Abstract
In this paper, we study the complexity of a data mining algorithm for extracting patterns from user web navigation data that was proposed in previous work.(3) The user web navigation sessions are inferred from log data and modeled as a Markov chain. The chain's higher probability trails correspond to the preferred trails on the web site. The algorithm implements a depth-first search that scans the Markov chain for the high probability trails. We show that the average behaviour of the algorithm is linear time in the number of web pages accessed.

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Abstract
Video encoding standards, namely MPEG-2, store large amounts of information obtained for compression purposes that can be accessed with minimal decoding. This paper shows that, with proper filtering of motion vectors and DCT coefficients, accurate segmentation results can be achieved by combining both reliable motion estimation and background subtraction. We further present a fine segmentation step that exploits specific blob characteristics to reduce segmentation noise and solve some occlusion problems. Examples using real videos from underground station CCTV cameras show that compressed domain information can be the key for successful surveillance applications where very fast algorithms with high accuracy are required.

Abstract
In this paper a set of specific applications under development for the Portuguese Shoe Industry are presented. The applications include CAD/CAM, the visualisation of graphical information (related to shoe and shoe components models) and the management of production and prototyping information. Besides describing some of the R&D details of the applications developed by the authors, this paper aims to present a case study of a successful technological application. It is part of a more general process for the introduction, in this industrial sector, of new production, management and administrative working philosophies, which are based on the centralisation of information and integrated global solutions. Copyright © 2004 by the Association for Computing Machinery, Inc.

Abstract
Relatively simple transformations can speed up the execution of queries for data mining considerably. While some ILP systems use such transformations, relatively little is known about them or how they relate to each other. This paper describes a number of such transformations. Not all of them are novel, but there have been no studies comparing their efficacy. The main contributions of the paper are: (a) it clarifies the relationship between the transformations; (b) it contains an empirical study of what can be gained by applying the transformations; and (c) it provides some guidance on the kinds of problems that are likely to benefit from the transformations.

Abstract
This work presents a hybrid maneuver for gradient search with multiple AUV's. The mission consists in following a gradient field in order to locate the source of a hydrothermal vent or underwater freshwater source. The formation gradient search exploits the environment structuring by the phenomena to be studied. The ingredients for coordination are the payload data collected by each vehicle and their knowledge of the behaviour of other vehicles and detected formation distortions. Copyright © 2004 IFAC. Copyright © 2004 IFAC