A supplement to the paper "Differentiable roads for real functions" by J. G. Ceder
Specializing a recently developed axiomatic theory of non-absolutely convergent integrals in , we are led to an integration process over quite general sets with a regular boundary. The integral enjoys all the usual properties and yields the divergence theorem for vector-valued functions with singularities in a most general form.
A closed subset of the real line which is right porous but is not -left-porous is constructed.