Skip to main content
9 events
when toggle format what by license comment
Aug 13, 2021 at 16:25 history undeleted Korn
Aug 13, 2021 at 16:25 history deleted Korn via Vote
Aug 13, 2021 at 16:25 history undeleted Korn
Aug 11, 2021 at 18:32 history deleted Korn via Vote
Aug 10, 2021 at 16:56 comment added Yemon Choi Also, to elaborate on Taka's point that Prop 2.2 can be "proved directly": for most practical/intuitive purposes, the better definition of amenability for Banach algebras is in terms of the existence of bounded approximate diagonals. Once you have such gadgets, there is a simple way to use them to average projections to get projections which respect the algebra action, and hence get the (total) reduction property
Aug 10, 2021 at 16:50 comment added Yemon Choi For the benefit of other readers: as Taka has pointed out, Theorem 2.1 characterizes the total reduction property in terms of the vanishing of certain degree-1 cohomology groups. The passage quoted above shows that amenability, as originally defined by Johnson, is equivalent to vanishing of an even larger class of degree-1 cohomology groups.
Aug 10, 2021 at 2:07 comment added Narutaka OZAWA That's because the assumption of Theorem 2.1 is satisfied. (Also it's easy to show Proposition 2.2 directly.)
Aug 9, 2021 at 22:50 review First posts
Aug 9, 2021 at 23:56
Aug 9, 2021 at 22:42 history asked Korn CC BY-SA 4.0