# zbMATH — the first resource for mathematics

Isomorphisms of algebras of smooth functions revisited. (English) Zbl 1082.46020
Let $$M_1,M_2$$ be Hausdorff smooth finite-dimensional manifolds. Let $$C^{\infty}(M_i,F)$$ denote the algebra of smooth functions over the real or complex scalar field $$F$$. In this interesting paper, the author gives a proof of a Banach-Stone type theorem which describes an algebra isomorphism between these spaces as implemented by a pull back by a smooth diffeomorphism between the manifolds. It is not assumed that the manifolds are second countable or paracompact.
The canonical approach is to identify ideals of co-dimension one (or, equivalently, multiplicative functionals) with points of the manifold. Unlike this approach, the author calls an ideal of co-dimension one ‘distinguished’ if it has an element which is not in any other ideal of co-dimension one. With this notation, one of the main steps of the proof is to establish that $$p \rightarrow \{f : f(p) = 0\}$$ is a homeomorphism when the set of distinguished ideals of co-dimension one is equipped with the Stone topology. It is also noted that J. Mrčun [Proc. Am. Math. Soc. 133, No. 10, 3109–3113 (2005; Zbl 1077.58005)] also gave a proof of Theorem 1, using ‘characteristic sequences of functions’ instead of characterizations of multiplicative functionals.

##### MSC:
 46E25 Rings and algebras of continuous, differentiable or analytic functions 58A05 Differentiable manifolds, foundations 58C25 Differentiable maps on manifolds 54C40 Algebraic properties of function spaces in general topology
Full Text: