2. T: Type
3. G: Grammar(V;T)
4. l: (V+T)*
5. m: (V+T)*
6. n: (V+T)*
7. a1: (V+T)* List
8. l = a1[0]
9.
i:
(||a1||-1). a1[i] 
a1[(i+1)]10. a1[(||a1||-1)] = m
11. a: (V+T)* List
12. m = a[0]
13.
i:(||a||-1). a[i] a[(i+1)]14. a[(||a||-1)] = n
a:((V+T)* List). l = a[0] & (i:(||a||-1). a[i] a[(i+1)]) & a[(||a||-1)] = n
