You should be able to get it as a corollary of the lemma that given two disjoint convex subsets U and V of R^n (which are non-zero distance apart), there exists an affine function f on R^n such that f(u) > 0 for all u in V and f(v) < 0 for all v in V.
Our two convex sets being (1) the image of the simplex under the F_i : i = 1 … n and (2) the “negative quadrant” of R^n (i.e. the set of points all of whose co-ordinates are non-positive.)
You should be able to get it as a corollary of the lemma that given two disjoint convex subsets U and V of R^n (which are non-zero distance apart), there exists an affine function f on R^n such that f(u) > 0 for all u in V and f(v) < 0 for all v in V.
Our two convex sets being (1) the image of the simplex under the F_i : i = 1 … n and (2) the “negative quadrant” of R^n (i.e. the set of points all of whose co-ordinates are non-positive.)
Yeah, I think that works. Nice!