to suboptimally compute edit distance in a faster way. In experiments on real data, we demonstrate the resulting speedup and show that classification accuracy is mostly not affected. The suboptimality of our methods mainly results in larger interclass distances, while intraclass distances remain low, which makes the proposed methods very well applicable to distancebased graph classification.
RegionBased Hierarchical Image Matching
 INT J COMPUT VIS
, 2007
"... This paper presents an approach to regionbased hierarchical image matching, where, given two images, the goal is to identify the largest part in image 1 and its match in image 2 having the maximum similarity measure defined in terms of geometric and photometric properties of regions (e.g., area, b ..."
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Cited by 14 (6 self)
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This paper presents an approach to regionbased hierarchical image matching, where, given two images, the goal is to identify the largest part in image 1 and its match in image 2 having the maximum similarity measure defined in terms of geometric and photometric properties of regions (e.g., area, boundary shape, and color), as well as region topology (e.g., recursive embedding of regions). To this end, each image is represented by a tree of recursively embedded regions, obtained by a multiscale segmentation algorithm. This allows us to pose image matching as the tree matching problem. To overcome imaging noise, onetoone, manytoone, and manytomany node correspondences are allowed. The trees are first augmented with new nodes generated by merging adjacent sibling nodes, which produces directed acyclic graphs (DAGs). Then, transitive closures of the DAGs are constructed, and the tree matching problem reformulated as finding a bijection between the two transitive closures on DAGs, while preserving the connectivity and ancestordescendant relationships of the original trees. The proposed approach is validated on real images showing similar objects, captured under different types of noise, including differences in lighting conditions, scales, or viewpoints, amidst limited occlusion and clutter.
Layered Analysis of Irregular Facades via Symmetry Maximization
"... Figure 1: Symmetrydriven structural analysis of an irregular facade (a) results in a hierarchical decomposition (b) into regular grids. Our analysis introduces layering (b), going beyond flat segmentation via splits (c) and allowing more compact and natural structural representations. The resulting ..."
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Cited by 11 (2 self)
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Figure 1: Symmetrydriven structural analysis of an irregular facade (a) results in a hierarchical decomposition (b) into regular grids. Our analysis introduces layering (b), going beyond flat segmentation via splits (c) and allowing more compact and natural structural representations. The resulting hierarchical model of facades enables applications such as structural editing (d) and retargeting (e). We present an algorithm for hierarchical and layered analysis of irregular facades, seeking a highlevel understanding of facade structures. By introducing layering into the analysis, we no longer view a facade as a flat structure, but allow it to be structurally separated into depth layers, enabling more compact and natural interpretations of building facades. Computationally, we perform a symmetrydriven search for an optimal hierarchical decomposition defined by split and layering operations applied to an input facade. The objective is symmetry maximization, i.e., to maximize the sum of symmetry of the substructures resulting from recursive decomposition. To this end, we propose a novel integral symmetry measure, which behaves well at both ends of the symmetry spectrum by accounting for all partial symmetries in a discrete structure. Our analysis results in a structural representation, which can be utilized for structural editing and exploration of building facades. Links: DL PDF WEB VIDEO DATA CODE 1
Aggregation of composite solutions: strategies, models, examples. Electronic preprint
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Improving System Dependability by Enforcing Architectural Intent
 In: Proceedings of the Workshop on Architecting Dependable Systems
, 2005
"... Developing dependable software systems requires enforcing conformance between architecture and implementation during software development and evolution. We address this problem with a multipronged approach: (a) automated refinement of a componentandconnector (C&C) architectural view into an i ..."
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Cited by 8 (4 self)
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Developing dependable software systems requires enforcing conformance between architecture and implementation during software development and evolution. We address this problem with a multipronged approach: (a) automated refinement of a componentandconnector (C&C) architectural view into an initial implementation, (b) enforcement of architectural structure at the programming language level, (c) automated abstraction of a C&C view from an implementation, and (d) semiautomated incremental synchronization between the architectural and the implementation C&C views.