Axiomatic Differential Geometry II-1 Vector Fields

In our previous paper entitled "Axiomatic differential geometry -towards model categories of differential geometry-, we have given a category-theoretic framework of differential geometry. As the first part of our series of papers concerned with differential-geometric developments within the above axiomatic scheme, this paper is devoted to vector fields. The principal result is that the totality of vector fields on a microlinear and Weil exponential object forms a Lie algebra.