 If "V" is some topological space, for example a subset of some R"n", real- or complex-valued continuous functions on "V" form a commutative ring.The same is true for differentiable or holomorphic functions, when the two concepts are defined, such as for "V" a complex manifold.In contrast to fields, where every nonzero element is multiplicatively invertible, the concept of divisibility for rings is richer.