In my research in functional analysis, I came across this rather simple result:
For a normed algebra A over $ \mathbb{C} $ with unit, in which multiplication (right, right and left is commutative)are both continuous w.r.t the norm defined, such that A with this norm is a Banach space, there exists an equivalent norm with respect to which A is a Banach Algebra.
I was wondering, is the existence of a unit in A truly necessary, or can we guarantee the existence of an equivalent norm such that A is a Banach algebra?