Transcript Meeting 3 Constituency, Trees, and Rules

Meeting 3
Syntax
Constituency, Trees, and Rules
Siti Mukminatun
Constituent
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Syntax is about the study of sentence structure.
(1) The students loved their syntax assignments.
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The statement that sentence (1) consists of a linear
string of words misses several important generalizations
about the internal structure of sentences and how these
structures are represented in our minds.
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In fact, the words in sentence (1) are grouped into units
(called constituents) and that these constituents are
grouped into larger constituents.
Constituent
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The notion that the and student are closely related to one
another is captured by the fact that they are as part of a
bigger unit that contains them, but not other words.
There are two different ways to represent this bigger unit.
One of them is to put square brackets around units.
[the student]
The other is to represent the units with a group of lines called
a tree structure:
the student
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These bigger units are called constituents.
Constituent
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Constituent: A group of words that functions
together as a unit.
Constituency is the most important and basic
notion in syntactic theory.
The “relatedness” is captured by membership in
a constituent.
Constituents don’t float out in space. Instead
they are embedded one inside another to form
larger and larger constituents. This is
hierarchical Structure
Constituent
TP
NP
D
The
VP
N
V
student loved
D
his
NP
AdjP
N
assignments
A
Syntax
Constituent
The child found the puppy
the child
the
child
found the puppy
found
the puppy
the
puppy
constituent
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Various linguistic tests reveal the constituent of a
sentence.
E.g. the set of words that can be used to answer a
question is a constituent.
“what did you find?”, the speaker might answer
“the puppy, not “found the”.
Pronouns can also substitute for natural groups.
In answer to the question “where did you find the
puppy? A speaker may answer “I found him in the
park”
Rules and Trees
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In generative grammar, generalizations about
structure are represented by rules. These rules
are said to “generate” the tree.
The rules are called phrase structure rules
(PSRs) because they generate the phrase
structure tree of a sentence.
A tree diagram with syntactic category
information is called a phrase structure tree
(constituent structure tree).
Phrase Structure Tree
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Three aspects of a speaker’s syntactic knowledge
are represented in phrase structure trees:
1. the linear order of the words in the sentence
2. the groupings of word into syntactic categories
3. the hierarchical structure of the syntactic
categories (e.g. sentence is composed of a NP
followed by a Verb Phrase is composed of a Verb
that may be followed by a NP, and so on.
Noun Phrase
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The simplest NPs contain only a noun (usually a proper noun
[+proper], pronoun [+pron], mass noun [−count] or a plural noun
[+plural]). (John, water, cats)
Our rule must minimally generate NPs then that contain only an N.
The format for PSRs is shown below. We use X, Y, and Z here as
variables to stand for any category.
XP
→
XYZ
the label
“consists of”
the elements that make up
for the constituent
the constituent
NP → N
This rule says that an NP is composed of (written as →) an N.
NP
N
Noun Phrases
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There are many NPs (e.g., those that are [+count]) that
are more complex than this of course:
a) the box
b) his binder
c) that pink fluffy cushion
NP → D N
This generates a tree like:
NP
D
the
N
box
Noun Phrase
NP → (D) N
Nouns can also be optionally modified by adjectives.
the big box
his yellow binder
 NP → (D) (AdjP) N
 Nouns can also take prepositional phrase (PP) modifiers
the big box of crayons
his yellow binder with the red stripe
 NP → (D) (AdjP) N (PP)
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Noun Phrases
D
the
NP
AdjP
big
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N
PP1
book
of poems
The NP constituent consists of four sub-constituents:D,
AdjP, N and PP.
Noun Phrases
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The [AdjP big] [AdjP yellow] box [PP of cookies] [PP with
the pink lid].
NP → (D) (AdjP+) N (PP+)
Adjective Phrases (AdjPs)
and Adverb Phrases (AdvPs)
the very yellow book
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This phrase has only one [very yellow] constituent
modifying N.
This constituent is called an adjective phrase (adjP)
AdjP → (AdvP) Adj
AdjP
AdvP
Adv
very
Adj
Yellow
Adjective Phrases (AdjPs)
and Adverb Phrases (AdvPs)
NP
D
the
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AdjP
Adj
big
the big yellow book
AdjP
Adj
yellow
N
book
Adjective Phrases (AdjPs)
and Adverb Phrases (AdvPs)
NP
D
AdjP
N
book
the
AdvP
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Adv
Very
the very yellow book
Adj
yellow
Adjective Phrases (AdjPs)
and Adverb Phrases (AdvPs)
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Principle of Modification (informal): Modifiers
are always attached within the phrase they
modify.
The adverb very modifies yellow, so it is part of
the yellow AdjP.
In “the big yellow book” by contrast, big doesn’t
modify yellow, it modifies book, so it is attached
directly to the NP containing book.
Adverb Phrases (AdvPs)
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A very similar rule is used to introduce AdvPs:
AdvP → (AdvP) Adv
very quickly
Adv P
Adv P
adv
very
Adv
quickly
Head
The head of a phrase is the word that gives the phrase
its category.
 E.g. the head of NP is the N, the head of a PP is the P,
the head of the AdjP is Adj and the head of AdvP is Adv.
AdjP
AdvP
head
head
AdvP
Adj
AdvP
Adv
Head
yellow
Head
quickly
Adv
Adv
very
very
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If we take the AdjP to be the mother then its
daughters are the AdvP and the head Adj.
Since AdvP and Adj are both daughters of
the same mother then we say they are
sisters.
Prepositional Phrases (PPs)
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Most PPs take the form of a preposition (the head)
followed by an NP:
a) [PP to [NP the store]]
b) [PP with [NP an axe]]
c) [PP behind [NP the rubber tree]]
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The PP rule appears to be: PP → P NP
In the rule, the NP in the PP is obligatory.
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Prepositional Phrase (PPs)
PP
P
NP
an
axe
Verb Phrases (VPs)
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the category headed by the verb: the verb phrase (VP).
Minimally a VP consists of a single verb. This is the
case of intransitives (V[NP __]):
VP → V
Amanda [VP left].
VP
V
Left
Verb Phrases
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Verbs may be modified by adverbs (AdvPs), which are, of course,
optional:
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Amanda [VP left quickly].
VP → V (AdvP)
VP
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V
left
AdvP
Adv
quickly
Verb Phrases
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Interestingly, many of these adverbs can appear on
either side of the V, and you can have as many AdvPs
as you like:
Amanda [VP quickly left].
Amanda [VP [AdvP deliberately] [AdvP always] left
[AdvP quietly] [AdvP early]].
VP → (AdvP+) V (AdvP+)
Verb Phrases
VP
AdvP
AdvP V
left
Adv
Adv
deliberately always
AdvP
AdvP
Adv
quietly
Adv
early
Verb Phrases
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VP → (AP+) V (NP) (AP+)
Bill [VP frequently kissed his mother-inlaw].
Bill [VP kissed his mother-in-law quietly].
(cf. *Bill [VP kissed quietly his mother-inlaw].)
Verb Phrases
VP
V
kissed
D
his
NP
AdvP
N
A
mother-in-law quietly
Verb Phrases
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It is also possible to have two NPs in a sentence, for
example with a double object verb like spare (V[NP __
NP NP]). Both these NPs must come between the verb
and any AdvPs:
I spared [NP the student] [NP any embarrassment]
[AdvP yesterday].
VP → (AP+) V (NP) (NP) (AP+)
Verb Phrases
VP
V
spare
D
The
NP
NP
N D
student any
AdvP
N
embarrassment
Adv
yesterday
Verb Phrases
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Verbs can be modified by PPs as well.
These PPs can be arguments as in
ditransitive verbs of the type V[NP __ NP
PP] (e.g., the PP argument of the verb put)
or they can be simple modifiers PP like for
a dollar below.
These PPs can appear either after an
adverb or before it.
Verb Phrases
a) Bill [VPfrequently got his buckets [PP from
the store ] [PP for a dollar]].
b) VP → (AdvP+) V (NP) (NP) (AdvP+) (PP+)
(AdvP+)
Verb Phrases
VP
AdvP
V NP
got
Adv
D
frequently his
PP
N
P
buckets from
PP
NP
D
the
P
for
N
store
NP
D
a
N
dollar
Clauses
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A clause consists of a subject NP and a VP.
The label we use for clause is TP.
[TP[NP Bill ] [VP frequently got his buckets
from the store for a dollar]].
This can be represented by the rule in
TP → NP VP
Verb Phrases
TP
NP
VP
N
Bill
AdvP
V
NP
PP
got
A
D
N
P
frequently his buckets from
D
the
PP
NP
P
for
N
store
NP
D
a
N
dollar
Clauses
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TPs can also include other items, including
unsurprisingly elements of the category T (such
as modal verbs and auxiliary verbs).
a) Cedric might crash the longboat.
b) Gustaf has crashed the semi-truck.
we won’t treat these as verbs, the reason for this
will become clear in later chapters. Note that the T
in the TP is optional.
TP → NP (T) VP
Clauses
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A tree showing the application of this rule
TP
NP
N
Cedric
T
might
VP
V
crash
NP
D
the
N
longboat
Clauses
Clauses don’t always have to stand on their own. There
are times when one clause is embedded inside another:
 [TP Shawn said [TP he decked the janitor]].
 The clause he decked the janitor, lies inside the larger
main clause. Often embedded clauses are introduced
by a complementizer like that or if:
 [TP Shawn said [CP [C that ] [TP he decked the
janitor]]].
 We need a special rule to introduce complementizers
(C):
a) CP → (C) TP
Tree (see p. 74)
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TP
NP
N
Shawn
VP
V
said
CP
C
that
NP
N
he
TP
VP
V
decked
NP
D
the
N
janitor
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All embedded clauses are CPs, whether or not they have
a complementizer. This means that a sentence like
Shawn said he decked the janitor will have a CP it even
though there is no complementizer that.

Embedded clauses appear in a variety of positions. The
embedded clause appears in essentially the same slot as
the direct object.
Embedded clause as direct object
TP
NP
N
Shawn
VP
V
said
CP
TP
NP
N
he
VP
V
decked
NP
D
the
N
janitor
Embedded clauses in subject
position
TP
CP
C
VP
TP
that
worried
VP
NP
N
he
V
V
N
NP
decked
D
the
NP
N
janitor
TP  { NP/CP} (T) VP
[TP [CP That he decked the janitor] worried Jeff].
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The last revision we have to make to our
PSRs is to add the CP as a modifier to NPs
to account for cases like:
NP  (D) (AdjP+) N (PP+) (CP)
TP
NP
D
The
N
fact
P
about
VP
PP
CP
NP
N
Bill
C
that
V
brothers
TP
NP
VP
N
he
V
likes
NP
natasha
NP
N
icecream
Relative Clauses
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In addition to the CPs that modify Ns, there is another kind of CP
modifier to an N. These are called relative clauses.
E.g. The man (whose car I hit __ last week) sued me.
The underscore in the sentence indicates where the gap is_ the
object of the verb “hit” is in the wrong place, it should be where the
underscore is. The corresponding to the gap we also have the whword “whose” and the noun ‘car”. These are appearing at the
beginning of the clause.
Relative clause actually appear in a different position than the CPs
that follow nouns like the fact.
It has to do with the relative position of the CP and the PP in the NP
rule.
Summary
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CP  (C) TP
TP  {NP/CP} (T) VP
HOW TO DRAW A TREE
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Bottom-up Trees
The Top-down Method of Drawing Trees
Bottom-up tress
1. Write out the sentence and identify the parts of speech:
D
Adv Adj N V
D
N
The very small boy kissed the platypus.
2. Identify what modifies what. Remember the modification relations. If the
word modifies something then it is contained in the same constituentas that
thing.
Very modifies small. V
ery small modifies boy.
The modifies boy.
The modifies platypus.
 The platypus modifies kissed.
 3. Start linking together items that modify one another. It often helps to
 start at the right edge. Always start with adjacent words. If the modifier
 is modifying a noun, then the rule you must apply is the NP rule:
Summary
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CP → (C) TP
TP → {NP/CP} (T) VP
VP → (AdvP+) V (NP)({NP/CP}) (AdvP+) (PP+)
(AdvP+)
NP → (D) (AdjP+) N (PP+) (CP)
PP → P (NP)
AdjP → (AdvP) Adj
AdvP → (AdvP) Adv