Phrase Structure Rules
1. Phrase structure rules
 the grammar contains a set of rules that generate the trees phrase structure rules
o phrase structure rules that will produce the structure of
The child found the puppy in the garden
S
[The child] [found the puppy in the garden]
NP
VP
[The child] [found] [the puppy] [in the garden]
Det N
Vt
NP
PrepP
the puppy Prep NP
Det N
in the garden
Det N
1. S  NP VP
2. VP  Vt NP PrepP
3. NP  Det N
4. PrepP  Prep NP
 these rules describe all the steps in the generation of the phrase structure tree:
1. Begin with rule 1
o create the node S
o one line below it, create the nodes NP and VP
o connect the NP and VP nodes to S
2. Then apply rule 2
o one line below VP, create three nodes VT, NP, and PrepP
o connect each of them to VP
3. Continue with rule 3
o one line below PrepP create a node Prep and its object NP node
o connect the NP node to PrepP
4. Finally, apply rule 4
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o now, below each NP, create two nodes, Det and N
o connect each Det and each N to the NP node that immediately dominates it
2. Increasing the generative power of phrase structure rules
 the generative capacity of phrase structure rules can be greatly increased
o by modifying the phrase structure rules in various natural ways to allow
for the production of other, related phrase structure types adding
additional items
 optional Adjective Phrases
o
modifying the NP rule to allow for adding an optional AdjP to
rule 2
NP  Det (AdjP) N
the little child
 in principle the number of AdjPs in the NP is unlimited
the chubby red-haired little child
o
adding another rule that specifies the structure of AdjPs
AdjP  Adj
 optional Adnominal Prepositional Phrases
o adding an optional PrepP to rule 2
NP  Det (AdjP) N (PrepP)
the child in the corner
the puppy with the black spot
the puppy [with the black spot] [over his left eye]
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3. Lexical insertion
 phrase structure rules generate the phrase structure tree, that is, they define
the nodes of the grammatical constituents
 at the next stage, the appropriate lexical items are inserted in nodes
 lexical insertion rules
o connect the output of the phrase structure rules – the phrase structure
tree - to the lexicon
o provide potential lexical items to occupy the nodes labeled by the parts of
speech
N: child, puppy, garden
Det: the
Vt: find
Prep: in
o assure that the cooccurrence restrictions applying to lexical items are
respected, restrictions such as the following
 the verb "find" ordinarily requires subjects that are animate
 the adjective "pregnant" is ordinarily applied to animate females
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