Dear members
please help me with the proof of this theorem
Let S be a semigroup such that $l^(s)$ is amenable. then
$|E(S)|^(1/2)\leq AM(l^(s))$
if the idempotents of S commute, then
$|E(S)|\leq AM(l^(s))$
definition:
let A be amenable Banach algebra we set
AM(A)=inf{C>0 :A is C-amenable}