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;

theorem
  X does not overlap EmptyMS I
proof
  assume X overlaps EmptyMS I;
  then ex x st x in X & x in EmptyMS I by Th11;
  hence contradiction by Th124;
end;
