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## ACM SIGMOD日本支部 講演会(チュートリアル) |

## 「Summarizing Level-two Topological Relationships in Large Spatial Datasets」 |

講演者：Prof. Xuemin Lin (University of New South Wales) |

日時：2005年12月23日(金) 14:00 - 15:00 |

開催場所：東京大学生産技術研究所 会議室A(Ew-501) |

主催：日本データベース学会・ACM SIGMOD日本支部 共催 |

支部長：北川 博之 |

## Abstract |

Summarizing topological relations is fundamental to many spatial applications including spatial query optimization. In this talk, we present several novel techniques to effectively construct cell density based spatial histograms for range (window) summarizations restricted to the four most important level-two topological relations: contains, contained, overlap, and disjoint. We first present a novel framework to construct a multiscale Euler histogram in 2D space with the guarantee of the exact summarization results for aligned windows in constant time. To minimize the storage space in such a multiscale Euler histogram, an approximate algorithm with the approximate ratio 19/12 is presented, while the problem is shown NP-hard generally. To conform to a limited storage space where a multiscale histogram may be allowed to have only k Euler histograms, an effective algorithm is presented to construct multiscale histograms to achieve high accuracy in approximately summarizing aligned windows. Then, we present a new approximate algorithm to query an Euler histogram that cannot guarantee the exact answers; it runs in constant time. |

参加条件：どなたでもご参加頂けます．参加費は無料です． |

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