A cancellative amenable ascending union of nonamenable semigroups
We construct an example of a cancellative amenable semigroup which is the ascending union of semigroups, none of which are amenable.
We construct an example of a cancellative amenable semigroup which is the ascending union of semigroups, none of which are amenable.
We use a total order on Thompson’s group to show that the group ring has no minimal non-zero ideals.
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