12:30 受付開始
12:50-13:00 支部長によるプログラム紹介 喜連川 優（東大 生研概念センタ）
1. 13:00-14:00
Kyu Whang Young(KAIST) TBA
In this talk, we propose a new subsequence matching method, DualMatch,
which exploits duality in constructing windows and significantly
improves performance. DualMatch divides data sequences into disjoint
windows and the query sequence into sliding windows, and thus, is a dual
approach of the one by Faloutsos et al. (FRM in short), which divides
data sequences into sliding windows and the query sequence into disjoint
windows. We formally prove that our dual approach is correct, i.e., it
incurs no false dismissal. We also prove that, given the minimum query
length, there is a maximum bound of the window size to guarantee
correctness of DualMatch and discuss the effect of the window size on
performance. FRM causes a lot of false alarms (i.e., candidates that do
not qualify) by storing minimum bounding rectangles rather than
individual points representing windows to avoid excessive storage space
required for the index. DualMatch solves this problem by directly
storing points, but without incurring excessive storage overhead.
Experimental results show that, in most cases, DualMatch provides large
improvement in both false alarms and performance over FRM, given the
same amount of storage space. In particular, for low selectivities(less
than 10E-4), DualMatch significantly improves performance up to
430-fold. On the other hand, for high selectivities(more than 10E-2), it
shows a very minor degradation(less than 29%). For selectivities in
between (10E-4~10E-2), DualMatch shows performance slightly better than
that of FRM. DualMatch is also 4.10~25.6 times faster than FRM in
building indexes of approximately the same size. Overall, these results
indicate that our approach provides a new paradigm in subsequence
matching that improves performance significantly in large database
applications.
2. 14:00-15:30
「ACM SIGMOD2002国際会議報告(1)」
櫻井保志(NTT サイバースペース研究所)
<休憩 10分>
3. 15:40-17:10
「ACM SIGMOD2002国際会議報告(2)」
櫻井保志(NTT サイバースペース研究所)
<休憩 5分>
4. 17:15-18:15
「ユビキタスコンピューティングへの動きと新しい情報環境の問題」
木實新一(University of Colorado at Boulder)
小型・高性能・低価格化したコンピュータは、ユビキタスな存在
として環境の中に溶け込み、人間の様々な活動に新たな形で
影響を与えつつあります。最新の動向を、欧米での研究・ビジ
ネスの事例や講演者自身の取り組みを含めて紹介し、次第に
姿をあらわしつつある新しい情報環境の問題を論じます。 |