s(s(NpT,VpT)) --> np(NpT), vp(VpT).

np(np(DetT,NT)) --> det(DetT), n(NT).
np(np(PnT)) --> pn(PnT).

vp(vp(ViT)) --> vi(ViT).
vp(vp(VtT,NpT)) --> vt(VtT), np(NpT).


%% Lexicon

det(det(a)) --> [a].
det(det(the)) --> [the].

n(n(bride)) --> [bride].
n(n(nurse)) --> [nurse].
n(n(yakuza)) --> [yakuza].
n(n(whiskey)) --> [whiskey].

pn(pn(bill)) --> [bill].
pn(pn(gogo)) --> [gogo].

vi(vi(whistles)) --> [whistles].
vi(vi(fights)) --> [fights].

vt(vt(drinks)) --> [drinks].
vt(vt(kills)) --> [kills].