(*

  †bungen zur Vorlesung Informatik I, WS 2003/04
  Programmieraufgabe P-25 :: grammatik.ml
  ----------------------------------------------  
  Leonhard Fellermayr, Mat. Nr. 22128130XXXX

*)

let anfang s = String.get s 0;;

let rest s = String.sub s 1 ((String.length s)-1);;

let rec bStern s =
  if (String.length s) == 0 then true
  else if (anfang s) == 'b' then bStern (rest s)
  else false;;

let rec aSternbStern s =
  if (bStern s) then true
  else if (anfang s) == 'a' then aSternbStern (rest s)
  else false;;

let wort s =
  if (anfang s) == 'a' && aSternbStern (rest s) then true
  else false;;