We will show that the duality for regular weight system introduced by K. Saito can be interpreted as the duality for the orbifoldized Poincare polynomial χ(W,G)(y, ȳ). Introduction In [A], Arnold discovered a strange duality among the 14 exceptional singularities. This was interpreted by Dolgachev, Nikulin and Pinkham in terms of the duality between algebraic cycles and transcendental cycles on...