30089105
A fixed point theorem for o-minimal structures
We prove a definable analogue to Brouwer's Fixed Point Theorem for o-minimal structures of real closed field expansions: A continuous definable function mapping from the unit simplex into itself admits a fixed point, even though the underlying space is not necessarily topologically complete. Our proof is direct and elementary; it uses a triangulation technique for o-minimal functions, with an application of Sperner's Lemma. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
16497195
Computable Economic Analysis
This paper discusses an economic equilibrium theory with computabil-ity constraints on both the magnitudes (prices, quantities, etc.) and the operations (to perceive, evaluate, choose, communicate, etc) that agents can use. Prices and quantities are computable numbers (Turing (1936)), and preference relations, utility functions, demand functions are computable (in the sense of Moschovakis (1964)). We present sharper versions of several traditional assertions on utility representation , existence of consumer demand functions, the fundamental welfare theorems, characterizations of market excess demands. We also give a \computable coun-terexample" to the existence of a competitive equilibrium. These results can be interpreted as possibility and impossibility results in computability-bounded ratio-nality, and in computational economics.
35972713
Positioning Models for Context-Aware Applications
Structuring context aware applications is important for modularising their implementation. The modularization is necessary for re-use and sharing of software and hardware components. For this end, a five-layer model for structuring context aware applications is presented. The layers are Physical, Data, Semantic, Inference and Application. (An example case involving a context aware mobile terminal in various user roles has been devised and implemented and this case is then mapped on to the five-layer model giving an example of its use. NOT DISCUSSED IN THIS POSITION PAPER)
2993896
An Efficient Iterative Pose Estimation Algorithm
We propose a novel model-based algorithm which finds the 3D pose of an object from an image by breaking down the estimation process into two linear processing stages, namely the depth recovery and the pose calculation. The depth recovery stage determines the new positions of the model point set in 3D space whereas the pose calculation step is a least-square estimation of the transformation parameters between the point set formed from the previous stage and the model set. The estimates are iteratively refined until converged. The advantage of using our algorithm is that the computational cost is much reduced. We test our algorithm by applying it to both synthetic as well as real time head tracking problem with satisfactory results.
30930498
Chinese document indexing based on a new partitioned signature file: Model and evaluation
In this article we investigate the use of signature files in Chinese information retrieval system and propose a new partitioning method for Chinese signature file based on the characteristic of Chinese words. Our partitioning method, called Partitioned Signature File for Chinese (PSFC), offers faster search efficiency than the traditional single signature file approach. We devise a general scheme for controlling the trade-off between the false drop and storage overhead while maintaining the search space reduction in PSFC. An analytical study is presented to support the claims of our method. We also propose two new hashing methods for Chinese signature files so that the signature file will be more suitable for dynamic environment while the retrieval performance is maintained. Furthermore, we have implemented PSFC and the new hashing methods, and we evaluated them using a large-scale real-world Chinese document corpus, namely, the TREC-5 (Text REtrieval Conference) Chinese collection. The experimental results confirm the features of PSFC and demonstrate its superiority over the traditional single signature file method.
62724310
3D model reconstruction by constrained bundle adjustment
The accuracy of the reconstruction of 3D objects using vision-based techniques depends ultimately on an optimization technique known as bundle adjustment. However, direct application of bundle adjustment fails to make full use of the constraints inherent in the objects' motion. Most of the scanner systems available today use a turntable to rotate an object so as to capture images of the object from different view points. For these systems, the motion of the object is constrained to rotate around a fixed axis. By incorporating this constraint into the traditional bundle adjustment method, we show that a more accurate reconstructed model can be obtained. This "constrained" bundle adjustment method must be useful in the design of low-cost, yet accurate, 3D scanners for use in manufacturing and entertainment industry.
1581000
Extracting and representing cross-language dependencies in diverse software systems
This paper presents an approach for dealing with multi-language software systems. Much of the focus of reverse engineering tools is in analyzing software systems written in one programming language. Nowadays, the abundance of new technologies and languages used to ease application development raises new challenges for reverse engineers. Therefore, this paper focuses on finding cross-language dependencies in such diverse, heterogeneous software systems. Our approach uses source navigator extractors to produce the facts inside each language. Then, we show an example for finding Java Native Interface (JNI) dependencies between facts from Java and C/C++ code. The integrated facts are produced in GXL form, and conform to a unified schema introduced in the paper. This approach is useful from several perspectives. It illustrates how to retrieve the dependencies from software systems written in more than one programming language. Also, the generated facts conform to the GXL format, which is accepted by many reverse engineering tools. The usefulness and scalability of the approach are tested in a case study.