A Variational Framework for Structure from Motion in Omnidirectional Image Sequences We address the problem of depth and ego-motion estimation from omnidirectional images. We propose a correspondence-free structure-from-motion problem for sequences of images mapped on the 2-sphere. A novel graphbased variational framework is first proposed for depth estimation between pairs of images. The estimation is cast as a TV-L1 optimization problem that is solved by a fast graphbased algorithm. The ego-motion is then estimated directly from the depth information without explicit computation of the optical flow. Both problems are finally addressed together in an iterative algorithm that alternates between depth and ego-motion estimation for fast computation of 3D information from motion in image sequences. Experimental results demonstrate the effective performance of the proposed algorithm for 3D reconstruction from synthetic and natural omnidirectional images. Recently, omnidirectional imagers such as catadioptric cameras, have sparked tremendous interest in image processing and computer vision. These sensors are particularly attractive due to their (nearly) full field of view. The visual information coming from a sequence of omnidirectional images can be used to perform a 3D reconstruction of a scene. This type of problem is usually referred to as Structure from Motion (SFM) [9] in the literature. Let us imagine a monocular observer that moves in a rigid unknown world; the SFM problem consists in estimating the 3D rigid self-motion parameters, i.e., rotation and direction of translation, and the structure of the scene, usually represented as a depth map with respect to the observer position. Structure from motion has attracted considerable attention in the research community over the years with applications such as autonomous navigation, mixed reality, or 3D video.. In this paper we introduce a novel structure from motion framework for omnidirectional image sequences. We first consider that the images can be mapped on the 2-sphere, which permits to unify various models of single effective viewpoint cameras. Then we propose a correspondencefree SFM algorithm that uses only differential motion between two consecutive frames of an image sequence through brightness derivatives. Since the estimation of a dense depth map is typically an ill-posed problem, we build on [3] and we propose a novel variational framework that solves the SFM problem on the 2-sphere when the camera motion is unknown. Variational techniques are among the most successful approaches to solve under-determined inverse prob-lems and efficient implementations have been proposed recently so that their use becomes appealing [26] . We show in this paper that it is possible to extend very efficient variational approaches to SFM problems, while naturally handling the geometry of omnidirectional images. We embed a discrete image in a weighted graph whose connections are given by the topology of the manifold and the geodesic distances between pixels. We then cast the depth estimation problem as a TV-L1 optimization problem, and we solve the resulting variational problem with fast graph-based optimization techniques similar to [10, 20, 27] . To the best of our knowledge, this is the first time that graph-based variational techniques are applied to obtain a dense depth map from omnidirectional image pairs.. Then we address the problem of ego-motion estimation from the depth information. The camera motion is not perfectly known in practice, but it can be estimated from the depth map. We propose to compute the parameters of the 3D camera motion with the help of a low-complexity least square estimation algorithm that determines the most likely motion between omnidirectional images using the depth information. Our formulation permits to avoid the explicit computation of the optical flow field and the use of feature matching algorithms. Finally, we combine both estimation procedures to solve the SFM problem in the generic situation where the camera motion is not known a priori. The proposed iterative algorithm alternatively estimates depth and camera ego-motion in a multi-resolution framework, providing an efficient solution to the SFM problem in omnidirectional image sequences. Experimental results with synthetic spherical images and natural images from a catadioptric sensor confirm the validity of our approach for 3D reconstruction.. The rest of the paper is structured as follows. We first provide a brief overview of the related work in Sect. 2. Then, we describe in Sect. 3 the framework used in this paper for motion and depth estimation and the corresponding discrete operators in graph-based representations. The variational depth estimation problem is presented in Sect. 4, and the egomotion estimation is discussed in Sect. 5. Section 6 presents the joint depth and ego-motion estimation algorithm, while Sect. 7 presents experiments of 3D reconstruction from synthetic and natural omnidirectional image sequences. We have presented in this paper a novel variational framework for solving the structure from motion problem in omnidirectional image sequences. We have developed a graphbased construction of discrete differential operators for the processing of images on the 2-sphere. These operators permit to develop an efficient algorithm for depth estimation that is robust to the geometrical characteristics of the spherical manifold. We have then proposed a simple algorithm that directly estimates the camera motion from the depth information. Finally, we provide an iterative algorithm for joint depth and ego-motion estimation. The proposed framework provides accurate geometry information for both synthetic and natural omnidirectional images. The efficiency and low complexity of the proposed algorithm positions it as a promising solution for fast depth estimation and scene reconstruction from omnidirectional image sequences. The depth and ego-motion estimation problems have been quite widely studied in the last couple of decades and we describe here the most relevant papers that present correspondence-free techniques. Correspondence-free algorithms get rid of feature computation and matching steps that might prove to be complex and sensitive to transformations between images. Most of the literature in correspondencefree depth estimation is dedicated to stereo depth estimation [22] . In the stereo depth estimation problem cameras are usually separated by a large distance in order to efficiently capture the geometry of the scene. Registration techniques are often used to find a disparity map between the two image views, and the disparity is eventually translated into a depth map. In our problem, we rather assume that the displacement between two consecutive frames in the sequence is small as it generally happens in image sequences. This permits to compute the differential motion between images and to build low-complexity depth estimation through image brightness derivatives. Then, most of the research about correspondence-free depth estimation has concentrated on perspective images; the depth estimation has also been studied in the case of omnidirectional images in [18] , which stays as one of the rare works that carefully considers the specific geometry of the images in the depth estimation. We handle this geometry by graph-based processing on a spherical manifold and we introduce a novel variational framework in our algorithm, which is expected to provide a high robustness to quantization errors, noise or illumination gradients.. On the other hand, ego-motion estimation approaches usually proceed by first estimating the image displacement field, the so-called optical flow. The optical flow field can be related to the global motion parameters by a mapping that depends on the specific imaging surface of the camera. The mapping typically defines the space of solutions for the motion parameters, and specific techniques can eventually be used to obtain an estimate of the ego-motion [6, 13, 16, 24] . Most techniques reveal sensitivity to noisy estimation of the optical flow. The optical flow estimation is a highly illposed inverse problem that needs some sort of regularization in order to obtain displacement fields that are physically meaningful; a common approach is to impose a smoothness constraint on the field [5, 14] . In order to avoid the computation of the optical flow, one can use the so-called "direct approach" where image derivatives are directly related to the motion parameters. Without any assumption on the scene, the search space of the ego-motion parameters is limited by the depth positivity constraint. For example, the works in [15, 23] estimate the motion parameters that result into the smallest amount of negative values in the depth map. Some algorithms originally proposed for planar cameras have later been adapted to cope with the geometrical distortion introduced by omnidirectional imaging systems. For example, an omnidirectional ego-motion algorithm has been presented by Gluckman in [11] , where the optical flow field is estimated in the catadioptric image plane and then back-projected onto a spherical surface. Not many, though, have been trying to take advantage from the wider field of view of the omnidirectional devices: in spherical images the focus of expansion and the focus of contraction are both present, which imply that translation motion cannot be confused with rotational one. In our work, we take advantage of the latter property and directly estimate the ego-motion with a very efficient scheme based on a least square optimization problem, which further permits to avoid the computation of the optical flow.. Ideas of alternating minimization steps have also been proposed in [1, 12] . In these works, however, the authors use planar sensors and assume to have an initial rough estimate of the depth map. In addition, they use a simple locally constant depth model. In our experiments we show that this model is an oversimplification of the real world, which does not apply to scenes with a complex structure. In the novel framework proposed in this paper, we use a spherical camera model and we derive a linear set of motion equations that explicitly include camera rotation. The complete egomotion parameters can then be efficiently estimated jointly with depth.

O B O O B I I O B O O O O O O O O O B O O B O O O O O O O O O O O O O O O O O O B O O O O O B I O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O B B I O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O B I I O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B I O O O O B O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O B I O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O B B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Robust camera pose estimation using 2d fiducials tracking for real-time augmented reality systems Augmented reality (AR) deals with the problem of dynamically and accurately align virtual objects with the real world. Among the used methods, vision-based techniques have advantages for AR applications, their registration can be very accurate, and there is no delay between the motion of real and virtual scenes. However, the downfall of these approaches is their high computational cost and lack of robustness. To address these shortcomings we propose a robust camera pose estimation method based on tracking calibrated fiducials in a known 3D environment, the camera location is dynamically computed by the Orthogonal Iteration Algorithm. Experimental results show the robustness and the effectiveness of our approach in the context of real-time AR tracking. AR systems attempt to enhance an operator's view of the real environment by adding virtual objects, such as text, 2D images, or 3D models, to the display in a realistic manner. It is clear that the sensation of realism felt by the operator in an augmented reality environment is directly related to the stability and the accuracy of the registration between the virtual and real world objects, if the virtual objects shift or jitter, the effectiveness of the augmentation is lost.. Several AR systems have been developed these last years, they can be subdivided into two categories: Vision-based AR systems (indirect vision) and see-through AR systems (direct vision). Vision-based techniques have more advantages for AR applications. First, the same video camera used to capture real scenes also serves as a tracking device. Second, the pose calculation is most accurate in the image plane, thereby minimizing the perceived image alignment error. Additionally, processing delays in the video and graphics subsystems can be In this paper we described a robust solution for vision based augmented reality tracking that identifies and tracks, in realtime, known 2D fiducials made up of corners, in order to estimate the camera pose. The major advantages of tracking corners are their detection robustness at a large range of distances, and their reliability under severe orientations. Additionally, we have adapted the orthogonal iteration algorithm to our problem and have demonstrate its efficiency in such applications. Figure 5 shows four frames of the video sequence showing virtual objects rendering. For each frame, the camera pose was estimated using two 2D detected fiducials. From figures (5-a), (5-b), (5-c) and (5-d) we can see that virtual objects are well superimposed on the real world. Our current implementation exhibits an average reprojection error between 0.7 and 1.2 pixels. , illustrates the robustness of our approach to: (c) Effects of rotations Effects of scales, the major advantage in using corners for tracking is that corners are invariant to scale. Figure (6-a) shows that our 2D fiducials tracker can detect and identify markers in spite of the large range of distances from the camera.

O B I I O O B I O O B I O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Selection of Concept Detectors for Video Search by Ontology-Enriched Semantic Spaces Abstract-This paper describes the construction and utilization of two novel semantic spaces, namely Ontology-enriched Semantic Space (OSS) and Ontology-enriched Orthogonal Semantic Space (OS 2 ), to facilitate the selection of concept detectors for video search. These two semantic spaces are enriched with ontology knowledge, while emphasizing consistent and uniform comparison of ontological relatedness among concepts for query-to-concept mapping. OS 2 , in addition to being a linear space like OSS, also guarantees orthogonality of the semantic space. Compared with other ontology reasoning measures, both spaces are capable of providing platforms that offer a global view of concept inter-relatedness, by allowing evaluation of concept similarity in metric spaces. We simulate OSS and OS 2 by using LSCOM concepts and experiment search effectiveness with VIREO-374 concept detectors. Empirical observations indicate that the proposed semantic spaces enable more effective selection of concept detectors than eight other existing ontology measures. OS 2 , in particular, is better in providing a viable and reasonable solution for fusion of multiple concept detectors.Index Terms-Semantic space, ontology, concept-based video search, semantic detectors. In the past few years, concept-based video retrieval has attracted numerous research attention. Two critical efforts are detection of semantic concepts and utilization of concepts as "semantic filters" for query answering. Since 2001, TRECVID (TREC Video Retrieval Evaluation) [11] sponsored by NIST has organized annual workshops to publicly release benchmarks and evaluations to support these efforts. Two tasks organized by TRECVID are high-level feature extraction (HLFE) and automatic video search. In HLFE, concept detectors are developed for video semantic annotation. In order to identify a right set of detectors to develop, collaborative efforts from various research organizations have been pooled in to assess the utility, observability and flexibility of the concept detectors [12] . One typical example is the release of LSCOM (Large-Scale Concept Ontology for Multimedia, http://www.lscom.org/) [12] which includes 834 semantic concepts and a collection of annotations (training examples) for 449 out of the 834 concepts. With LSCOM, two detector sets, Columbia-374 [13] and VIREO-374 [14] , are also publicly released to share the sets of detectors developed based on the concepts in LSCOM. Another detector set commonly used is MediaMill-101 [15] which provides 101 concept detectors.. With the availability of various concept detector sets, the automatic video search in TRECVID is often straightforward to perform based on the concept-based retrieval framework depicted in Fig. 1 . Various studies [2] - [4] , [16] have been reported regarding the usefulness of concepts for video search, compared to search with low-level features and text keywords. The completeness, accuracy and utility of LSCOM concepts towards effective search performance is also investigated in [17] . Recently, the fundamental question of how many detectors are enough for effective video search is studied in [18] . In this work, it is reported that fewer than 5000 concepts, detected with minimal accuracy of 10%, is likely to provide satisfactory retrieval performance.. In this section, we begin by briefly describing the existing concept similarity measures for ontology reasoning in Section II.A. The related works in ontology-based video search will be further presented in Section II.B. A brief comparison of anchor-based selection approaches to our proposed semantic spaces will also be discussed in Section II.C.

O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O B I O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O B B I I B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Regularized regression on image manifold for retrieval Recently, there have been considerable interests in geometric-based methods for image retrieval. These methods consider the image space as a smooth manifold and apply manifold learning techniques to find a Euclidean embedding. Thus, the Euclidean distances in the embedding space can be used as approximations to the geodesic distances on the manifold. A main advantage of these methods is that the relevance feedbacks during retrieval can be naturally incorporated into the system as prior information. In this paper, we consider the retrieval problem as a classification problem on manifold. Instead of learning a distance measure, we aim to learn a classification function on the image manifold. Considering efficiency is a key issue in image retrieval, especially on the Web scale, we propose a novel approach for image retrieval on manifold. This approach is based on a regularized linear regression framework. The local manifold structure and user-provided relevance feedbacks are incorporated into the image retrieval system through a Locality Preserving Regularizer. Extensive experiments are carried out on a large image database which demonstrates the efficiency and effectiveness of the proposed approach. Content-Based Image retrieval (CBIR) has been a long standing problem in multimedia. Unlike text-based search which has achieved enormous success, the state-of-the-art CBIR systems are still far from satisfactory [24] , [4] , [21] . The difficulty of CBIR is essentially due to the difficulty of representing an image. The components of a text document, i.e., terms, can faithfully describe the topics of the document; whereas the components of an image, i.e., pixels, can hardly describe any semantics of the image. Let us compare the space of text documents with that of images. The document space is usually linear or close to linear. That is, if we add two document vectors together, the new document vector can still describe the topics of the two original documents to some extent. However, if we add two image vectors (pixel wise) together, the resulting image is not a naturally generated image and can no longer describe the semantics of the original two images. Mathematically, this is because of the non-linearity and disconnectivity of the pixel-based space of natural images.. Instead of pixels, visual features like color, texture, and shape have been proposed to represent images. This is referred to as feature vector thereafter, and the space of feature vectors is referred to as feature space. Since visual features cannot always describe the semantics of the images, relevance feedback is introduced as a powerful tool for soliciting information from the users [23] . During the last decade, relevance feedback has been at the core of the CBIR research. Most of the previous research on relevance feedback has fallen into the following three categories: (1) retrieval based on query point movement [22] , (2) retrieval based on re-weighting of different feature dimensions [19] , and (3) retrieval based on updating the probability distribution of images in the database [7] . However, all of these methods fail to take into account the geometrical structure of the feature space.. Recently there have been considerable interests in geometrically motivated approaches for image retrieval [11] , [12] , [13] , [20] , [31] . These methods consider the image feature space as a nonlinear space, particularly, manifold. He et al. proposed a method that finds a Euclidean embedding of the image manifold and performs image retrieval in the embedding space [13] . Lin et al. proposed an Augmented Relation Embedding method that maps the feature space into a semantic manifold which grasps the user's preferences. They construct two feedback relational graphs to incorporate the user-provided positive and negative examples [20] . Moreover, a manifold ranking-based method has been proposed to explore the relationships among all the data points in the feature space, and measure the relevances between the query and all the images in the database accordingly, which is different from traditional similarity metrics based on pair-wise distance [11] . These methods can successfully discover the intrinsic image manifold structure. However, they aim to learn a distance measure on the image manifold, rather than a classification function on the image manifold. Therefore, they fail to make full use of the user-provided relevance feedbacks and thus may not be optimal in the sense of discriminating relevant images from irrelevant ones.. In this paper, we propose a novel approach for image retrieval on manifold. Our approach is fundamentally based on a regularized linear regression framework. There are many classification methods in literature, such as Support Vector Machine (SVM, [29] ), boosting [26] , Linear Discriminant Analysis (LDA, [8] ), and regression [10] . Previous work has demonstrated that SVM can significantly improve retrieval performance [28] [16] . However, one of the main disadvantages of SVM is its high computational complexity. It can hardly be scaled to the Web environment where the image search system needs to response to tens of thousands queries simultaneously. Therefore, we consider using the regression framework in this study. Besides its computational efficiency, another advantage of regression is that the prior information can be easily incorporated as a regularization term. Specifically, we first build an adjacency graph to model the local image manifold structure. User's relevance feedbacks are used to update the graph structure. In this way, the classifier obtained minimizes the least square error and simultaneously respects the graph structure.. The following highlights the major contributions of the paper:. 1. The problem of relevance feedback image retrieval is a typical small-sample learning problem. Therefore, when regression framework is considered, a key factor is how to regularize it. The traditional solution to this is to apply an L2 norm of the classification function which leads to minimum norm classifier, generally referred to as ridge regression. Such regularization term is data independent. The regularization term used in our approach explicitly takes into account the geometrical structure of the data space and makes use of the user's relevance feedbacks.. 2. Most of previous manifold-based image retrieval methods consider image retrieval as a distance-based ranking problem. They suffer from the problem of how to combine the user-provided positive and negative examples. Different from them, we consider the image retrieval problem as a classification problem on manifolds which allows us to make efficient use of relevance feedbacks.. The rest of this paper is organized as follows. In Section 2, we provide a brief review of regression. We introduce our image retrieval approach on manifold in Section 3. The experimental results are presented in Section 4. Finally, we conclude the paper and provide suggestions for future work in Section 5. A novel image retrieval approach on manifold is proposed in this paper. Our retrieval method is based on learning a classification function on the image manifold. Our method has two major advantages: as a classification based method, our method is more efficient than subspace learning based methods; second, our method explicitly takes into consideration the geometrical structure of the image manifold by making use of both labeled and unlabeled images. Several experiments demonstrate the efficiency and effectiveness of our method.. Due to the efficiency consideration, the algorithm proposed in our paper is linear. Thus it may fail to capture those complex image manifolds which are highly non-linear. However, it is easy to extend our algorithm to Reproducing Kernel Hilbert Space (RKHS) which leads to Locality Preserving Regularized Kernel Regression.. We have noticed that there is a trend in many areas, including multimedia information retrieval, computer vision, pattern recognition, and data mining, that the data points are considered as drawn from sampling a probability distribution that has support on or near a submanifold of Euclidean space. Manifold based techniques have shown its superiority to Euclidean based techniques for CBIR by several researchers [13] , [20] , [11] . All of these algorithms (including the one presented in this paper) have a implicit assumption that the data points are uniformly sampled from the image manifold. If the data points are not uniformly sampled from the manifold, the graph Laplacian may not converge to the true Laplace Beltrami operator on the manifold. However, the real world image database might be much more complicated and far from uniform. We are currently exploring this problem in theory and practice.

O B O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O O O B O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I B I O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


A Novel FPGA Architecture and an Integrated Framework of CAD Tools for Implementing Applications SUMMARY A complete system for the implementation of digital logic in a Field-Programmable Gate Array (FPGA) platform is introduced. The novel power-efficient FPGA architecture was designed and simulated in STM 0.18 µm CMOS technology. The detailed design and circuit characteristics of the Configurable Logic Block, the interconnection network, the switch box and the connection box were determined and evaluated in terms of energy, delay and area. A number of circuit-level low-power techniques were employed because power consumption was the primary concern. Additionally, a complete tool framework for the implementation of digital logic circuits in FPGA platforms is introduced. Having as input VHDL description of an application, the framework derives the reconfiguration bitstream of FPGA. The framework consists of: i) non-modified academic tools, ii) modified academic tools and iii) new tools. Furthermore, the framework can support a variety of FPGA architectures. Qualitative and quantitative comparisons with existing academic and commercial architectures and tools are provided, yielding promising results. FPGAs have recently benefited from technology process advances to become a significant alternative to Application Specific Integrated Circuits (ASICs). An important feature that has made FPGAs, particularly attractive is that the logic mapping and implementation flow is similar to the ASIC design flow (from VHDL or Verilog down to the configuration bitstream) provided by the industrial sector [1], [2] . However, in order to implement real-life applications on an FPGA platform, embedded or discrete, increasingly performance and power-efficient FPGA architectures are required. Furthermore, efficient architectures cannot be used effectively without a complete set of tools for implementing logic while utilizing the advantages and features of the target device.. Consequently, research has lately focused on the development of FPGA architectures [3]- [6] , [8] , [9] , [33] . Also, many solid efforts for the development of a complete tool design flow from the academic sector have also taken place [6] , [9] , [10] . The above design groups have focused on the development of tools that can target a variety of FPGA architectures, while keeping the tools open-source. Despite the above efforts, there is a gap in the complete design flow (from VHDL to configuration bit-stream) provided by existing academic tools. This is mainly due to the lack of an open-source synthesizer and a FPGA configuration bit-stream generation tool. Therefore, there is no existing complete academic system capable of implementing logic specified in a hardware description language in a FPGA, just an assortment of various fine-grain architectures and tools that cannot be easily integrated into a complete system.. In this paper, such a complete system is introduced. The hardware design of an efficient FPGA architecture is presented. Exhaustive circuit-level exploration in terms of power, delay and area at both Configurable Logic Block (CLB) design and interconnection architecture has been applied in order to make appropriate architecture decisions. Particularly, Basic Logic Element (BLE) using gated clock approach is investigated, at CLB level, while at interconnect network level, new research results about the type and sizing of routing switches are presented in 0.18 µm STM process. This investigation is mostly focused on minimizing power dissipation, since it is our primary target in this FPGA implementation, without significantly degrading delay and area. Based on these results and for validation purposes, a full-custom 8 × 8 FPGA was realized in 0.18 µm CMOS STM technology.. Additionally, a complete toolset is introduced for mapping logic on the FPGA mentioned above is presented, starting from a VHDL circuit description down to the FPGA configuration bitstream. To best of our knowledge, the developed framework is the only one complete design flow in academia and supports a variety of FPGA architectures. Furthermore, it consists: i) non-modified academic tools, ii) modified academic tools and iii) new tools. The FPGA architecture and tools were developed as part of the AMDREL project [11] and the tools can be run on-line at the AMDREL website [11] .. The rest of the paper is organized as follows: Section 2 describes the FPGA hardware platform in detail, while Sect. 3 is a brief presentation of the tools. Section 4 provides a number of quantitative and qualitative comparisons with existing academic and commercial approaches to evaluate the entire system of tools and platform. Conclusions are further discussed in Sect. 5. A novel FPGA architecture (CLB, interconnect and configuration architecture) with low-power features was presented together with complete tool framework for implementing logic in this platform. The proposed system of the FPGA (implemented in 0.18 µm STM technology) and tool framework showed promising results when compared with commercial products using a number of benchmarks.

O O B O O O O O O B I O O O O O O O O O O O O O O O O O O B O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O B O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B B I O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O


Discovering Simulation Models Abstract. Process mining is a tool to extract non-trivial and useful information from process execution logs. These so-called event logs (also called audit trails, or transaction logs) are the starting point for various discovery and analysis techniques that help to gain insight into certain characteristics of the process. In this paper we use a combination of process mining techniques to discover multiple perspectives (namely, the control-flow, data, performance, and resource perspective) of the process from historic data, and we integrate them into a comprehensive simulation model. This simulation model is represented as a Coloured Petri net (CPN) and can be used to analyze the process, e.g., evaluate the performance of different alternative designs. The discovery of simulation models is explained using a running example. Moreover, the approach has been applied in two case studies; the workflows in two different municipalities in the Netherlands have been analyzed using a combination of process mining and simulation. Furthermore, the quality of the CPN models generated for the running example and the two case studies has been evaluated by comparing the original logs with the logs of the generated models. Computer simulation is a useful and versatile tool to gain insight into the operation of systems. Next to, e.g., natural systems also human systems can be subject to simulation. Generally, a model that represents certain key characteristics or behaviors of the system is analyzed to show the eventual real effects of alternative conditions and courses of action. The strength of simulation is that it enables precisely this "what if" analysis, i.e., it allows to "look into the future" under certain assumptions. In this paper, we focus on simulation models of operational processes. For example, in the context of a workflow management system simulation can help to estimate the benefit of an anticipated process redesign, or to predict flow times for an increasing number of incoming cases, a reduced number of specialists for a certain task etc.. Traditionally, such simulation models are created manually (cf. Figure 1 ). Documentation, interviews and close observation help to get an understanding of the real-world process of interest. This is a time-consuming activity, which is likely to be error-prone as it is based on human perception of reality rather than on reality itself. Good knowledge of the observed operational process is inevitable for drawing conclusions from a simulation run. Therefore, we propose to use process mining techniques to (semi-)automatically discover a simulation model based on information that was recorded during process enactment. This way, we can much quicker arrive at a first simulation model (to be further evaluated and potentially modified) than with the traditional approach. In addition, it is likely to better represent reality as it is based on objective information. This paper demonstrates that it is possible to automatically construct simulation models based on event logs. These simulation models need to cover different perspectives: control-flow, data, resources, time, etc. Therefore, we showed that each of these perspectives can be discovered using existing process mining techniques and that all these mining results can be merged into a single simulation model.. The approach has been implemented in the context of ProM and has been tested using different examples. In this paper, we used an artificial example and two case studies to evaluate our approach. Based on this we can conclude that it is indeed possible to automatically construct simulation models based on event logs. The discovered models can be exported to CPN Tools which allows for all kinds of simulation. Using the monitoring functionality of CPN it is possible to do all kinds of measurements and to feed the results back to ProM. In this paper, we did not focus on the analysis of the processes of the two municipalities (although extensive simulation studies have been done by students doing their final Master projects in these two municipalities). The reason is that it is obvious that good simulation models have a high practical value. Therefore, we focused on the validation of our approach.. Given the relevance of simulation and the problems people have making good simulation models, we will continue to work on the topics mentioned in this paper. We are exploring various ways to improve the various plug-ins mentioned. Moreover, we would like to improve the modeling of human behavior. Note that in the case studies people were only working part-time on the processes at hand. As a result, we had to add additional waiting time to the models based on an analysis of the log. However, this is not satisfactory since it does not really capture the way that people actually work. Other directions of future work are the automated support of redesign (i.e., suggesting process improvements based on log analysis and simulation of alternatives [15] ) and the use of simulation for real-time decision making (i.e., making recommendations for current cases based on a mixture of process mining and short-term simulation [17] ). work on process mining techniques. We would also like to thank Lisa Wells and Kurt Jensen for their support in using CPN Tools. The work reported in this paper is related to earlier work on process mining, i.e., discovering a process model based on some event log. The idea of applying process mining in the context of workflow management was first introduced in [5] . Cook and Wolf have investigated similar issues in the context of software engineering processes using different approaches [6] . Herbst and Karagiannis also address the issue of process mining in the context of workflow management using an inductive approach [10] . They use stochastic task graphs as an intermediate representation and generate a workflow model described in the ADONIS modeling language. The α algorithm [4, 24] was one of the first algorithms to truly capture concurrency. In [4] it is shown that this algorithm can be proven to be correct for a large class of processes. Over time many variants and extensions of the α algorithm have been proposed. In [24] a heuristic approach using rather simple metrics is used to construct so-called "dependency/frequency tables" and "dependency/frequency graphs". This is used as input for the α algorithm. As a result it is possible to tackle the problem of noise. For more information on process mining we refer to a special issue of Computers in Industry on process mining [3] and a survey paper [2] .. Existing process mining approaches have been mainly focusing on the controlflow perspective. Some initial work has been done for discovering social networks in the context of process mining [1] and decision point analysis [20] . However, these techniques do not provide an integrated view and do not aim at simulation. This paper is mostly related to [21] where the CPN export of ProM is described. However, the focus of [21] is not on process mining and no case studies are given.. There is quite some work on the automatic generation of Petri net models for workflows. A typical example is described in [8] where the authors present a translation of Protos simulation models to CPN Tools. In addition, three types of data collector monitors (measuring the total flow time per case, the waiting time per task, and the resource availability/utilization per resource type), and configuration features enabling the dynamic elimination of unnecessary parts of the process model are generated. Besides the work in [8] , we are not aware of further attempts to export business process models to CPN Tools. The work reported in this paper has a different starting point as it is not limited by the simulation information present in a Protos model, but aims at discovering the process characteristics to be simulated from the event logs of real process executions.

O B I O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Investigation of the global dynamics of cellular automata using Boolean derivatives Global dynamics of a non-linear Cellular Automaton (CA), is, in general irregular, asymmetric and unpredictable as opposed to that of a linear CA, which is highly systematic and tractable. In this paper, efforts have been made to systematize non-linear CA evolutions in the light of Boolean derivatives and Jacobian matrices. A few new theorems on Hamming Distance between Boolean functions as well as on Jacobian matrices of cellular automata are proposed and proved. Moreover, a classification of Boolean functions based on the nature of deviation from linearity has been suggested with a view to grouping them together to classes/subclasses such that the members of a class/subclass satisfy certain similar properties. Next, an error vector, which cannot be captured by the Jacobian matrix, is identified and systematically classified. This leads us to the concept of modified Jacobian matrix whereby a quasi-affine representation of a non-linear cellular automaton is introduced.

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B I O O O O O O O O O O O


A Logical Approach to Efficient Max-SAT solving Weighted Max-SAT is the optimization version of SAT and many important problems can be naturally encoded as such. Solving weighted Max-SAT is an important problem from both a theoretical and a practical point of view. In recent years, there has been considerable interest in finding efficient solving techniques. Most of this work focus on the computation of good quality lower bounds to be used within a branch and bound DPLL-like algorithm. Most often, these lower bounds are described in a procedural way. Because of that, it is difficult to realize the logic that is behind.In this paper we introduce an original framework for Max-SAT that stresses the parallelism with classical SAT. Then, we extend the two basic SAT solving techniques: search and inference. We show that many algorithmic tricks used in state-of-the-art Max-SAT solvers are easily expressable in logic terms with our framework in a unified manner.Besides, we introduce an original search algorithm that performs a restricted amount of weighted resolution at each visited node. We empirically compare our algorithm with a variety of solving alternatives on several benchmarks. Our experiments, which constitute to the best of our knowledge the most comprehensive Max-sat evaluation ever reported, show that our algorithm is generally orders of magnitude faster than any competitor.Key words: Max-SAT, search, inference ⋆ This paper includes and extends preliminary work from [1, 2] Weighted Max-SAT is the optimization version of the SAT problem and many important problems can be naturally expressed as such. They include academic problems such as max cut or max clique, as well as real problems in domains like routing [3] , bioinformatics [4] , scheduling [5] , probabilistic reasoning [6] , electronic markets [7] . In recent years, there has been a considerable effort in finding efficient exact algorithms. These works can be divided into theoretical [8, 9, 10] and empirical [11, 12, 13, 14] . A common drawback of all these algorithms is that albeit the close relationship between SAT and Max-SAT, they cannot be easily described with logic terminology. For instance, the contributions of [11, 12, 13, 14] are good quality lower bounds to be incorporated into a depth-first branch and bound procedure. These lower bounds are mostly defined in a procedural way and it is very difficult to see the logic that is behind the execution of the procedure. This is in contrast with SAT algorithms where the solving process can be easily decomposed into atomic logical steps.. In this paper we introduce an original framework for (weighted) Max-SAT in which the notions of upper and lower bound are incorporated into the problem definition. Under this framework classical SAT is just a particular case of Max-SAT, and the main SAT solving techniques can be naturally extended. In particular, we extend the basic simplification rules (for example, idempotency, absorption, unit clause reduction, etc) and introduce a new one, hardening, that does not make sense in the SAT context. We also extend the two fundamental SAT algorithms: DPLL (based on search) and DP (based on inference). We also show that the complexity of the extension of DP is exponential on the formula's induced width (which is hardly a surprise, since this is also the case of other inference algorithms for graphical models [15, 16] ). Interestingly, our resolution rule includes, as special cases, many techniques spread over the recent Max-SAT literature. One merit of our framework is that it allows to see all these techniques as inference rules that transform the problem into an equivalent simpler one, as it is customary in the SAT context.. The second contribution of this paper is more practical. We introduce an original search algorithm that incorporates three different forms of resolution at each visited node: neighborhood resolution, chain resolution and cycle resolution. Our experimental results on a variety of domains indicate that our algorithm is orders of magnitude faster than its competitors. This is especially true as the ratio between the number of clauses and the number of variables increases. Note that these are typically the hardest instances for Max-SAT. Our experiments include random weighted and unweighted Max-SAT instances, random and structured Max-one problems, random Max-cut problems, random and structured Max-clique problems and combinatorial auctions.. Some of the ideas presented in this paper have strong connections to different techniques recently developed in the WCSP field [17] . Especially significant is the connection with local consistency [18, 19, 20, 21, 22] and variable elimination [15, 23, 24] .. The structure of the paper is as follows: In Section 2 we review SAT terminology. In Section 3 we present Max-SAT and introduce our framework. In Section 4 we extend from SAT to Max-SAT the essential solving techniques. Section 5 summarizes in a unified way special forms of resolution that can be used to simplify Max-SAT formula. Section 6 describes our solver. Section 7 reports our experimental work, which corroborate the efficiency of our solver compared to other state-of-the-art solving alternatives. Finally, Section 8 concludes and points out directions of future work. This paper introduces a novel Max-SAT framework which highlights the relationship between SAT and Max-SAT solving techniques. Most remarkably, it extends the concept of resolution. Our resolution rule, first proposed in [1] , has been proved complete in [35] . There are many beneficial consequences of this approach:. • It allows to talk about Max-SAT solving with the usual SAT terminology.. • It allows to naturally extend basic algorithms such as DPLL and DP.. • It allows to express several solving techniques that are spread around the Max-SAT literature with a common formalism, see their logical interpretation and see the connection with similar SAT, CSP and WCSP techniques. From a practical point of view, we have proposed a hybrid algorithm that combines search and selected forms of inference. It follows a typical search strategy but, at each visited node, it attempts to simplify the current subproblem using special cases of resolution with which the problem is transform into a simpler, equivalent one. Our experiments on a variety of domains show that our algorithm is usually orders of magnitude faster than its competitors.. Our current solver lacks features that are considered very relevant in the SAT context (for example clause learning, re-starts, etc). Since our framework makes the connection between SAT and Max-SAT very obvious, they should be easily incorporated in the future. Additionally, some of the ideas presented in this paper have been borrowed from the weighted CSP field [17] . Therefore, it seems also possible to incorporate new (weighted) constraint processing techniques. Finally, we want to note the recent work of [41] in which very good lower bounds are obtained by temporarily setting ⊤ = 1 and simulating unit propagation. Since the hyper-resolution rules presented in Section 5.2 are special cases of their more general algorithm, we want to explore if their approach can be fully described with our resolution rule.

O O O O O B O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O B O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B B B O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Calculation of Shell Frequency Distributions Obtained with Shell-Mapping Schemes Abstract| In order to calculate the transmit power in shell{mapping{based transmission schemes, the frequencies of the shells are required. In this paper, a simple but general method for the calculation of these frequencies is derived. The method has approximately the same complexity as the shell{mapping encoder. As an example, the method is shown in detail for the shell{mapping scheme speci ed for the international telephone{line V.34 modem standard. Moreover, a very simple approximation is given which is tight for large constellations. In this paper, a simple but general method for the calculation of the frequencies of the shells in shell{mapping schemes was derived. As an example, the method was shown in detail for the shell{mapping scheme speci ed for the international telephone{line modem standard ITU Recommendation V.34. The method starts with partial histograms that give the number of occurrences of shells within all possible combinations of n{tuples of shells with some xed total cost. These histograms can be calculated easily using the generating functions that are needed in the encoder in any case. Then, the shell{mapping encoder is run with a speci c input, namely the maximum K{tuple. To each step of the encoding procedure a partial histogram can be assigned. Summing up these parts yields the nal histograms. Thus the calculation has approximately the same complexity as the mapping encoder itself. With the knowledge of the frequencies of shells, the exact average transmit power can be calculated. Numerical examples are given for V.34.

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O


Real world dynamic appearance enhancement with procam feedback : The contrast of a less saturated picture that exists in the real world is enhanced by our system. The left image is the appearance under the white light projection, the center image is enhanced result by the compensation light projection and the right image is compensation pattern that generated projector camera feedback. The enhancement is implemented by the dynamical feedback of projector camera system, and the system performed the enhancement with the processing speed of 11.4 fps under the fluorescent light condition.In this paper, a dynamic appearance enhancement method for the less saturated object is proposed. The appearance enhancement method proposed in this paper is realized with a projector camera dynamic feed back system. Therefore, the proposed method has an ability of the rapid and continuous appearance enhancement and it is useful for the human visual perception assistance. Also, the system not requires a pre-captured appearance of the target. In recent years, many adaptive projection systems that aim the photometric compensation for the non-uniformity surface color was proposed (e.g. [Grossberg et al. 2004; Fujii et al. 2005; Ashdown et al. 2006] ).However not only photometric compensation but also opposite technique that enhances the non-uniform appearance of object is useful for human visual perception assistance. For example, visual assistance for the color-blind person and industrial visual inspection, color rendering control for stage lighting etc. Recently, Bimber [Bimber and Iwai 2008] proposed the technique that improves the dynamic range of the object's appearance by the superimposing with the projector. However, the continuous adaptation was not shown. Therefore, for the mentioned applications, we * e-mail: amano@is.naist.jp † e-mail: kato@is.naist.jp adopt the dynamical projector camera feedback for the appearance enhancement that makes a point of rapid and continuous response to keep higher visibility without blinking for the visual perception assistance. In this paper, we proposed a appearance enhancement method by the projector camera feedback system. This enabled the enhancements of object's brightness and contrast in sequentially at the real world and its effectiveness was confirmed by experimental results of less saturated picture and faded picture. The remaining problems are the color compensation non-uniformity that caused lens aberration and improvement for the brightness contrast for the faded picture. We would like to solve these problems in a future work.

O O O B B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B B O O O O O O O O O B B O O O O O O O O O O O O O O O O O O O O O O O O O O O B B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B B O O O O O O O O O O O O O O O O O O O O O O O O O O B B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Mining Authoritativeness of Collaborative Innovation Partners The global marketplace over the past decade has called for innovative products and cost reduction. This perplexing duality has led companies to seek external collaborations to effectively deliver innovative products to market. External collaboration often leads to innovation at reduced research and development expenditure. This is especially true of companies which find the most authoritative entity (usually a company or even a person) to work with. Authoritativeness accelerates development and research-to-product transformation due to the inherent knowledge of the authoritative entity. This paper offers a novel approach to automatically determine the authoritativeness of entities for collaboration. This approach automatically discovers an authoritative entity in a domain of interest. The methodology presented utilizes web mining, text mining, and generation of an authoritativeness metric. The concepts discussed in the paper are illustrated with a case study of mining the authoritativeness of collaboration partners for microelectromechanical systems (MEMS). Innovation most often occurs in one of two forms, incremental or radical. Radical (discontinuous) innovation assumes focuses on a completely new concept that is radically different from the existing ideas. This type of innovation occurs rarely and is not easily predictable. Incremental, or continuous, innovation builds upon previous concepts and therefore it is easier to be quantified. Kusiak [1] defined innovation as an iterative process aimed at the creation of new products, processes, knowledge or services by the use of new or even existing technology. This definition summarizes the typology of incremental innovation.. Innovation has further been quantified into five generational models. The first generational model is linear, where innovation is unidirectionally pushed from the research phase to the commercial application phase [2] , [3] . The second model, the pull model, holds the consumer as the main focus of innovation as opposed to the designer [4] . Feedback forms the third model and utilizes the consumer's responses to an initial product/service offering to perform incremental innovation on that product and/or service [5] . The fourth model is known as the strategic model in which innovation lines up directly with the company's strategy [2] .. The model pursued in this paper is the fifth model, also known as the networked model. In this model extraenterprise and cross-discipline organizations form a network to innovate. The term Open Innovation [6] is often used when describing this model. Collaborative networking involves a detection of the optimal sources of collaboration. This can often be viewed as a challenge and often results in the local optimum as the choice of the collaborative source rather than the unseen, and most often unknown, global optima (e.g., the most authoritative person/company).. The success of collaborative innovation depends greatly on the quality of the collaboration sources. The probability of innovation success, as measured by the market, can be considered proportional to the quality of the collaborative sources. Therefore, it is incumbent upon a company, in pursuit of innovation, to seek out the optimal sources for collaboration. A wealth of information is available upon the World Wide Web (WWW) for identifying the optimal sources of collaboration (e.g., white-papers written by authorities of specific domains).. Various researchers have begun to investigate possible means by which collaboration produces effective results. Unfortunately, the literature is lacking solid systematic methodologies by which collaboration authoritativeness may be determined apriori of collaboration inception. Chapman et al. [22] proposed a process model for collaborative data mining in an electronic manner but fail to address the need for authoritativeness when determining the collaborative partner selection process. Lavraĉ et al. [23] surveyed various methodologies for collaboration but fail to report a systematic methodology of determining the most authoritative entity for collaboration. Gajda [24] investigated assessment measures for determining the success of a collaborative partnership on a project. Unfortunately, these measures are considered upon the completion of the project rather than to determine the effective partners for collaboration prior to entering in to a collaborative agreement.. Other researchers have posited criteria and methodologies for collaboration partner selection. Geringer [25] proposed task-related selection criteria for international joint ventures but failed to present a systematic methodology for automatically determining the authoritativeness of a collaborative partner. Hitt et al. [26] investigated resource-based and organizational learning for collaborative partner selection. Again, the methodologies in the literature fall short of the goal of automated systematic determination of authoritativeness for collaboration.. This paper presents machine learning algorithms to extract collaborative innovation relationship information from various sources including the WWW. Utilizing machine learning algorithms to discover valuable knowledge from disparate sources has been presented in the literature. Chen [27] posited utilizing natural computing techniques, such as swarm intelligence, to foster a collective intelligence in a virtual learning environment. Grebla et al. [28] presented a Bayesian belief network for mining data from various databases to assist in predicting arteriosclerosis and cardiovascular disease.. This paper offers a novel methodology by which the optimal authoritative sources of collaborative partnership may be discovered. Through the use of web mining, text mining, and the creation of an authoritativeness matrix, users may determine the optimal authority with which to perform collaborative innovation. Of course, optimality may depend upon more than just the most authoritative partner on a given subject. Other factors such as the availability of the collaborator or the cultural background of the collaborator (e.g., defense systems collaboration) may be involved. Thus, this paper advocates the creation of an authoritativeness matrix as opposed to simply defining global optima for collaboration.. The remainder of this paper proceeds as follows. Section 2 discusses the focused mining of the World Wide Web to discover authoritative sources for collaboration. The distillation of these sources to form an authoritativeness matrix is discussed in Section 3. An authoritativeness metric is presented in Section 4. Section 5 discusses clustering of the mined sources of collaboration. Section 6 offers a case study for determining the leading authorities on microelectromechanical systems (MEMS). Finally, Section 7 offers concluding remarks.

O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I B I O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


An efficient condition for a graph to be Hamiltonian Let G = (V , E) be a 2-connected simple graph and let d G (u, v) denote the distance between two vertices u, v in G. In this paper, it is proved: if the inequality

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Improving abstract interpretations by combining domains In this paper we consider static analyses based on ab-