It is also worth remarking that the paper also provides results for the sign of the derivatives greater than k - 1 of the Green function of the problem (2.20), in particular Theorem
3, which improve previous results as far as the authors are aware.
We assume familiarity with the properties of pseudo-convergent sequences, see  for more details, and in particular Theorem
3, Lemmas 4 and 8.
Computer scientists several years ago used this concept as the basis for the wonderfully counterintuitive notion of a "zero-knowledge proof." Such a scheme permits someone to persuade others that a particular theorem
she has proved is true without giving away anything about how to go about proving the theorem itself (SN: 8/30/86, p.
All that someone else can find out, until the proof itself is finally revealed, is that a particular theorem