s(String) :- concat_atom(Words, ' ', String), sentence(Words,[]).

sentence --> article, noun, verb.

article --> [a]; [the].

noun --> [dog]; [cat]; [girl]; [boy].

verb --> [ran]; [talked]; [slept].
verb([Verb|Left], Left) :- verb0(Verb).

verb0(jumped). verb0(ate). verb0(computed).

