皆様， 名古屋大学の木原貴行です．この度，コネチカット大学の Linda Brown Westrick 氏の名古屋訪問の折に，下記の要領で名古屋ロジックセミナーを開催することとなりました．多数のご参加をお待ちしております． 名古屋ロジックセミナー http://www.math.mi.i.nagoya-u.ac.jp/~kihara/logic-seminar.html 日時：8月24日 (木) 15:30〜 場所：名古屋大学大学院情報学研究科棟 314室 講演者：Linda Brown Westrick (コネチカット大学) 題目Uncountable free abelian groups via admissible computability 概要One way to study structures of uncountable cardinality κ is to generalize the notion of computation. Saying that a subset of κ is κ-c.e. if it is Σ^0_1 definable (with parameters, in the language of set theory) over L_κ provides the notion of κ-computability. We may also quantify over subsets of L_κ, providing a notion of a κ-analytic set (here we assume V=L). In this setting, we consider the difficulty of recognizing free groups and the complexity of their bases. For example, if κ is a successor cardinal, the set of free abelian groups of size κ is Σ^1_1-complete. The resolution of questions of this type is more complex for other κ, and a few questions remain open. This is joint work with Greenberg and Turetsky.
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Takayuki Kihara
Graduate School of Informatics, Nagoya University, Japan