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1995 Fiscal Year Final Research Report Summary

Research on Algorithms for Discrete Optimization Problems with Dynamic and On-Line Environments.

Research Project

Project/Area Number 05452122
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field Engineering fundamentals
Research InstitutionUniversity of Tokyo

Principal Investigator

IMAI Hiroshi  University of Tokyo, Graduate School of Science, Associate Professor, 大学院・理学系研究科, 助教授 (80183010)

Co-Investigator(Kenkyū-buntansha) IMAI Keiko  Chuo University, Faculty of Science and Engineering, Associate Professor, 理工学部, 助教授 (70203289)
Project Period (FY) 1993 – 1995
KeywordsOn-line algorithm / Dynamic shortest paths / Dynamic computational geometry / Continuum algorithm / Real-time algorithm
Research Abstract

The aim of this research is to develop efficient algorithms for discrete optimization problems under dynamic and on-line environments. Many practical problems have dynamic and on-line natures, and algorithms should be newly designed to handle dynamic and on-line factors.
First, we consider the dynamic shortest path problem where the distances of edges vary dynamically. This problem arises in real-time route navigation system where traffic jams makes the edge costs higher. We have developed A^*-based algorithms which make clever use of past solutions. Other techniques such as bidirectional search are also investigated. Also, to cope with future dynamic situations, a new algorithm to compute multiple candidates for route navigation in the given static environment is developed.
We formulate probelems of sharing information in distributed systems as an on-line model, and developed efficient on-line algorithms. The on-line nature is inherent in the distributed system, and we mainly consider page migration and replication probelms. To evaluate the on-line algorithms the so-called competitive ratio is used. Efficient algorithms in term of this ratio have been derived. Randomized techniques are demonstrated to be powerful for on-line problems.
Dynamic computational geometry is also investigated, especially the Voronoi diagram for dynamically moving points. The combinatorial complexity of dynamic Voronoi diagram is shown, together with its efficient construction algorithm. This is further applied to geometric clustering problem which have both discrete and continuous aspects. Randomized algorithms are developed by making use of these two aspects.
We have thus clarified fundamental structures of dynamic and on-line problems, and developed new paradigms to solve this new type of problems.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] S.Hasegawa,H,Imai and M.Ishiguro: "6-Appreximations of k-Label Spaces." Theoretical Computer Science. 137. 145-157 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Shibuya,T.Ikeda,H.Imai,S.Nishimura,H.Shimoura and K.Tenmoku: "Finding a Realistic Detour by AI Seavch Technidnes." Proceedings of the 2nd World Congress on Intelligent Transport Systems(ITS′95),Yokohama. 4. 2037-2044 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] S.Albers and H.Koga: "Page Migration with Limited Local Memory." Proceedings of the 4th International Workship on Algorithms and Data Structure(WADS'95),Lecture Notes in Computer Science. 955. 147-158 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.Imai and M.Inaba: "Geometric Clustering with Applications." The Third International Congress on Industrial and Applied Mathematics(ICIAM'95).Book of Abstracts. 124-

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Shibuya: "Finding K Shortest Paths by AI Search Technidues." Cooperative Reseavch Repovt,“Optimization:Modeling and Algorithms."The Institute of Statistical Mathematics.77. 212-222 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 今井浩、今井桂子: "組合せ幾何学のアルゴリズム" 共立出版, (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] S.Hasegawa, H.Imai and M.Ishiguro: "E-Approximations of K-Label Spaces" Theoretical Computer Science. Vol. 137. 145-157 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Shibuya, T.Ikeda, H.Imai S.Nishimura, H.Shimoura and K.Tenmoku: "Finding a Realistic Detour by AI Search Techniques." Proceedings of the 2nd world Congress on Intelligent Transport Systems (ITS'95), Yokonama. vol.4. 2037-2044 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] S.Albers and H.Koga: "Page Migration with Limited Local Memory." Proceedings of the 4th International Workshop on Algorithms and Data Structure (WADS'95), Lecture Notes in Computer Science. vol.955. 147-158 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H.Imai and M.Inaba: "Geometric Clustering with Applications." The Third International Congress on Industrial and Applied Mathematics (ICIAM'95), Book of Abstracts. 124

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Shibuya, Finding K: "Shortest Paths by AI Serch Techniques" Cooperative Research Report, "Optimization Modeling and Algorithms, "The Institute of Statistical Mathematics.vol.77. 212-222 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H.Imai and K.Imai: Algorithms in Combinatrial Geometry. Kyoritsu, Tokyo, (1995)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1997-03-04  

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