Linguis 3: Introduction to Linguistics
Winter 2019
Problem Set 4: Syntax
Due 2/15/2019. 91 points possible
1. For each pair of expressions below, say whether they belong to the same
syntactic category or not and give an example supporting your answer. You do
not have to say which syntactic category any of the expressions below belong
to---just say whether they are the same or different and give evidence. (3 points
each)
a. seemed happy
always seemed happy
b. loud bar
bar down the street
c. extremely loud bar
the bar
d. slept all day
liked
e. quickly
quite
f. walked
rode the bus
2. For each underlined expression below, say which syntactic category it belongs to and
give one piece of evidence supporting your answer. (3 points each)
a. Sally sent me a long annoying email.
b. Sally sent me a long annoying email.
c. Sally sent me a long annoying email.
d. Sally rides her bike fast.
e. Sally rides her bike fast.
f. The writing of her latest novel took more time than anticipated.
3. Draw a phrase structure tree for each of the following expressions. (5 points each)
a. thought Sally hated Bob.
b. barked yesterday
c. fell into the pond
d. drifted slowly under the bridge
e. this silly picture of Pat
f. Chris loved Robin passionately.
g. Pat pushed the stubborn horse into the barn.
f. A student from my class claimed the teacher disliked him.
4. Consider the following example which shows the order of NPs and prepositions in
Japanese PPs.
(1) kono kodomo
this child
"with this child"
to
with
(2) *to kono kodomo
a. Write a lexical entry for each word in the Japanese phrase in this example.
(5 points)
b. Write a phrase structure rule that allows the construction of PPs out of
prepositions and NPs in Japanese. (5 points)
c. Construct a phrase structure tree for the Japanese phrase sono hito to "with that
person". (5 points)
Introduction to Linguistics
Syntax I
Semantics:
How form relates
to meaning.
Syntax:
Structure of
sentences.
Morphology:
Structure of words
words..
Phonology:
Structure of sounds.
Phonetics:
How sounds are
articulated.
Basics
Syntax
•
•
Syntax is the study of the structure of sentences.
•
•
•
Phonemes combine to form morphemes.
Morphemes combine to form words.
Words combine to form sentences.
Not so simple…
A sentence expresses a complete meaning.
•
•
A phoneme has no meaning.
A morpheme is the smallest unit that expresses a
meaning.
From Phonemes to Sentences
•
•
•
Languages usually have around 25 different phonemes.
•
•
Around 10,000-50,000 different morphemes.
How many different sentences?
•
Unlimited.
The meaning of every morpheme must be memorized.
•
If you’ve never heard the morpheme wug before, you
can’t figure it out.
The meaning of every sentence is predictable given the
parts.
•
If you’ve never heard the sentence
My hovercraft is full of eels
before, you can still understand it.
Compositionality
•
Sentences follow the principle of compositionality: the
meaning of the whole is the meaning of the parts plus
how they are combined.
form
“the cat sat
on the mat”
meaning
Compositionality
•
Sentences follow the principle of compositionality: the
meaning of the whole is the meaning of the parts plus
how they are combined.
•
•
•
So, what are the parts?
•
Syntactic categories.
And what are the ways that they are combined?
•
Syntactic rules.
Of all the possible combinations of words, only a few form
meaningful sentences.
Grammar
•
In syntax, we categorize sequences of words as
grammatical or ungrammatical within a language.
•
A mental grammar is a speaker’s unconscious
knowledge of how a language works.
•
When you know a language, you know its rules:
Phonological rules, morphological processes, syntactic
rules, …
/t/
z
+/
-
/æ
_V
‘
/
]
ʰ
t
+/
>[
/-
d/
l
ra
m
or
/t
of
plu
>
to
[æ
̃]
fo
rm
/_
N
pa
st
SYNTACTIC RULES
te
ns
e
Grammar
•
A sentence is grammatical in a language if it follows the
rules in the mental grammar of that language.
•
A sentence is ungrammatical if it breaks those rules: that
is, if it is something that people would not say.
My hovercraft is full of eels.
✓
* Hovercraft of full eels my is. ✗
Prescriptive vs. Descriptive Grammar
•
When you learned “grammar” in school, you may have
learned things like:
• “Don’t end a sentence with a preposition”
•
•
•
•
“Don’t use passive voice”
“Don’t use less with a count noun, like less
customers. You should say fewer customers.”
This is prescriptive grammar: Someone’s ideas
about what makes for “correct” or good writing.
•
Not our business as scientists!
We’re interested in descriptive grammar: a
description of the rules people actually do follow in
normal language use.
Grammaticality
•
A sentence is grammatical in a language if it follows the
rules in the mental grammar of that language.
•
A sentence is ungrammatical if it breaks those rules: that
is, if it is something that people would not say.
•
In studying syntax we will rely on grammaticality
judgments: a speaker’s intuitive judgment about
whether a sentence is grammatical or not.
•
If a sentence is grammatical we also call it well-formed.
Syntax and Meaning
•
•
Grammaticality is separate from plausibility!
It doesn’t matter how nonsensical or false the meaning is,
all that matters is that it follows the rules of the language.
Colorless green ideas sleep furiously.
✓
Syntax and Meaning
•
•
Grammaticality is separate from plausibility!
It doesn’t matter how nonsensical or false the meaning is,
all that matters is that it follows the rules of the language.
✓
Green
sleep
colorless
furiously
ideas.
✗
*
Colorless green ideas sleep furiously.
Syntax and Meaning
•
•
Grammaticality is separate from plausibility!
It doesn’t matter how nonsensical or false the meaning is,
all that matters is that it follows the rules of the language.
I have a friend who is always full of ideas, good ideas and
bad ideas, fine ideas and crude ideas, old ideas and new
ideas. Before putting his new ideas into practice, he usually
sleeps over them to let them mature and ripen. However, when
he is in a hurry, he sometimes puts his ideas into practice
before they are quite ripe, in other words, while they are
still green. Some of his green ideas are quite lively and
colorful, but not always, some being quite plain and
colorless. When he remembers that some of his colorless ideas
are still too green to use, he will sleep over them, or let
them sleep, as he puts it. But some of those ideas may be
mutually conflicting and contradictory, and when they sleep
together in the same night they get into furious fights and
turn the sleep into a nightmare. Thus my friend often
complains that his colorless green ideas sleep furiously.
Syntax and Meaning
•
•
Grammaticality is separate from plausibility!
•
A sentence is grammatical when it is something
someone would say, no matter how unlikely the
context!
It doesn’t matter how nonsensical or false the meaning is,
all that matters is that it follows the rules of the language.
Grammaticality
I bought a dog.
✓
* Me bought a dog.
✗
Grammaticality
Sally ate an apple.
Sally ate a tree.
* Sally a tree ate.
* Sally ate an exploded.
✓
✓
✗
✗
Grammaticality
Sally likes Bob.
Bob likes Sally.
* Likes Sally Bob.
✓
✓
✗
Grammaticality
Sally will go to a store.
*
Sally has go to a store.
Sally has gone to a store.
*
Store a Sally gone to has.
✓
✗
✓
✗
Grammaticality
France is in Europe.
* France are in Europe.
France is in Africa.
✓
✗
✓
Grammaticality
This dog is mine.
*
This dog is my.
This is my dog.
*
This is mine dog.
✓
✗
✓
✗
Grammaticality
✓
Sally ate.
✓
Sally put the cup on the table. ✓
Sally put.
✗
*
Sally ate the food.
Syntactic Categories
Syntactic Category
•
How do we describe what makes some sequences of
words grammatical, and others ungrammatical?
•
The fundamental unit in syntax is the syntactic
category.
•
Preliminary definition: Two words are in the same
syntactic category iff you can interchange them in
every sentence without making the sentence
ungrammatical.
•
Alternatively: Two words are in different syntactic
categories iff you can find a sentence where
interchanging them makes a grammatical sentence
ungrammatical.
Syntactic Category
•
Example: Are cat and explode in the same syntactic
category?
•
•
•
1. Find a grammatical sentence containing cat.
•
I saw the cat.
✓
2. Try substituting explode instead of cat.
•
* I saw the explode. ✗
3. Therefore, cat and explode are in different
syntactic categories.
➡cat is a noun (N), explode is a verb (V).
Syntactic Category
•
Example: Are cat and mouse in the same syntactic
category?
•
•
•
•
1. Find a grammatical sentence containing cat.
•
I saw the cat.
✓
2. Try substituting mouse instead of cat.
•
I saw the mouse.
✓
3. Are there any examples where it doesn’t work?
4. If no examples, then they are in the same syntactic
category.
➡Both nouns (N).
Syntactic Category
•
Example: Are Mary and mouse in the same syntactic
category?
•
•
•
1. Find a grammatical sentence containing Mary.
•
Mary is my friend.
✓
2. Try substituting mouse instead of Mary.
•
* Mouse is my friend. ✗
3. The substitution made the sentence ungrammatical,
so they are in different syntactic categories.
Syntactic Category
•
Example: Are the and my in the same syntactic
category?
•
•
•
•
1. Find a grammatical sentence containing the.
•
Hand me the salt.
✓
2. Try substituting my instead of the.
•
Hand me my salt.
✓
3. Repeat the process. Are there any examples where it
doesn’t work?
4. None, so they are in the same category.
➡ Both determiners (Det).
Syntactic Category
•
Example: Are the and blue in the same syntactic category?
•
•
1. Find a grammatical sentence containing the.
•
I like the salt.
✓
2. Try substituting blue instead of the.
•
I like blue salt.
✓
•
3. Repeat the process. Are there any examples where it
doesn’t work?
•
How about the other way?
•
•
•
The blanket is blue.
* The blanket is the.
✓
✗
4. The substitution made the sentence ungrammatical, so
they are in different categories.
•
•
Blue is an adjective. (Adj)
The is a determiner. (Det)
Syntactic Category: Not Just Words
•
•
Syntactic categories cover more than just words!
•
Example: Are the cat and a dog in the same syntactic
category?
For any two sequences of words, if you can
interchange them in all sentences without making the
sentence ungrammatical, then they are in the same
syntactic category.
•
•
Start sentence: I think the cat is cute.
‣
I think a dog is cute.
✓
✓
For any sentence you can think of that contains the
cat, you can substitute a dog and it’s still grammatical.
Syntactic Category
•
A syntactic category consisting of a sequence of
words is called a phrase.
•
•
The cat and a dog are in the same category: both are
noun phrases (NP)
Better definition: Two words or phrases are in the same
syntactic category iff you can interchange them in
every sentence without making the sentence
ungrammatical.
Syntactic Category
•
Example: Are dog and the cat in the same syntactic
category?
•
•
•
1. Find a grammatical sentence containing dog.
•
I have a dog.
✓
2. Try substituting the cat instead of dog.
•
* I have a the cat. ✗
3. The substitution makes the sentence ungrammatical,
so they are not in the same syntactic category.
➡ Dog is a noun (N).
➡ The cat is a noun phrase (NP).
Some Common Syntactic Categories
•
•
•
•
•
•
•
Nouns (N): cat, dog, car, water, salt, …
•
Verb phrases (VP): Anything that you can substitute with
did so, do so, or does so.
•
Prepositional phrases (PP): Phrases like in the park
Verbs (V): goes, went, runs, ran, …
Adjectives (Adj): big, red, beautiful, angry, …
Adverbs (Adv): quickly, fast, well, unfortunately, …
Determiners (Det): a(n), the, this, that, those, my, your, …
Prepositions (P): in, of, at, from, by, …
Noun phrases (NP): Anything that can you can substitute
with a pronoun (he, she, it, him, her, they, them).
What is a sentence?
•
A sentence is a phrase that can appear in this context:
• Sally thinks that ___________________.
‣ Sally thinks that the cat is cute.
➡the cat is cute is a sentence.
‣ *Sally thinks that the cat.
➡The cat is not a sentence.
Syntactic Constraints
Syntactic Constraints
•
The goal of syntax is to figure out what are the rules that
make some combinations of words grammatical, and
others ungrammatical?
•
Two kinds of constraints on words in sentences:
•
•
Co-occurrence constraints
•
If you have one word somewhere in a sentence, you
must also have another word somewhere else in the
sentence.
Word order constraints:
•
Words must be placed in a certain order for a
sentence to be grammatical.
Co-Occurrence Constraints
Sally hasn’t read the book.
*
Sally hasn’t read the this book.
*
Sally hasn’t read three book.
*
Sally hasn’t read the.
Sally hasn’t read three books.
✓
✗
✗
✗
✓
Co-Occurrence Constraints
•
•
•
Sometimes a word requires the presence of another word.
• Sally hasn’t read the book.
• *Sally hasn’t read the.
➡A determiner (Det) requires a noun (N).
Sometimes a word rules out the presence of another
word.
• *Sally hasn’t read the this book.
➡A determiner (Det) rules out other determiners (Det).
Sometimes a word requires that another word be in a
certain morphological form.
• *Sally hasn’t read three book.
• Sally hasn’t read three books.
➡A number word (Num) requires a plural noun (plural N).
Word Order Constraints
Sally hasn’t read the book.
*
Sally hasn’t read book the.
Sally saw the book.
*
*
Saw Sally the book.
Sally the book saw.
✓
✗
✓
✗
✗
Word Order Constraints
•
Certain words are required to go before other words.
• Sally read the book.
• *Sally read book the.
➡“the” must go before a noun. (Det N)
• Sally saw the book.
• *Saw Sally the book.
➡ The subject of a verb must go before the verb (V).
• Certain words are required to go after other words.
• Sally saw the book.
• *Sally the book saw.
➡ The object of a verb must go after the verb (V).
• English has the order Subject—Verb—Object.
Introduction to Linguistics
Syntax II
Syntax So Far
•
•
Syntax is the study of the structure of sentences.
A sentence is grammatical in a language if it follows the
rules that you know implicitly as a speaker of that
language.
•
•
We’ve seen phonological and morphological rules.
What do syntactic rules look lile?
Words and sequences of words fall into syntactic
categories: if two words or sequences of words can be
substituted for each other in all sentences, then they are
in the same syntactic category.
Syntactic Category
•
Example: Are cat and mouse in the same syntactic
category?
•
•
•
•
1. Find a grammatical sentence containing cat.
•
I saw the cat.
✓
2. Try substituting mouse instead of cat.
•
I saw the mouse.
✓
3. Are there any examples where it doesn’t work?
4. If no examples, then they are in the same syntactic
category.
➡Both nouns (N).
Syntactic Category
•
Example: Are the and blue in the same syntactic
category?
•
•
•
1. Find a grammatical sentence containing the or blue.
•
The blanket is blue.
2. See what happen when you substitute the for blue.
•
* The blanket is the.
4. The substitution made the sentence ungrammatical,
so they are in different categories.
•
•
Blue is an adjective. (Adj)
The is a determiner. (Det)
Syntactic Category
•
Example: Are cat and the cat in the same syntactic
category?
•
•
•
1. Find a grammatical sentence containing cat or the cat.
•
I like the cat.
2. See what happen when you substitute the cat for cat.
•
*
I like the the cat.
3. Therefore they are in different categories.
• cat is a noun (N)
• The cat is a noun phrase (NP)
NP
Det
N
the cat
Syntactic Category
•
Example: Are cat and furry cat in the same syntactic
category?
•
•
•
1. Find a grammatical sentence containing cat or furry cat.
•
I like the furry cat.
2. See what happen when you substitute cat for furry cat.
•
I like the cat.
3. Are there any examples where it becomes
ungrammatical?
N
Adj
N
furry cat
Syntactic Category
•
Example: Are the furry cat and furry cat in the same
syntactic category?
•
•
•
1. Find a grammatical sentence containing the furry cat or
furry cat.
•
I like the furry cat.
2. See what happen when you substitute the furry cat for
furry cat.
•
*I like the the furry cat.
3. They are in different categories
•
•
NP
Noun (N)
vs. Noun Phrase (NP)
N
Det
Adj
N
I like the furry cat
Syntactic Constraints
Syntactic Constraints
•
The goal of syntax is to figure out what are the rules that
make some combinations of words grammatical, and
others ungrammatical?
•
Two kinds of constraints on words in sentences:
•
•
Co-occurrence constraints
•
If you have one word somewhere in a sentence, you
must also have another word somewhere else in the
sentence.
Word order constraints:
•
Words must be placed in a certain order for a
sentence to be grammatical.
Co-Occurrence Constraints
Sally hasn’t read the book.
*
Sally hasn’t read the this book.
*
Sally hasn’t read three book.
*
Sally hasn’t read the.
Sally hasn’t read three books.
✓
✗
✗
✗
✓
Co-Occurrence Constraints
•
•
•
Sometimes a word requires the presence of another word.
• Sally hasn’t read the book.
• *Sally hasn’t read the.
➡A determiner (Det) requires a noun (N).
Sometimes a word rules out the presence of another
word.
• *Sally hasn’t read the this book.
➡A determiner (Det) rules out other determiners (Det).
Sometimes a word requires that another word be in a
certain morphological form.
• *Sally hasn’t read three book.
• Sally hasn’t read three books.
➡A number word (Num) requires a plural noun (plural N).
Word Order Constraints
Sally hasn’t read the book.
*
Sally hasn’t read book the.
Sally saw the book.
*
*
Saw Sally the book.
Sally the book saw.
✓
✗
✓
✗
✗
Word Order Constraints
•
Certain words are required to go before other words.
• Sally read the book.
• *Sally read book the.
➡“the” must go before a noun. (Det N)
• Sally saw the book.
• *Saw Sally the book.
➡ The subject of a verb must go before the verb (V).
• Certain words are required to go after other words.
• Sally saw the book.
• *Sally the book saw.
➡ The object of a verb must go after the verb (V).
• English has the order Subject—Verb—Object.
Syntactic Rules
Syntactic Rules
•
A syntactic rule (also called a phrase structure rule)
states what words can form a syntactic category and
in what order.
NP
Det
the
N
cat
NP → Det N
The category noun phrase
can consist of
A determiner followed by a noun
Syntactic Rules
•
A syntactic rule (also called a phrase structure rule)
states what words can form a syntactic category and
in what order.
•
A syntactic rule that spells out the individual words in
a category is called a lexical entry.
N → cat
Lexical entries
for the
category N
N → mouse
N → dog
N → person
Syntactic Rules
•
A syntactic rule (also called a phrase structure rule)
states what words can form a syntactic category and
in what order.
•
A syntactic rule that spells out the individual words in
a category is called a lexical entry.
N → cat, mouse, dog, person, …
Lexical entries
for the
category N
Syntactic Rules
•
A syntactic rule (also called a phrase structure rule)
states what words can form a syntactic category and
in what order.
•
A syntactic rule that spells out the individual words in
a category is called a lexical entry.
N → cat, mouse, dog, person, …
Det → the, a(n), this, that, my, your, …
Adj → big, blue, small, furry, cute, …
Recursive Rules
•
A syntactic rule (also called a phrase structure rule)
states what words can form a syntactic category and
in what order.
N
Adj
N
furry cat
N → Adj N
The category noun
can consist of
An adjective followed by a noun
Recursive Rules
•
A syntactic rule (also called a phrase structure rule)
states what words can form a syntactic category and
in what order.
•
A syntactic rule can be recursive: it has the same
category on the left hand side and the right hand side.
N → Adj N
N
N
N
Adj
N
furry cat
Adj
Adj
N
small furry cat
Rules So Far
NP → Det N
N → Adj N
N → cat, mouse, dog, person, …
Det → the, a(n), this, that, my, your, his, her, their, …
Adj → big, blue, small, furry, cute, …
NP
N
Det
Adj
N
the furry cat
Figuring Out Rules
•
So what are the syntactic rules covering the rest of the
sentence?
Sally saw the cute cat.
*
Sally saw cute cat.
Sally saw NP.
___.
✓
✗
Figuring Out Rules
Sally saw the cute cat.
Sally liked the cute cat.
*
•
Sally slept the cute cat.
Sally slept.
✓
✓
✗
✓
The verbs saw and liked are in a different syntactic
category from slept.
• We call saw and liked transitive verbs (TV)
•
•
They must be followed by an object NP.
We call slept an intransitive verb (V).
• It cannot be followed by an object NP.
Figuring Out Rules
•
Let’s write a rule to describe the fact that transitive
verbs must be followed by an object NP.
•
•
•
We’ll call the containing category verb phrase (VP).
And we’ll have a rule for the intransitive verbs too.
And we need lexical entries for TV and V.
VP
?? → TV NP
VP → V
V → slept, ran, cried, jumped, …
TV → liked, saw, punched, learned, …
Verb Phrases
VP → TV NP
VP → V
NP → Det N
N → Adj N
V → slept, ran, cried, jumped, …
TV → liked, saw, punched, learned, …
Det → the, a(n), this, that, my, your, his, her, their, …
Adj → big, blue, small, furry, cute, …
N → cat, mouse, dog, person, …
Sally VP.
Verb Phrases
VP → TV NP
VP → V
NP → Det N
NP → PropN
N → Adj N
V → slept, ran, cried, jumped, …
TV → liked, saw, punched, learned, …
Det → the, a(n), this, that, my, your, his, her, their, …
Adj → big, blue, small, furry, cute, …
N → cat, mouse, dog, person, …
PropN → any name
Sally VP.
Sentence Rule
•
The rule describing a sentence is:
S → NP VP
•
A sentence consists of a (subject) noun phrase
(NP) followed by a verb phrase (VP).
S
VP
NP
NP
PropN
TV
Det
N
Sally saw the mouse
Ditransitive Verbs
Sally liked Bob.
Sally gave Bob the book.
*
Sally
liked
Bob
the
book.
*
Sally gave Bob.
✓
✓
✗
✗
VP → DTV NP NP
DTV → gave, sent, handed, emailed, …
Sentential Verbs
Sally thought Bob liked the cat.
*
Sally thought Bob.
Sally punched Bob.
* Sally punched Bob liked the cat.
✓
✗
✓
✗
VP → SV S
SV → thought, said, discovered, …
Rules So Far
S
VP
VP
VP
VP
→
→
→
→
→
NP VP
V
TV NP
DTV NP NP
SV S
NP → Det N
NP → PropN
N → Adj N
VP → VP Adv
V → slept, ran, cried, jumped, …
TV → liked, saw, punched, learned, …
DTV → gave, sent, handed, emailed, …
SV → thought, said, discovered, …
Det
Adj
N
PropN
Adv
→ the, a(n), this, that, my, your, his, her, their, …
→ big, blue, small, furry, cute, …
→ cat, mouse, dog, person, …
→ any name
→ well, furiously, calmly, quickly, badly, …
Prepositional Phrases
The cat in the house chased the mouse.
✓
PP → P NP
P → in, on, to, of, above, from, about, …
N → N PP
•
A PP can attach to a noun.
• It modifies the meaning of the noun.
Prepositional Phrases
The cat in the house chased the mouse.
The cat slept in the house.
✓
✓
PP → P NP
P → in, on, to, of, above, from, about, …
N → N PP
VP → VP PP
•
A PP can also attach to a verb phrase.
Syntactic Rules for English
S
VP
VP
VP
VP
VP
VP
→
→
→
→
→
→
→
NP VP
V
TV NP
DTV NP NP
SV S
VP Adv
VP PP
NP → Det N
NP → PropN
N → Adj N
N → N PP
PP → P NP
Introduction to Linguistics
Syntax III
Syntax So Far
•
•
Syntax is the study of the structure of sentences.
•
There are two kinds of constraints on grammatical
sentences in any language:
A sentence is grammatical in a language if it follows the
rules that you know implicitly as a speaker of that
language.
•
•
Co-occurrence constraints
Word order constraints
Syntax So Far
•
We capture the syntactic constraints of a language using
syntactic rules (also called phrase structure rules).
S → NP VP
The category Sentence
•
can consist of
A noun phrase
followed by a verb phrase
Rules that specify individual words for a syntactic
category are called lexical entries:
N → cat, mouse, dog, person, …
Det → the, a(n), this, that, my, your, his, her, their, …
Adj → big, blue, small, furry, cute, …
Syntax So Far
S
VP
VP
VP
VP
VP
VP
→
→
→
→
→
→
→
NP VP
V
TV NP
DTV NP NP
SV S
VP Adv
VP PP
NP → Det N
NP → PropN
N → Adj N
N → N PP
PP → P NP
V → slept, ran, cried, jumped, …
TV → liked, saw, punched, learned, …
DTV → gave, sent, handed, emailed, …
SV → thought, said, discovered, …
…
p. 232
Generation and Parsing
•
You can apply the rules in two ways:
•
Generation: Start with S and randomly choose which
rules to follow until you have generated a sentence.
•
•
The rules should be made so that you can
generate all and only the grammatical sentences
of a language.
Parsing: Start with a sentence and figure out how it
could have been generated by the rules.
•
Draw a phrase structure tree for the sentence.
Generation Example
S → NP VP
VP → V
VP → TV NP
VP → DTV NP NP
VP → SV S
NP → Det N
NP → PropN
N → Adj N
N → N PP
S
NP
VP
PP → P NP
VP → VP Adv
VP → VP PP
V → slept, ran, cried, jumped, …
TV → liked, saw, punched, learned, …
Det
N
that person
VP Adv
V
badly
DTV → gave, sent, handed, emailed, …
SV → thought, said, discovered, …
Det → the, a(n), this, that, my, your, his, her, their, …
slept
Adj → big, blue, small, furry, cute, …
N → cat, mouse, dog, person, …
Adv → well, furiously, calmly, quickly, badly, …
Parsing Example
S
S → NP VP
VP → V
VP → TV NP
NP
VP
VP → DTV NP NP
S
VP → SV S
VP → VP Adv
NP
VP → VP PP
VP
NP → Det N
NP → PropN
N → Adj N
NP
N → N PP
N
PP → P NP
PropN
SV
Det
N
TV
Det
Adj
N
Sally thought the dog chased the furry cat.
How to Parse a Sentence
S → NP VP
VP → V
VP → TV NP
VP → DTV NP NP
•
1. Label the categories for all the
individual words.
•
2. Find a sequence of categories that
matches the right hand side of a rule,
and which haven’t yet been matched
with any rule.
•
3. Draw a tree with the left hand side of
the rule on top.
•
4. Repeat until you have a single tree that
covers all the words in the sentence.
VP → SV S
VP → VP Adv
VP → VP PP
NP → Det N
NP → PropN
N → Adj N
N → N PP
PP → P NP
Some Useful Tests
•
•
For whether something is a VP: Can you substitute did so,
does so, or do so?
•
Bob saw Mary on the street.
•
Bob thought Mary slept badly in her bed.
➡Bob did so.
➡Bob thought Mary did so.
For whether something is an NP: Can you substitute a
single proper name (PropN)?
•
Sally liked the cute gray cat.
•
Sally liked the cute gray cat.
➡Sally liked Bob.
➡*Sally liked the Bob.
Lexical Ambiguity
More on Transitive vs. Intransitive Verbs
Sally devoured the cake.
*
Sally
slept
the
cake.
*
Sally devoured.
Sally slept.
Sally ate the cake.
Sally ate.
TV → devoured
V → slept
✓
✗
✗
✓
✓
✓
TV → ate
V → ate
More on Transitive vs. Intransitive Verbs
TV → ate
•
•
•
V → ate
The word ate belongs to two different syntactic
categories!
• It could be a transitive verb (TV) or an intransitive
verb (V).
Very many words belong to multiple syntactic
categories.
•
This situation is called lexical ambiguity.
Another example: this can be either a determiner
(Det) or a pronoun (Pro)
Det → this
Pro → this
Lexical Ambiguity
N → love
•
•
We love Bob.
Our love for Bob.
N → present
•
•
TV → love
Adj → present
The present situation is dangerous.
Bob gave me a cool present.
Structural Ambiguity
Structural Ambiguity
S
VP
VP
VP
VP
→
→
→
→
→
NP VP
V
TV NP
DTV NP NP
SV S
VP → VP Adv
VP → VP PP
NP → Det N
NP → PropN
N → Adj N
N → N PP
PP → P NP
Structural Ambiguity
•
•
Structural ambiguity means that the same sequence of
words has multiple different parse trees.
•
The different parse trees correspond to different
interpretations.
•
The examples we’ve seen are PP attachment
ambiguities.
Very many naturally-occurring sentences have some
structural ambiguity!
Structural Ambiguity
Structural Ambiguity
Structural Ambiguity
•
•
•
•
ENRAGED COW INJURES FARMER WITH AX
•
SQUAD HELPS DOG BITE VICTIM
BRITISH LEFT WAFFLES ON FALKLAND ISLANDS
STOLEN PAINTING FOUND BY TREE
TWO SISTERS REUNITED AFTER 18 YEARS IN
CHECKOUT COUNTER
How to Parse a Sentence
S → NP VP
VP → V
VP → TV NP
VP → DTV NP NP
VP → SV S
•
1. Label the categories for all the
individual words.
•
2. Find a sequence of categories that
matches the right hand side of a rule,
and which haven’t yet been matched
with any rule.
•
3. Draw a tree with the left hand side of
the rule on top.
•
4. Repeat until you have a single tree that
covers all the words in the sentence.
VP → VP Adv
VP → VP PP
NP → Det N
NP → PropN
N → Adj N
N → N PP
PP → P NP
Introduction to Linguistics
Syntax IV
Semantics:
How form relates
to meaning.
Syntax:
Structure of
sentences.
Morphology:
Structure of words.
Phonology:
Structure of sounds.
Phonetics:
How sounds are
articulated.
Basics
Syntax So Far
•
•
Syntax is the study of the structure of sentences.
•
There are two kinds of constraints on grammatical
sentences in any language:
A sentence is grammatical in a language if it follows the
rules that you know implicitly as a speaker of that
language.
•
•
•
Co-occurrence constraints
Word order constraints
We capture the syntactic constraints of a language using
syntactic rules (also called phrase structure rules).
S → NP VP
Ambiguity
•
Certain syntactic rules create ambiguity.
•
•
Lexical ambiguity is when there are multiple lexical
entries for a single word.
•
•
TV → love
N → love
Structural ambiguity is when there are multiple ways
to generate or parse a single string of words.
•
The enraged cow attacked the farmer with an ax.
How to Parse a Sentence
S → NP VP
VP → V
VP → TV NP
VP → DTV NP NP
VP → SV S
•
1. Label the categories for all the
individual words.
•
2. Find a sequence of categories that
matches the right hand side of a rule,
and which haven’t yet been matched
with any rule.
•
3. Draw a tree with the left hand side of
the rule on top.
•
4. Repeat until you have a single tree that
covers all the words in the sentence.
VP → VP Adv
VP → VP PP
NP → Det N
NP → PropN
N → Adj N
N → N PP
PP → P NP
Syntactic Analysis
Syntactic Analysis
S → NP VP
VP → V
VP → TV NP
VP → DTV NP NP
VP → SV S
VP → VP Adv
VP → VP PP
NP → Det N
NP → PropN
N → Adj N
N → N PP
PP → P NP
•
The goal of syntactic analysis is to
write down syntactic rules that
generates all and only the grammatical
sentences in a language.
•
If there is a grammatical sentence
not generated by the rules, then we
say the rules undergenerate.
•
If your rules generate sentences that
are not grammatical, then we say
your rules overgenerate.
S → NP VP
VP → V
VP → TV NP
Kinds of Nouns
VP → DTV NP NP
Sally liked the book.
VP → SV S
VP → VP Adv
VP → VP PP
NP → Det N
NP → PropN
N → Adj N
N → N PP
*
Sally liked book.
Sally liked the wine.
Sally liked wine.
✓
✗
✓
✓
PP → P NP
NP → MassN
MassN → water, cake, food, wine, …
Syntactic Analysis
•
•
The goal of syntactic analysis is to write down
syntactic rules that generates all and only the
grammatical sentences in a language.
•
If there is a grammatical sentence not generated by
the rules, then we say the rules undergenerate.
•
If your rules generate sentences that are not
grammatical, then we say your rules overgenerate.
The solution to undergeneration is usually to add more
rules.
Pronouns
S → NP VP
VP → V
VP → TV NP
NP → Pro
Pro → I, you, he, she, me, him, her, …
S
VP → DTV NP NP
VP → SV S
VP → VP Adv
VP → VP PP
NP → Det N
NP → PropN
N → Adj N
N → N PP
PP → P NP
NP
VP
Pro
TV
NP
he
saw
Pro
he
Pronouns
ProSubj → I, he, she, we, they
ProObj → me, him, her, us, them
Pro → you, it, this, that
NPSubj → ProSubj
NPSubj → Pro
NP → ProObj
NP → Pro
S → NPSubj VP
Pronouns
S
ProSubj → I, he, she, we, they
ProObj → me, him, her, us, them
Pro → you, it, this, that
NPSubj → ProSubj
NPSubj → Pro
NPSubj
VP
ProSubj
TV
NP
he
saw
ProObj
NP → ProObj
NP → Pro
S → NPSubj VP
him
Syntactic Analysis
•
The goal of syntactic analysis is to write down
syntactic rules that generates all and only the
grammatical sentences in a language.
•
If there is a grammatical sentence not generated by
the rules, then we say the rules undergenerate.
•
If your rules generate sentences that are not
grammatical, then we say your rules overgenerate.
•
The solution to undergeneration is usually to add more
rules.
•
The solution to overgeneration is usually to make rules
and categories more specific.
Agreement
✓
The student likes the book. ✓
The
student
like
the
book.
✗
*
The students liked the book. ✓
The students like the book. ✓
The
students
likes
the
book.
✗
*
The student liked the book.
Patterns in Syntactic
Rules
Patterns in Syntactic Rules
VP
VP
VP
VP
→
→
→
→
• Many rules have a common
V
structure:
TV NP
• XP → … some kind of X …
DTV NP NP • Inside each phrase, there is a
single core word called the
SV S
NP → Det N
NP → PropN
PP → P NP
head of the phrase.
•
The head expresses the
most important idea of the
phrase.
Patterns in Syntactic Rules
•
VP → VP Adv
VP → VP PP
N → Adj N
N → N PP
Other rules do not specify a head,
but instead expand a category
recursively with some added
categories.
• X→…X…
• These are called adjunction rules.
• The added categories are called
adjuncts.
Types of Rules
•
There are a few types of syntactic rule:
VP → TV NP
•
Head rules expand a phrase into a
head plus other material.
VP → VP Adv
•
Adjunction rules expand a category
into itself plus other material.
S → NP VP
•
Exocentric rules expand a category
into other categories of different types.
Types of Rules
•
Most rules are head-final or head-initial:
•
A head-final rule puts the head at the end of the phrase:
NP → Det N
•
A head-initial rule puts the head at the beginning of the
phrase:
VP → DTV NP NP
VP → VP Adv
Types of Rules
•
Most rules in English are head-initial: so we say English is a
head-initial language.
•
Other languages are head-final: most of their rules are
head-final.
•
Japanese, Korean, Tamil, Telugu, …
Parsing in a Head-Final Language
English Rules
Japanese Rules (approximately)
S → NP VP
VP → V
VP → TV NP
S → NP VP
VP → V
VP → NP TV
VP → DTV NP NP
VP → NP NP DTV
VP → SV S
VP → S SV
VP → VP Adv
VP → Adv VP
VP → VP PP
VP → PP VP
NP → Det N
NP → PropN
N → Adj N
NP → Det N
NP → PropN
N → Adj N
N → N PP
N → PP N
PP → P NP
PP → NP P
NP → N
Head-Initial vs. Head-Final Languages
•
Most languages are heavily tilted towards being mostly headfinal or mostly head-initial.
Languages with the rule VP → TV NP and the rule PP → P NP
Languages with the rule VP → NP TV and the rule PP → NP P
Languages with the rule VP → TV NP and the rule PP → NP P
Languages with the rule VP → NP TV and the rule PP → P NP
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