fst 0 Z nil fst s X cons Y Z cons Y n__fst activate X activate Z from X cons X n__from s X add 0 X X add s X Y s n__add activate X Y len nil 0 len cons X Z s n__len activate Z fst X1 X2 n__fst X1 X2 from X n__from X add X1 X2 n__add X1 X2 len X n__len X activate n__fst X1 X2 fst X1 X2 activate n__from X from X activate n__add X1 X2 add X1 X2 activate n__len X len X activate X X fst 2 0 0 nil 0 s 1 cons 2 n__fst 2 activate 1 from 1 n__from 1 add 2 n__add 2 len 1 n__len 1 FULL ./TRS/TRCSR/Ex2_Luc03b_Z.trs