-- example of probabilistic grammar from Jurafsky & Martin p. 449
-- AR 1/11/2005

PredVP.  S   ::= NP VP ; --# prob 0.80 
PredAux. S   ::= Aux NP VP ; --# prob 0.15
JustVP.  S   ::= VP ; --# prob  0.05

DetNO.   NP  ::= Det Nom ; --# prob 0.20
PNounNP. NP  ::= PNoun ; --# prob 0.35
NomNP.   NP  ::= Nom ; --# prob 0.05
ProNP.   NP  ::= Pro ; --# prob 0.40

NounNom.  Nom ::= Noun ; --# prob 0.75
CompNom.  Nom ::= Noun Nom ; --# prob 0.20
PNounNom. Nom ::= PNoun Nom ; --# prob 0.05

IntrVP. VP  ::= Verb ; --# prob 0.55
TrVP.   VP  ::= Verb NP ; --# prob 0.40
DitrVP: VP  ::= Verb NP NP ; --# prob 0.05

that. Det ::= "that" ; --# prob 0.05
the.  Det ::= "the" ; --# prob 0.80
a.    Det ::= "a" ; --# prob 0.15

bookN.   Noun  ::= "book" ; --# prob 0.10
flights. Noun  ::= "flights" ; --# prob 0.50
meal.    Noun  ::= "meal" ; --# prob 0.40

bookV.    Verb  ::= "book" ; --# prob 0.30
includeV. Verb  ::= "include" ; --# prob 0.30
want.     Verb  ::= "want" ; --# prob 0.40

can.  Aux ::= "can" ; --# prob 0.40
does. Aux ::= "does" ; --# prob 0.30
do.   Aux ::= "do" ; --# prob 0.30

TWA.    PNoun ::= "TWA" ; --# prob 0.40
Denver. PNoun ::= "Denver" ; --# prob 0.60

you. Pro ::= "you" ; --# prob 0.40
I.   Pro ::= "I" ; --# prob 0.60

-- > p -prob "can you book TWA flights"
--
-- 4.3200000000000016e-7
-- 3.7800000000000013e-7
-- PredAux can (ProNP you) (TrVP bookV (NomNP (PNounNom TWA (NounNom flights))))
-- PredAux can (ProNP you) (DitrVP bookV (PNounNP TWA) (NomNP (NounNom flights)))
-- [0.15,  0.40,0.40, 0.40, 0.05,  0.30,  0.35,   0.40, 0.05,  0.75,   0.50]
--
-- J&M have different figures, but they seem to be wrong. For
-- instance, their products have 12 terms although the trees have only
-- 11 constructors.