  The proof of 4-dimensional cosmological constant is given for the
10-dimensional supergravity-super-Yang-Mills theory. Supersymmetry is broken at
will. The proof is very simple and it is based on the scale invariance of the
theory but it assumes a nouvelle interpretation of quantum theory or rather
that of Planck constant. Proof utilizes the supergravity-super-Yan-Mills
formulation with a possible stringy correction. A purely stringy proof is under
consideration.
