Journal of Operator Theory

Volume 32, Issue 2, Fall 1994 pp. 209-241.

Angles between two subfactors

Authors: Takashi Sano (1) and Yasuo Watatani (2)
Author institution:Department of Mathematics, Faculty of Science, Kyushu University, Fukuoka, 812, JAPAN. Current address: Department of Mathematics, Faculty of Science, Yamagata University, Yamagata, 990, JAPAN
Department of Mathematics, Faculty of Science, Hokkaido University, Sapporo, 060, JAPAN. Current address: Graduate School of Mathematics, Kyushu University, Ropponmatsu, Fukuoka 810, JAPAN

Summary: We introduce angles between two subfactors of a type II_1 factor to study their relative position. We calculate angles for certain pairs. We also determine when fixed point algebras form a commuting square.

Keywords: Angle, subfactor, Jones index, commuting square, co-commuting square.

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