Current Research Projects of Our Department

• Compressing and Indexing Documents Including Japanese Texts (H.Yokoo and M.Yasukawa)
• Design of Graphs for Computer Networks (Y.Shibata and S.Osawa)
• Analysis of Stochastic Systems (Y.Seki)
• Type Theory and its Applications to Programming Languages (H.Yokouchi)
• Design and Analysis of Approximation Algorithms (K.Yamazaki)
• Satellite Communication Systems (Y.Onozato)
• Load Balancing of WWW Traffic (Y.Onozato and U.Yamamoto)
• Computer Vision (N.Ohta)
• Protein Structure and Its Folding-Unfolding Process (S.Miyazawa)

• Compressing and Indexing Documents Including Japanese Texts (H.Yokoo and M.Yasukawa)

  One of the most serious problems in this information age is the information explosion. The challenge of storing and retrieving large volumes of raw data continues to grow. This project encompasses compressing large document collections and indexing such collections so that relevant material can be retrieved. Our particular focus is on proper treatment of Japanese texts.

• Design of Graphs for Computer Networks (Y.Shibata and S.Osawa)

  This project investigates various graph families for computer network design. We are particularly interested in graph decomposition, factorization and embedding problems, and related graph algorithms. These problems are fundamental to study the efficiency and reliability of communication on computer networks. One of our recent achievements is the factorizability of directed complete graphs into de Bruijn graphs and Kautz graphs.

• Analysis of Stochastic Systems (Y.Seki)

  This project investigates mathematical theories and simulation analysis of various typed stochastic systems used as models of computer systems, manufacturing facilities and others. One of our recent achievements is a development of a closed-form transient solution to M/M/c queueing systems. This solution is useful for numerical calculation by the lattice path counting method.

• Type Theory and its Applications to Programming Languages (H.Yokouchi)

  This project is aimed at investigating type systems for programming languages. Recent work attempts to develop a type system with set operations that captures various language constructs manipulating data types such as operator overloading and inheritance in object-oriented programming.

• Design and Analysis of Approximation Algorithms (K.Yamazaki)

  Optimization graph problems such as finding a maximum independent set, bandwidth and pagenumber are considered. In particular, we are investigating the inapproximability of the bandwidth problem, designing approximation algorithms for finding a weighted maximum independent set, and analyzing the approximability/nonapproximability of the pagenumber problem.

• Satellite Communication Systems (Y.Onozato)

  This project investigates mainly performance evaluations of multiple access schemes for various typed satellite communication systems. We are particularly interested in developing multimedia teleconference systems via a satellite for tele-medicine and tele-education, and in analyzing their performance.

• Load Balancing of WWW Traffic (Y.Onozato and U.Yamamoto)

  Locating mirror servers is one of the solutions to balance the load of WWW traffic on the Internet. The aim of this project is to investigate the characteristics of access to WWW servers on various network models, and to develop automatic server selection methods to provide the most appropriate server for each client.

• Computer Vision (N.Ohta)

  This project investigates mathematical theories of 3-D reconstruction from images, statistical analysis of the reliability of the reconstructed 3-D representation, optimization techniques for maximizing the accuracy of computation in the presence of noise, 3-D geometric modeling for autonomous robot navigation, system implementation of real image understanding based on stereo and motion, and object-oriented graphics systems for 3-D displaying environments. Image processing techniques for detecting optical flow are also studied.

• Protein Structure and Its Folding-Unfolding Process (S.Miyazawa)

  The purpose of this study is to understand how a protein can fold a unique native structure from its amino acid sequence, and to understand the origin of stability of protein native structure and the all-or-none characteristics of protein denaturation. Full understanding a protein folding-unfolding process includes descriptions of the denatured state as well as native structure.