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ew    m_` 6>FGBCB MUf Yusuke YAMAMOTO Taro TEZUKA
Adam JATOWT Katsumi TANAKA  tw * + d | K % 1 &  \ * T) 31 ] + s a* Web {  7I ;I %+ [ N
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T 4 Q! 1 V P )+ 1 u v)  $ 1 \' * h Web L % Y 2$  1 ' * h 
$ Y 2 $ 1 4 Wx ! 1 &% u  ( }
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determine the trustworthiness of propositions they may beunsure about. For example, a user may want to know if aproposition, such as "the number of countries in European
Union is 25" is true or not. Conventional search engines
cannot directly provide answers to suchquestions. The trustworthiness of propositions is estimated in
our method by aggregating knowledge from the Web and byanalyzing creation time of pages. We also propose a method
for estimating changes in the popularity of propositions intime by analyzing how many pages
contained the proposition in selected time periods and how
continuously they appeared in the Web. Thanks to this, users
can know whether theproposition has been true or false during specific periods.

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ĞWeb EO4ó_cÒ)Āb' ª%('ğ[1] Internet Archive. http://www.archive.org/web/web.php[2] Ebbinghaus, H., Memory: A Contribution toExperimental Psychology, Thoemmes Press, 1913.
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Answering: Review of the Main Approaches, ThirdInternational Conference on Information Technologyand Applications (ICITA 2005), pp. 514-519, 2005.
[6] Kleinberg, J., Bursty and Hierarchical Structure inStreams, Data Mining and Knowledge Discovery, Vol. 7Iss. 4, Kluwer Academic Publishers, 2003.

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