  We use a method involving elementary submodels and a partial converse of
Foran lemma to prove separable reduction theorems concerning Suslin
sigma-P-porous sets where "P" can be from a rather wide class of porosity-like
relations in complete metric spaces. In particular, we separably reduce the
notion of Suslin cone small set in Asplund spaces. As an application we prove a
theorem stating that a continuous approximately convex function on an Asplund
space is Frechet differentiable up to a cone small set.
