Set Theory Seminar in Kobe

以下の要領でセミナーを開催します．

日時：2010年10月21日（木）15:00-17:00 場所：神戸大学自然科学総合研究棟3号館4階421室（プレゼンテーション室） 講演者：池上 大祐（ヘルシンキ大学） 題目：Wadge reducibility for the real line

アブストラクト： In 1968, Wadge introduced Wadge reducibility for the Baire space, that is an analogue of many-one reducibility in recursion theory. For two subsets A, B of Baire space, we say A is Wadge reducible to B if there is a continuous function from the Baire space to itself such that A = f^{-1} (B). We can introduce Wadge degrees in the same way as many-one degrees. In the 1970s and 1980s, set theorists in California developed a beautiful theory of Wadge degree structure under ZF+AD+DC. On the other hand, we can easily introduce Wadge reducibility on any topological space as above. In 1998, Woodin claimed that Wadge reducibility on the real line is totally different from that on the Baire space. In this talk, we compare them and claim how different they are. This is joint work with Hisao Tanaka and Philipp Schlicht.

交通：阪急六甲駅またはJR六甲道駅から神戸市バス36系統「鶴甲団地」 行きに乗車，「神大本部工学部前」停留所下車，徒歩すぐ． http://www.kobe-u.ac.jp/info/access/rokko/rokkodai-dai2.htm

連絡先：ブレンドレ ヨーグ [email protected]