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