Bousfield Classes and Ohkawa's Theorem

This volume originated in the workshop held at Nagoya University, August 28–30, 2015, focusing on the surprising and mysterious Ohkawa's theorem: the Bousfield classes in the stable homotopy category SH form a set. An inspiring, extensive mathematical story can be narrated starting with Ohkawa's theorem, evolving naturally with a chain of motivational questions:  Ohkawa's theorem states that the Bousfield classes of the stable homotopy category SH surprisingly forms a set, which is still ve