1.Integrability Demand function x(p,w)(.d.) is HDO, satisfied Walras Law and have a substitution matrix S(p,w) is s.n.s.d. for any (p,w), if it's deduced by rational preference. And if we observed an x(p,w) satisfied such conditions, can we find a preference to rationalization(p,w)? That the integrability problem