Semisimple commutative Banach algebra
= Semisimple commutative Banach algebra
{title2=$\operatorname{rad}A=0$}
A commutative <Banach algebra> is semisimple when its <Jacobson radical> is zero. For a complex unital <Banach algebra> this is equivalent to injectivity of the <Gelfand transform>. This condition concerns the <Jacobson radical>; it does not assert a finite product decomposition as in finite-dimensional semisimple algebra theory.