ABSTRACT
The problem of identifying conditions under which the function his monotone non-decreasing has been much discussed, Benhabib and Nishimura (1985), Majumdar and Nermuth ( 1982), Dechert and Nishimura (1983), Majumdar and Mitra ( 1994a), and Mitra and Ray ( 1984). Instead of presenting the most general technical conditions (which involve the notion of "supermodular" functions studied by Topkis ( 1968), see also Ross ( 1983 ), we present a set of sufficient conditions in the "differentiable" case. Let IR!++ denote the set of all positive numbers. Also, let 11' 12 , w22 be the usual second-order partial derivatives of w w.r.t. the first and second arguments.
