(1)V(x,y)=min{x,y};U(V,z)=V+z;

(2)当px+py>=pz时

x(p,m)=0;z(p,m)=m/pz;

当px+py<pz时

x(p,m)=m/(px+py);z(p,m)=0;

(3)当px+py>=pz时

v(p,m)=m/pz;

当px+py<pz时

v(p,m)=m/(px+py);