Transcript PowerPoint

CAS LX 522
Syntax I
Class 1a.
Introduction to the enterprise
Some things we know
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Is this English?
The cat slept.
 Slept the cat.
 Cat slept the.
 Cat the slept.
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Why?
The task
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What do we know?
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Try to generalize.
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The comes before cat, cat comes before slept.
Slept is the verb, maybe this holds of all verbs.
The cat is the subject, maybe this holds of all subjects.
Subjects contain the and a noun, with the first.
An English sentence has a subject followed by a verb.
Formalize (make precise)
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Nouns: cat, dog
Verbs: slept, yawned
[Sentence [Subject the Noun ] Verb ]
The task
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Check:
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[Sentence [Subject the Noun ] Verb ]
The cat slept.
The dog yawned.
The cat yawned.
The dog slept.
Look at further data (predictions):
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The cat chased the dog.
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This is an English sentence, but our schema cannot produce
it. Our “theory of English sentences” is insufficient. We need
to revise/extend it.
The task
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Consider the counterexample (or the class
of counterexamples) to understand where
the current theory falls short.
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The cat chased the dog.
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The dog is probably the same kind of thing as the cat, but we
don’t want to call it a “subject” (it’s traditionally called the
“object”).
It contains the and a noun, and the noun seems to be the
most important part.
Since it contains more than one word, we can call it a
“phrase”—it’s not a whole sentence, but it’s more than a
word.
So, we’ll call it a “noun phrase.”
The task
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Consider the counterexample (or the class
of counterexamples) to understand where
the current theory falls short.
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The cat chased the dog.
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In this English sentence, there is a noun phrase both before
and after the verb. So, in addition to our previous schema,
we add a second one.
Theory of English sentences:
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[Sentence [NP the Noun ] Verb ]
[Sentence [NP the Noun ] Verb [NP the Noun ] ]
Lather, rinse, repeat
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And the process continues.
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The cat chased a dog.
A cat chased the dog.
A cat chased a dog.
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It looks like a NP can either have the or a as its first element.
Thus:
Theory of English sentences:
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[Sentence [NP the Noun ] Verb ]
[Sentence [NP a Noun ] Verb ]
[Sentence [NP the Noun ] Verb [NP the Noun ] ]
[Sentence [NP the Noun ] Verb [NP a Noun ] ]
[Sentence [NP a Noun ] Verb [NP the Noun ] ]
[Sentence [NP the Noun ] Verb [NP a Noun ] ]
Generalizing
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What we’ve ended up with is a bit clumsy,
but we can now generalize our schemas to
make this more compact:
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[NP the Noun ]
[NP a Noun ]
[Sentence NP Verb ]
[Sentence NP Verb NP]
 Not only does this reduce the amount we have to write down,
but it actually makes a more profound prediction: If this much
of our theory of English sentences is right, then anything that
can be a noun phrase subject can also be a noun phrase
object. This is not just making our notation more compact,
but it is a substantive addition to the theory.
Compacting the notation
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There are some further ways we can
consolidate our theory of English sentences
by using some common notational tools.
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X is optional: (X)
Either Y or Z: {Y/Z}
Thus:
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[Sentence NP Verb (NP) ]
[NP {the/a} Noun ]
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Unlike our introduction of a separate schema for NP, this
change is not a substantive change to our theory of English
sentences, it is just a shorthand for the same theory.
The grumpy cat
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As a demonstration of the benefit of
introducing a separate NP schema,
consider:
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The grumpy cat chased the unhappy dog.
How can we extend our theory of English
sentences to allow for this sentence? What
other word sequences are predicted to be
English sentences? Are they?
Now, what are we doing?
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Ok, so we have the beginnings of a theory of
English sentences. But what is it?
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As we’ve developed it, it is a description of sentences of English,
what we might need if we wanted to program a computer to produce
English sentences.
But it is also a subset of what English speakers
know about English.
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You may or may not have previously thought about the fact that
subjects precede verbs and objects follow verbs (or the analog in
your native language), but you knew it nevertheless. You could
identify sequences of words that did not have this property as not
being part of your language, but it’s tacit knowledge. As such, we
have to study this knowledge indirectly, based on what are judged to
be valid sentences and what aren’t.
What English speakers
know about English
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An English speaker has a complex system of
knowledge that allows him/her to distinguish
between sentences of English and nonsentences of English. We’ll refer to this
system as a grammar. At its simplest, a
grammar is a means of deciding whether a
sequence of words is grammatical (e.g., a
sentence of English) or not. We’re studying
the properties of that system.
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It’s not always obvious what it is that is wrong with nonsentences, but still the judgments (intuitions) are clear.
Types of (un)acceptability
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*Big that under staple run the jump swim.
*The dog are snoring.
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My toothbrush is pregnant again.
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These are ungrammatical—there is a problem with their
form, they are not English. We write * to indicate this.
This is nonsensical, given our knowledge about the world
(not about English), but it is grammatical.
As I knitted the sock
The horse raced
fell to the floor.
past the barn fell.
The rat the cat the dog chased caught escaped
adeptly.
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These are interestingly difficult to parse but once you “get
it,” they are fine (if clumsy) sentences of English.
Parentheses and optionality
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In describing data, people will often use the (), {}
shorthand notation to indicate optionality or
options:
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Pat (quickly) ran to the bank.
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Pat washed the asparagus.
*Pat washed quickly the asparagus.
The dish ran away with *(the) spoon.
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Pat quickly ran to the bank.
Pat washed (*quickly) the asparagus.
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Pat ran to the bank.
The dish ran away with the spoon.
*The dish ran away with spoon.
The cat chased {a/the} dog.
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The cat chased a dog.The cat chased the dog.
Ambiguity and stars
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Sentences can be ambiguous.
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I sat by the bank.
Sometimes we might have reason to expect
ambiguity that is not there, which is also
indicated using *, on a disambiguating
continuation.
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How did John say Mary fixed the car?
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With a wrench.
In a high-pitched voice.
How did John ask if Mary fixed the car?
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*With a wrench.
In a high-pitched voice.
Knowledge of language is
actually really complicated
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Bill told her mother that Mary is a genius.
Bill told her that Mary is a genius.
I told Mary that Pat gave a book to me.
Who did I tell that Pat gave a book to me?
*Who did I tell Mary that gave a book to me?
Who did I tell Mary that Pat gave a book to?
I loaned Mary the book Pat gave me.
Who did I loan the book Pat gave me?
*Who did I loan Mary the book gave me?
*Who did I loan Mary the book Pat gave?
How do people know this?
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All native speakers of English know this.
Little kids weren’t told these rules (or
punished for violating them)…
“You can’t question a subject in a
complement embedded with that”
 “You can’t use a proper name as an object if
the subject is co-referential.”
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Two questions
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What do people know about their
language?
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Including things we know “unconsciously”
How do people come to know it?
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Tricky question for things that we don’t know
we know.
Systematicity
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What people eventually end up with is a
system with which they can produce (and
rate) sentences. A grammar.
Even if you’ve never heard these before, you
know which one is “English” and which one
isn’t:
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Eight very lazy elephants drank brandy.
Eight elephants very lazy brandy drank,
Kids say wugs.
Positive and negative evidence
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Adults know if a given sentence S is
grammatical or ungrammatical. This is part
of the knowledge kids gain through
language acquisition.
Kids hear grammatical sentences
(positive evidence)
Kids are not generally told which sentences
are ungrammatical
(no negative evidence)
Positive and negative evidence
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One of the striking things about child
language is how few errors they actually
make.
For negative feedback to work, the kids
have to make the errors (so that it can get
the negative response).
But they don’t make the errors.
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(Kids do make errors, but not of the kind that one
might expect if they were just trying to extract
patterns from the language data they hear)
Poverty of the stimulus
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What is the next number in this sequence?
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1, 2, 3, __
How do you form a yes-no question?
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Pat will leave.
Will Pat leave?
The book that you were reading was good.
*Book the that you were reading was good?
*Were the book that you reading was good?
Was the book that you were reading good?
The “Language instinct”
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The linguistic capacity is part of being
human.
Like having two arms, ten fingers, a vision
system, humans have a language faculty.
The language faculty (tightly) constrains
what kinds of languages a child can learn.
=“Universal Grammar” (UG).
But languages differ
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English, French: Subject Verb Object (SVO)
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Japanese, Korean: Subject Object Verb (SOV)
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John ate an apple.
Pierre a mangé une pomme.
Taroo-wa ringo-o tabeta.
Chelswu-ka sakwa-lul mekessta.
Irish, Arabic (VSO), Malagasy (VOS), …
But languages differ
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English: Adverbs before verbs
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Mary quickly eats an apple.
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(also: Mary ate an apple quickly)
*Mary eats quickly an apple.
French: Adverbs after verbs
Geneviève mange rapidement une pomme.
 *Geneviève rapidement mange une pomme.
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Parameters
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We can categorize languages in terms of
their word order: SVO, SOV, VSO.
This is a parameter by which languages differ.
The dominant formal theory of first language
acquisition holds that children have access to
a set of parameters by which languages can
differ; acquisition is the process of setting
those parameters.
What are the parameters?
What are the “universal” principles of
grammar?
The enterprise
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The data we will primarily be concerned with
are native speaker intuitions.
Native speakers, faced with a sentence S,
know whether the sentence S is part of their
language or isn’t. These intuitions are highly
systematic.
We want to uncover the system (which is
unconscious knowledge) behind the
intuitions of native speakers—their
knowledge of language.
I-language
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We are studying the system behind one
person’s pattern of intuitions.
Speakers growing up in the same community
have very similar knowledge, but language is
an individual thing (“I-language”).
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One doesn’t need to ask the académie française whether
Geneviève rapidement mange une pomme is a sentence of
French. One knows.
I-languages of a community is can be
characterized, but it is external to the speaker
(“E-language”), not any one person’s
knowledge, a generalization over many
people’s I-languages.
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For example, Parisian French.
Competence
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We are also concerned with what a person
knows—what characterizes a person’s
language competence. We are in general
not concerned here with how a person ends
up using this knowledge (performance).
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You still have your language competence when you are
sleeping, in the absence of any performance. Being
drunk doesn’t make one think “bought some John
coffee” is English, though perhaps one might say it.
Prescriptive rules
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Another thing we need to be cautious
of are prescriptive rules. Often
prescriptive rules of “good grammar”
turn out to be impositions on our native
grammar which run counter to our
native competence.
After all, why did they need to be rules
in the first place?
Prescriptive rules
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Prepositions are things you don’t end a
sentence with.
It is important to religiously avoid splitting
infinitives.
Remember: Capitalize the first word after a
colon.
Don’t be so immodest as to say I and John
left; say John and I left instead.
Impact is not a verb.
The book which you just bought is offensive.
Prescriptive rules
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When making grammaticality judgments (or
when asking others to make grammaticality
judgments), we must do our best to factor
out prescriptive rules (learned explicitly, e.g.,
in school).
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We’re not interested in studying the prescriptive
rules; we could just look them up, and it isn’t likely to
tell us anything deep about the makeup of the human
mind. They’re really just a “secret handshake,”
allowing educated people to detect one another.
Syntax as science
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Syntax, as practiced here, is a scientific
enterprise. This means, in particular,
approaching syntax using the scientific
method.
Step 1: Gather observations (data)
Step 2: Make generalizations
Step 3: Form hypotheses
Step 4: Test predictions made by these
hypotheses, returning to step 1.
Syntax as science
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This is pretty much the way other scientific
disciplines work… biology, chemistry, physics.
We may start out with a kind of “folk
understanding” of a field.
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For example, you push something and it moves. You
stop pushing, and it stops. The sun revolves around the
earth from East to West, followed by the moon. Water
is a basic element, like fire. Whales are very big fish,
like dolphins, or tuna, but bigger.
Ockham’s Razor: posit as few concepts and
relations as we can get away with. A leaner
theory is a better theory. A more easily
falsifiable theory is a better theory too.
Levels of adequacy
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If our hypotheses can predict the existence of
the grammatical sentences in a corpus (a set
of grammatical sentences), it is observationally
adequate.
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Note: the grammar described by “some number of words appear
in some order” is observationally adequate, for pretty much any
language. This is not a very difficult or satisfying level of
adequacy to reach. Nor is it disprovable, but it hasn’t really
advanced our understanding of the world.
If our hypotheses can predict the nativespeaker intuitions about which sentences are
grammatical and which are ungrammatical, it
is descriptively adequate.
Levels of adequacy
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If we can take a descriptively adequate set
of hypotheses one step further and account
not only for the native speaker judgments
but also for how children come to have
these judgments, our hypotheses are
explanatorily adequate.
It’s this last level that we are hoping to
achieve.
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Basic principles
Parameters of variation
How to set the parameters from child’s input
Infinite use of finite means
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English has an infinite number of sentences. Any
natural language does.
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John said that English has an infinite number of sentences.
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Mary said that John said that English has an infinite number of sentences.
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Pat said that Mary said that John said that English has an infinite number of sentences.
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Tracy said that Pat said that Mary said that John said that English has an infinite number of sentences.
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Chris said that Tracy said that Pat said that Mary said that John said that English has an infinite number of sentences.
If S is a sentence and N is a name,
N said that S is also a sentence.
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S  N said that S
Some of the earliest work in grammatical theory
was done by trying to state rules of this form, the
goal being to generate the sentences of a
language.
Of the past and the future
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Serious scientific study of sentence
structure of this kind generally began in
the 50’s, driven to a large extent by
the work of Noam Chomsky.
It’s now half a century later, and we
have learned a lot about how syntax
works.
Of the past and the future
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Progress was incremental, and often
required revising our assumptions about how
sentences are really put together.
Data was examined, generalizations were
arrived at, hypotheses were formed,
predictions were tested—and often led to
revisions of the generalizations and the
hypotheses, and so forth.
Of the past and the future
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Two goals of the class:
Think like a syntactician.
 Be able to read (relatively recent) books,
articles, etc. about syntax.
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It’s not really enough to just know what
people concluded, we need to
understand why they concluded what
they did.
Some milestones
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Until about the mid-70’s, phrase structure
rules.
S  NP VP
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VP  V (NP)
Mid-70’s, X-Bar Theory (a generalization
about what are possible PSRs).
In the 80’s, a fairly significant shift to
Government and Binding Theory (viewing
grammar a little less like a computer
program). Very productive.
In the 90’s, another shift to the Minimalist
Program (an attempt at simplification, as
well as a change in philosophy).
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