1. Today Phrase structure rules, trees Constituents Recursion Conjunction
Readings: 6.4 – 6.5

2. Phrase structure (review)
1) Every word belongs to a lexical category
2) Lexical categories forms heads of phrases
3) How phrases are formed is governed by rules (= ‘phrase structure rules’)
Head (of a phrase): The constituent fundamental to the phrase, from which the phrase derives its name. (e.g. a noun phrase is “headed” by a noun

3. 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

4. Phrase structure rules
General schema:
X  Y Z
“X consists of Y followed by Z”

5. Phrase structure rules
Noun 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 N
Det Adj N
Det N PP
The head of the phrase is obligatory.
(where ‘()’ indicates optionality)

6. Phrase structure trees
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
A tree diagram labeled with phrasal categories that shows structure of phrases, sentences.
Node: A labeled branch point in a phrase structure tree.

7. Prepositional phrase (PP)in
from a boy in a bubble
Phrase structure rule for PPs:
PP  P (NP) P
P NP

8. Phrase structure trees
PP PP
P P NP
in from Det N PP
a boy P NP
in Det N
a bubble
A tree diagram labeled with phrasal categories that shows structure of phrases, sentences.
Node: A labeled branch point in a phrase structure tree.

9. 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)

10. the cat on the mat in the house on the streetNP
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

11. Verb phrase (VP) Phrase structure rule for VPs: VP  V (NP) (PP) (Adv)
sang
ate the cake
ate the cake hungrily
sang a song in the shower
fell into the pond slowly
Phrase structure rule for VPs:
VP  V (NP) (PP) (Adv) V
V NP
V NP Adv
V NP PP
V PP Adv

12. sang ate Det N sang Det N P NP badly the cake a song in Det N
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

13. Structural ambiguity
discuss [sex with Dr. Ruth] [discuss sex] with Dr. Ruth

14. Structural ambiguity
discuss [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

15. Sentences Must contain an NP and a VP May contain an auxiliary verb
The dog barked.
*The dog.
*Barked.
May contain an auxiliary verb
The dog will bark.
S  NP (Aux) VP

16. S
NP VP
Det N V NP
The dog ate Det N
the bone
S  NP VP

17. S
NP Aux VP
Det N will V NP
The dog eat Det N
the bone
S  NP Aux VP

18. Conjunction
Words and phrases of the same category can be combined using conjunctions (and, but, or)
Cats and dogs make good pets.
Eat, drink, or be merry.
You can lead a horse to water but you can’t make him drink.
NP  NP conj NP
VP  VP conj VP 
S  S conj S
X  X conj X

19. Conjoined phrases NP NP  NP Conj NP NP Conj NP NP  Det N Det N Det N
the
cat
and
the
dog

20. Conjoined sentences I 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