1. Integrability Demand function x(p, w)(c 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 x(p, w ) That the integrability problem1.Integrability • Demand function x(p,w) (c.d.) is HD0, 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 x(p,w)? That the integrability problem