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Today Phrase structure rules, trees

Constituents

Recursion Conjunction

Readings: 6.4 6.5

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Phrase structure (review)1) Every word belongs to a lexicalcategory

2) Lexical categories forms heads of

phrases

3) How phrases are formed is governed by

rules (= phrase structure rules)

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Phrase structure rules Rules that determine

what goes into a phrase (constituents)

how the constituents are ordered

Constituent: a word or group of words

that function as a unit and can make up

larger grammatical units

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Phrase structure rules General schema:

X Y Z

X consists of Y followed by Z

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Phrase structure rulesNoun phrase (NP)

John

the boy a little boy

a boy in a bubble

Phrase structure rule for NPs:

NP (Det) (Adj) N (PP)

N

Det NDet Adj N

Det N PP

(where () indicates optionality)

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NP NP NP NP

N Det N Det Adj N Det N PP

John the boy a little boy a boy P NP

in Det N

a bubble

Phrase structure trees

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Prepositional phrase (PP) in

from a boy in a bubble

Phrase structure rule for PPs:

PPP (NP)

P

P NP

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PP PP

P P NP

in from Det N PP

a boy P NP

in Det N

a bubble

Phrase structure trees

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Recursion Some phrasal categories may appear to the left

or right of the arrow

NP (Det) N (PP)PP P (NP)

Recursion: the property of language that allows

for the embedding of categories (which can

yield infinitely long phrases)

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NP

Det N PP

the cat P NP

on Det N PP

the mat P NP

in Det N PP

the house P NP

on Det N

the street

the cat on the mat in the house on the street

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Verb phrase (VP) sang

ate the cake

ate the cake hungrily sang a song in the shower

fell into the pond slowly

Phrase structure rule for VPs:

VPV (NP) (PP) (Adv)

V

V NP

V NP AdvV NP PP

V PP Adv

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VP VP VP

V V NP V NP PP Adv

sang ate Det N sang Det N P NP badly

the cake a song in Det N

the shower

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Structural ambiguitydiscuss [sex with Dr. Ruth] [discuss sex] with Dr. Ruth

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Structural ambiguitydiscuss [sex with Dr. Ruth] [discuss sex] with Dr. Ruth

VP VP

V NP V NP PP

discuss N PP discuss sex P NP

sex P NP with Dr. Ruth

with Dr. Ruth

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Sentences Must contain an NP and a VP

The dog barked.

*The dog.*Barked.

May contain an auxiliary verb

The dog will bark.

S NP (Aux) VP

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S

NP VP

Det N V NP

The dog ate Det N

the bone

S NP VP

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S

NP Aux VP

Det N will V NP

The dog eat Det N

the bone

S NP Aux VP

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Conjoined sentencesI bought a book, but I returned it.

S S S conj S

S conj S S NP VP

NP VP but NP VP

I V NP I V NP

bought a book returned it