## Natural Language Toolkit: feat1.fcfg
##
## Second example of a feature-based grammar, illustrating
## SUBCAT and slash features. Also introduces SBar and embedded
## clauses.
## Used in Feature-Based Grammars chapter.
## 
## Author: Ewan Klein <ewan@inf.ed.ac.uk> 
## URL: <http://nltk.sourceforge.net>
## For license information, see LICENSE.TXT

% start S
# ###################
# Grammar Productions
# ###################

S[-INV] -> NP VP
S[-INV]/?x -> NP VP/?x

S[-INV] -> NP S/NP
S[-INV] -> Adv[+NEG] S[+INV]

S[+INV] -> V[+AUX] NP VP
S[+INV]/?x -> V[+AUX] NP VP/?x

SBar -> Comp S[-INV]
SBar/?x -> Comp S[-INV]/?x

VP -> V[SUBCAT=intrans, -AUX]

VP -> V[SUBCAT=trans, -AUX] NP
VP/?x -> V[SUBCAT=trans, -AUX] NP/?x

VP -> V[SUBCAT=clause, -AUX] SBar
VP/?x -> V[SUBCAT=clause, -AUX] SBar/?x

VP -> V[+AUX] VP
VP/?x -> V[+AUX] VP/?x

# ###################
# Lexical Productions
# ###################
V[SUBCAT=intrans, -AUX] -> 'walk' | 'sing'
V[SUBCAT=trans, -AUX] -> 'see' | 'like'
V[SUBCAT=clause, -AUX] -> 'say' | 'claim'
V[+AUX] -> 'do' | 'can'

NP[-WH] -> 'you' | 'cats'
NP[+WH] -> 'who'

Adv[+NEG] -> 'rarely' | 'never'

NP/NP ->

Comp -> 'that'