S -> NP VP
VP -> IV | TV NP | DTV NP NP | TV NP PP 
IV -> 'left'
TV -> 'know' | 'knows' | 'likes' | 'read' | 'saw'  | 'helps' | 'introduced'
DTV -> 'gave'
NP -> PRO | DET N | NP CONJ NP | 'John' | 'Mary' | 'Carlos' | 'Boston' | 'Thursday' | 'everybody'
N -> ADJ N | 'book' | 'shirt' | 'student' | 'man' | 'woman' | 'men' | 'women' | 'telescope'
PRO -> 'her' | 'them' | 'she' | 'they' | 
DET -> 'a' | 'the' | 'some'
ADJ -> 'red' | 'old'
PP -> P NP
P -> 'with' | 'on' | 'to'
CONJ -> 'and'


%%COMMENTS
%%The top-down parser has problems when trying to use the left recursive rule:
NP -> NP CONJ NP


The left recursion can be eliminated by replacing the rule as following:

NP -> 'men' NP1 | 'women' NP1 | ADJ NP NP1
NP1-> CONJ NP NP1 | 
CONJ -> 'and'
ADJ --> 'old '