reserve i,j,e,u for object;
reserve I for set; 
reserve x,X,Y,Z,V for ManySortedSet of I;
reserve I for non empty set,
  x,X,Y for ManySortedSet of I;
reserve I for set,
  x,X,Y,Z for ManySortedSet of I;
reserve X for non-empty ManySortedSet of I;
reserve D for non empty set,
  n for Nat;
reserve X,Y for ManySortedSet of I;

theorem
 for I being set, Y being non empty set
 for p being Y-valued I-defined Function
  ex s being Y-valued ManySortedSet of I st p c= s
 proof
  let I be set, Y being non empty set;
  let p be Y-valued I-defined Function;
   set h = the Y-valued ManySortedSet of I;
  take h+*p;
  thus p c= h+*p by FUNCT_4:25;
 end;
