|
In functional analysis a Banach function algebra on a compact Hausdorff space ''X'' is unital subalgebra, ''A'' of the commutative C *-algebra ''C(X)'' of all continuous, complex valued functions from ''X'', together with a norm on ''A'' which makes it a Banach algebra. A function algebra is said to vanish at a point p if f(p) = 0 for all . A function algebra separates points if for each distinct pair of points , there is a function such that . For every define . Then is a non-zero homomorphism (character) on . Theorem: A Banach function algebra is semisimple (that is its Jacobson radical is equal to zero) and each commutative unital, semisimple Banach algebra is isomorphic (via the Gelfand transform) to a Banach function algebra on its character space (the space of algebra homomorphisms from ''A'' into the complex numbers given the relative weak * topology). If the norm on is the uniform norm (or sup-norm) on , then is called a uniform algebra. Uniform algebras are an important special case of Banach function algebras. ==References== * H.G. Dales ''Banach algebras and automatic continuity'' 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Banach function algebra」の詳細全文を読む スポンサード リンク
|