%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%                                                                %%
%%    Pereira and Shieber, Program 3.12 pp.78-9                   %%
%%    (corrected)                                                 %%
%%                                                                %%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%%%% Stuff to overcome Sictus' ever-so-helpful  abbreviation of list terms

portray(Term) :- is_list(Term), write(Term).

is_list([]).
is_list([_|_]).

%%%% End of stuff

s --> np, vp.

np --> det, n, optrel.
np --> pn.

vp --> tv, np.
vp --> iv.

optrel --> [].
optrel --> [that], vp.

det --> [Det], {det(Det)}.
det(a).
det(the).
det(some).
det(every).

n --> [N], {n(N)}.
n(author).
n(book).
n(program).
n(programmer).
n(professor).
n(student).

pn --> [PN], {pn(PN)}.
pn(begriffsschrift).
pn(principia).
pn(lunar).
pn(shrdlu).
pn(bertrand).
pn(gottlob).
pn(terry).
pn(bill).

tv --> [TV], {tv(TV)}.
tv(pleased).
tv(met).
tv(ran).
tv(wrote).

iv --> [IV], {iv(IV)}.
iv(halted).

%| ?- s([bertrand, wrote, a, program, that, halted],[]).
%
%yes
%| ?-