Topological and Directional Logo Layout Indexing

To evaluate similarity between two images, the layout or configuration of the shapes is an important feature besides geometrical shape similarity. In particular, trademark im- age retrieval is an application domain where layout sim- ilarity is important, and in many cases overlooked. In this paper, we present a graph-based encoding of layout, in which both directional and topological layout informa- tion is stored. A Hermitian matrix is associated to each graph, and contains all the information that is

present in the graph. The spectra of these Hermitian matrices are used for indexing purposes. By obeying several constraints on the construction of the Hermitian matrices, we can mimic the spectral behaviour of Laplacian matrices, which are proven to be successful representations in retrieval environments. Experiments show the improved representational power of the proposed approach over spectral methods using Lapla- cian matrices. KEY WORDS Indexing, image retrieval, trademarks, Laplacian, Hermi- tian, spectra 1. Introduction The key function of any indexing algorithm is to speed up content-based retrieval of objects or models that are stored in a database, by selecting a small set of candidate ob- jects that are either presented to the user, or passed on to a more refined matching unit in the retrieval pipeline. At this matching level, more accurate and more expensive match- ing algorithms can be deployed because of the reduced size of the set of objects that is under inspection. At the in- dexing level however, comparison of objects should be ef- ficient and it must be possible to prune the database, i.e. the database must be partitioned in such a way that simi- lar models are positioned close to each other. Only then objects that are far from the query object can be discarded without further inspection. Naturally, the representation of the objects in the in- dex and the accuracy and efficiency with which non-similar objects can be discarded are closely related. The objects that are under investigation in this work are logo and trade- mark images, or any kind of image in general where the layout of the individual image components (as opposed to their shape characteristics) is important for similarity eval- uation [10]. In content-based trademark image retrieval, layout can play a large role in identifying trademark in- fringement. See for an example Figure 1, where the con- figuration of the individual shapes is one of the most impor- tant properties. Suppose that in all three cases the five cir- cles are returned as a result of image segmentation (which would be the ideal segmentation), it is impossible to distin- guish between the images without any notion of layout in the representation. In this case, indexing algorithms (with- out layout information) will be less efficient because the set of candidate models will be unnecessary large. More importantly, indexing algorithms can be less accurate by ignoring layout. See Figure 2 for an illustration...

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The Flag-based Algorithm - International Journal of Computers

Proteins and the networks they determine, called interactome net- works, have received attention at an important degree during the last years, because they have been discovered to have an influence on some complex bi- ological phenomena, such as problematic disorders like cancer. This paper presents a contribution that aims to optimize the detection of protein commu- nities

through a greedy algorithm that is implemented in the C programming language. The optimization involves a double improvement in relation to pro- tein communities detection, which is accomplished both at the algorithmic and programming level. The resulting implementation’s performance was carefully tested on real biological data and the results acknowledge the relevant speedup that the optimization determines. Moreover, the results are in line with the previous findings that our current research produced, as it reveals and confirms the existence of some important properties of those proteins that participate in the carcinogenesis process. Apart from being particularly useful for research purposes, the novel community detection algorithm also dramatically speeds up the proteomic databases analysis process, as compared to some other se- quential community detection approaches, and also to the sequential algorithm of Newman and Girvan. Keywords: Interactome networks, protein-protein interactions, protein com- munities, cancer, greedy algorithm. 1 Introduction 1.1 Basic Considerations on Protein Networks and Their Importance Interactome networks, or, more specifically, networks of proteins, determine a fundamen- tal biological theoretical entity. Theoretical and practical endeavours often use interactome networks-related formalisms in order to analyze the protein interactions that determine a biolog- ical network, which is essential for the proper organization and function of a biological organism. These networks exhibit a complex structure, which implies that any research activity in the field is handled with inherent theoretical and technical difficulties. Nevertheless, the dynamics and the structure of these biological networks have to be accurately understood, as they play an important role on the function of a biological organism seen as a whole, regardless their degree of structural complexity. As a consequence, it is highly required to design and implement efficient proteomic data analysis techniques that can be integrated in any research framework that study the structure and properties of the interactome networks. Copyright c© 2006-2011 by CCC Publications 34 R. Bocu, S. Tabirca The aim of this paper is to present a novel and faster algorithm that performs the detection of communities in the interactome networks, based on a computationally-effective greedy technique. The significant influence that proteins exercise on fundamental physiological processes has been demonstrated in a series of recent contributions. In this respect, this paper re-states our research’s previous developments, apart from the algorithmic optimization itself, that cancer affects the most important proteins in the interactome network and, as a consequence, the normal function of the organism is greatly disturbed....

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Tuning Fuzzy Logic Controllers by Genetic Algorithms

The performance of a fuzzy logic controller depends on its control rules and membership functions. Hence, it is very important to adjust these parameters to the process to be controlled. A method is presented for tuning fuzzy control rules by genetic algorithms to make the fuzzy logic control systems behave as closely as possible to the operator or expert behavior in a control process. The tuning method fits the membership functions of the fuzzy rules given by the experts with the inference system and the defuzzification strategy selected, obtaining high-performance membership

functions by minimizing an error function defined using a set of evaluation input-output data. Experimental results show the method's good performance. KEYWORDS: fuz~ logic control systems, tuning, genetic algorithms 1. INTRODUCTION Recently fuzzy control techniques have been applied to many industrial processes. Fuzzy logic controllers (FLCs) are rule-based systems which are useful in the context of complex ill-defined processes, especially those which can be controlled by a skilled human operator without knowledge of their underlying dynamics. The essential part of the FLC system is a set of fuzzy control rules (FCRs) related by means of a fuzzy implication and the compositional rule of inference. Address correspondence to Francisco Herrera, Dept. of Computer Science and A.L, ETS de Ingenieda Inform6tica, University of Granada, 18071 Granada, Spain. *This research has been supported under project PB92-0933 Received July 1993; accepted November 1994. International Journal of Approximate Reasoning 1995; 12:299-315 © 1995 Elsevier Science Inc. 0888-613X/95/$9.50 655 Avenue of the Americas, New York, NY 10010 SSDI 0888-613X(94)00033-Y 300 F. Herrera, M. Lozano, and J. L. Verdegay FCRs are usually formulated in linguistic terms, in the form of IF-THEN rules, and there are different modes for deriving them [1]. In all cases, the correct choice of the membership functions of the linguistic label set plays an essential role in the performance of an FLC, it being difficult to represent the experts' knowledge perfectly by linguistic control rules. The fuzzy-control-rule base has many parameters, and its control de- pends on the tuning of the control system. Therefore, an FLC contains a number of sets of parameters that can be altered to modify the controller performance. They are [2]: • the scaling factors for each variable, • the fuzzy set representing the meaning of linguistic values, • the IF-THE N rules. Each of these sets of parameters have been used as controller parameters to be adapted in different adaptive FLCs. In this paper we present an adaptive FLC that modifies the fuzzy set definitions (it alters the shapes of the fuzzy sets defining the meaning of linguistic values) to determine the membership functions that produce maximum FLC performance according to the inference system (fuzzy implication and compositional operator) and the defuzzification strategies used--that is, to tune the FCR so as to make the FLC behave as closely as possible to the operator or expert behavior. This method relies on having a set of training data against...

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Drawing Graphs to Speed Up Shortest-Path Computations

We consider the problem of (repeatedly) computing single- source single-target shortest paths in large, sparse graphs. Previous investigations have shown the practical usefulness of geometric speed-up techniques that guarantee the correctness of the result for shortest-path computations. However, such speed-up techniques utilize a layout of the graph which typically comes from geographic information. This paper examines the question how geometric speed-up techniques can be used in case there is no layout given. We present an extensive computational study analyzing the usefulness of methods from graph drawing as foundation for such techniques. It turns out that using appropriate layout algorithms, a significant speed-up

can be achieved. 1 Introduction Single-source single-target shortest-path computation is a fundamental algorithmic problem with manifold applications. Especially, the computation of shortest- path queries in large graphs is a common task in many application scenarios. We are particularly interested in a situation where the graph is fairly large, but sparse and an expensive preprocessing is feasible. This typically arises in routing systems where a central server operates on a static graph that is too large to admit storage of shortest paths between all pairs of vertices. Without any preprocessing, Dijkstra’s algorithm [5] is the fastest known algorithm for the general case of arbitrary non-negative edge lengths, taking O(m + nlog n) worst-case time. In [16, 24, 25, 11] however, it has been shown that a considerable speed-up for the query time can be obtained for graphs with a given layout by using the according geometric information. The aim of this paper is to examine, if these techniques can be also utilized in the absence of a given layout. Applying methods from graph drawing, layouts are ⁄This work was partially supported by the Human Potential Programme of the European Union under contract no. HPRN- CT-1999-00104 (AMORE), by the European Commission - Fet Open project COSIN - COevolution and Self-organisation In dynamical Networks - IST-2001-33555, and by the EU within the 6th Framework Programme under contract 001907 (integated project DELIS). yUniversit˜at Karlsruhe, Fakult˜at f˜ur Informatik, Institut f˜ur Logik, Komplexit˜at und Deduktionssysteme, D-76128 Karlsruhe generated and used as foundation for geometric speed- up techniques. In [4], a related question has been studied for the special case of a timetable information system. A scenario is considered where the geographic information typically contained in timetable data is incomplete. Our results are more general with respect to the graphs considered, as well as the layout algorithms explored. We experiment with real world graphs from difierent areas and with various generated graphs. In particular, in contrast to [4] no additional information is used that might support the layout algorithms (like movement of trains or coordinates of selected stations). The main contribution of this paper consists in a computational study demonstrating that artiflcially produced layouts can indeed be used as basis for geometric speed-up techniques for shortest-path computations. For several of the graphs explored, signiflcant speed-ups are achieved with appropriately generated layouts. Moreover surprisingly, for many of the tested instances where layouts based on geographic informa-...

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SDE: Graph Drawing Using Spectral Distance Embedding

We present a novel algorithm for drawing undirected connected graphs, by using a spectral decomposition of the distance matrix to approximate the graph theoretical distances. The main advantages of our algorithm are that it is ”exact” (as opposed to iterative), and it gives results that preserve symmetry and uniform node density, i.e., the drawings are aesthetically pleasing. Our approach has the benefits of fast spectral techniques, but at the same time it produces drawings of a quality comparable to or better than the much slower force-directed approaches. The

computational complexity of our algorithm is governed by its two main steps: distance matrix computation using an all-pairs short- est path algorithm, which is O(|V||E|); and low-order spectral decomposition, which is O(|V|2). The runtime for typical 20,000 node graphs ranges from 100 to 150 seconds. 1 Introduction A graph G = (V,E) is a pair where V is the vertex set and E is the edge set, which is a binary relation over V . The graph drawing problem is to compute an aesthetically pleasing layout of vertices and edges so that it is easy to grasp visually the inherent structure of the graph. Depending on the aesthetic criteria of interest, various approaches have been developed, and a general survey can be found in [11,16]. We consider only the straight-line edge drawings of graphs, which reduces the problem to finding the coordinates of the vertices in two dimensions. A popular approach is to define an energy function or a force-directed model with respect to vertex positions, and to iteratively compute a local minimum of the energy function. The positions of the vertices at the local minimum produce the final layout. This approach is generally simple and easy to extend to new energy functions. Various energy functions and force models have been studied [4–6, 10] and there exist several improvements to handle large graphs, most of them concentrating on a multi-scale paradigm. This involves laying out a coarser level of the graph first, and then taking advantage of this coarse layout to compute the vertex positions at a finer level (eg. [15,18]). Spectral graph drawing approaches have become popular recently. We use the term spectral graph drawing to refer to any approachthat produces a final layout using the spectral decomposition of some matrix derived from the vertex and edge sets. In this paper, we present a spectral graph drawing algorithm, SDE (Spectral Distance Embedding), in which we use the spectral decomposition of the graph theoretical distance matrix to produce the final layout of the vertices. In the final layout, the pair-wise Euclidean distances of the vertices approximate the graph theoretical distances. SDE consists of two main steps: (i) all-pairs shortest path computation, which takes O(|V||E|) time. (ii) spectral decomposition of the distance matrix, in which we find the optimal rank-d reconstruction to embed in d-dimensions. The complexity of this step is O(d|V|2). SDE can be used to produce a d-dimensional...

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Spectral Sequencing Based on Graph Distance

The construction of linear mesh layouts has found various applications, such as implicit mesh filtering and mesh streaming, where a variety of layout quality criteria, e.g., span and width, can be considered. While spectral sequencing, derived from the Fiedler vector, is one of the best-known heuristics for minimizing width, it does not perform as well as the Cuthill-Mckee (CM) scheme in terms of span. In this paper, we treat optimal mesh layout generation as a problem of preserving graph distances and propose to use the subdominant eigenvector of a

kernel (affinity) matrix for sequencing. Despite the non-sparsity of the affinity operators we use, the layouts can be computed efficiently for large meshes through subsampling and eigenvector extrapolation. Our experiments show that the new sequences obtained outperform those derived from the Fiedler vector, in terms of spans, and those obtained from CM, in terms of widths and other important quality criteria. Therefore, in applications where several such quality criteria can influence algorithm performance simultaneously, e.g., mesh streaming and implicit mesh filtering, the new mesh layouts could potentially provide a better trade-off. 1 Introduction Computing linear mesh layouts is an instance of the graph layout problem [1], where an optimal labeling of the vertices of a given graph is sought. Many op- timization problems, including sparse matrix reordering [2–4], circuit layout [5], DNA sequencing [6], and ranking [7] , are formulated as graph layout problems. Consider a weighted graph G = (V,E,w) with V = {v1,...,vn} the set of vertices, E the set of edges, and w : E → R the edge weights. A (lin- ear) layout of G is a labeling pi of its vertices, pi : V → {1,2,...,n}. For a real number 0 < p < ∞, the p-discrepancy [7] of G with respect to a lay- out pi is defined as σp(G,pi) = ¡Puv∈E wuv|pi(u)−pi(v)|p¢1/p . If p = ∞, then σ∞(G,pi) = maxuv∈E |pi(v)−pi(v)|, and is also called the bandwidth of the layout. The minimum value σp(G) = minpi σp(G,pi),0 < p ≤∞, is called the min-p-sum of the graph G. Another important layout cost measure is vertex separation [1], defined as max1≤i≤n|{pi(u) ≤ i : ∃pi(v) > i,uv ∈ E}|. Intuitively, it measures, at a certain point of the linear layout, the number of edges for which only one 2 R. Liu, H. Zhang and O. van Kaick end vertex has been encountered. In the field of numerical analysis, various mea- sures, such as bandwidth [2], profile or envelope size [3] and workbound [4], are considered for sparse matrix reordering. It turns out that these measures are re- lated to different p-discrepancies of a graph layout, where the matrix of interest can be considered as the adjacency matrix of the graph G. Several problems in geometry processing [8,9] benefit from having an opti- mized mesh layout. A good example is mesh streaming [10], where the span and width, corresponding to bandwidth and vertex separation,...

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Dynamic Spectrum Access in DTV Whitespaces

This is an exciting development because DTV whites- paces are in the low frequency range (50-698 MHz) compared to typical cellular and ISM bands, thus resulting in much better propagation charac- teristics and much higher spectral efficiencies. The FCC has also mandated certain guidelines for short range unlicensed access, so as to avoid any in- terference to DTV receivers. We consider the problem of Wi-Fi like access (popularly referred to as Wi-Fi 2.0) for

enterprizes. We assume that the ac- cess points and client devices are equipped with cognitive radios, i.e., they can adaptively choose the center frequency, bandwidth and power of oper- ation. The access points can be equipped with one or more radios. In this paper, we layout the design of a complete system that (i) does not violate the FCC mandate, (ii) dynamically assigns center frequency and bandwidth to each access point based on their demands and (iii) squeezes the maximum efficiency from the available spectrum. This problem is far more general than prior work that investigated dynamic spectrum allocation in cellular and ISM bands, due to the non-homogeneous nature of the whitespaces, i.e., different whitespace widths in different parts of the spectrum and the large range of frequency bands with different propagation characteristics. This calls for a more holistic approach to system design that also accounts for frequency dependent propagation characteristics and radio frontend char- acteristics. In this paper, we first propose design rules for holistic system design. We then describe an architecture derived from our design rules. Finally we propose demand based dynamic spectrum allocation algorithms with provable worst case guarantees. We provide simulation results show- ing that (i) the performance of our algorithm is within 94% of the optimal in typical settings and (ii) and the DTV whitespaces can provide signifi- cantly higher data rates compared to the 2.4GHz ISM band. Our approach is general enough for designing any system with access to a wide range of spectrum. CategoriesandSubjectDescriptors: C.2.0 [General]: Data Com- munications; C.2.1 [Computer Communication Networks]: Net- work Architecture and Design-Wireless communication General Terms: Design, Algorithms 1. INTRODUCTION Across the world, countries are migrating from analog to digital television broadcasts. For example, in the US, this transition hap- pened on June 12, 2009; while in the UK, this transition is slated to happen in a phased manner from 2008 to 2012. In analog trans- Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. MobiCom’09, September 20–25, 2009, Beijing, China. Copyright 2009 ACM 978-1-60558-702-8/09/09 ...$10.00....

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