theorem Th36:
  p is atomic implies Vars(p,V) = variables_in(the_arguments_of p,
V) & Vars(p,V) = { (the_arguments_of p).k : 1 <= k & k <= len (the_arguments_of
  p) & (the_arguments_of p).k in V }
proof
  assume p is atomic;
  hence Vars(p,V) = variables_in(the_arguments_of p, V) by Lm2;
  hence thesis;
end;
