Transcript Midterm Exam Nov. 2 1pm to 4pm • Room: 3002 NSH • Open book – But no internet or cell phone • • • • May bring food. May step.

Midterm Exam Nov. 2
1pm to 4pm
• Room: 3002 NSH
• Open book
– But no internet or cell phone
•
•
•
•
May bring food.
May step outside to smoke.
May go to restrooms.
May ask questions.
Summary: Parts of Speech
• Claim:
– Parts of speech can be defined by
• Distribution – where they appear
• Morphology – which prefixes, suffixes, etc apply to them
• Each criterion of distribution or morphology is
called a test.
• Methodology
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Identify relevant tests
Apply tests
Judge grammaticality
Interpret results
Annotation
• The Test methodology is state of the art for
annotation projects, including many
treebanking projects.
Trees and Constituents
Grammars and Lexicons
11-721
September 10, 2007
Phrasal Categories
Sentence
Verb Phrase
Prepositional Phrase
Noun Phrase
Det Noun Modal Verb
Adjective Phrase
Noun Phrase
Adverb Adjective Prep. Det Noun
This boy must seem incredibly stupid to
that girl.
Phrasal Categories
• NP: Noun Phrase
• VP: Verb Phrase
• PP: Prepositional Phrase
• AP: Adjective Phrase
• AdvP: Adverb Phrase
• S: Sentence
Tree Terminology
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Mother
Daughter
Sister
Dominate
Immediately Dominate
Node (branching or non-branching)
Branch
Terminal Node/Leaf Node
Phrasal Nodes (non-terminal)
Lexical Nodes (pre-terminal)
Constituent
• A constituent is a string of words such that
there is one node that dominates those
words and no other words.
S
Tree 1
VP
PP
NP
NP
N
V
P
Sam climbed
Det
up
the ladder.
S
Tree 2
VP
NP
N
NP
V
V
Sam picked
P
up
N
Det
N
the ladder.
Discussion
• What are the constituents of Tree 1 and Tree
2?
• Which strings of words are constituents in
one tree but not the other?
Coordination as a diagnostic test
for constituency
• To test whether a string of words s1 is a
constituent, conjoin it using and with
another string which
– Is an uncontroversial constituent of the same
category as s1 or
– (If you don’t have a hypothesis about the
category of s1), has the same part of speech
sequence as s1
Applying the coordination test
• Sam climbed [up the ladder] and [out the
window].
• *Sam picked [up a ladder] and [out some
new boots].
Movement as a test for constituency
• A constituent might appear in different
positions in a sentence, but stay in one
piece.
• There are different movement rules that
affect different constituents (NP, PP, AP,
VP).
Begin side track for some extra
background
Transformational Grammar and
Movement Rules
S
NP
S
Meaning preserving
tree-to-tree mapping
NP
VP
VP
The chocolate V
The kids V
ate
NP
PP
was eaten by the kids
the chocolate
Surface Structure
Deep Structure
Transformational Grammar
1.
2.
3.
4.
Sentences that mean the same thing have the same deep
structure.
Tree-to-tree mappings convert deep structure trees into
surface structure trees.
Tree-to-tree mappings must be meaning preserving, so
that (1) remains true.
Government and Binding Theory and the Minimalist
Program (Chomsky) are theories that characterize which
tree-to-tree mappings are meaning preserving.
1.
2.
3.
The kids ate the chocolate.
The chocolate was eaten by the kids. (meaning preserving)
The chocolate ate the kids. (not meaning preserving)
Non-Transformational Grammar
• In this class, we will not use transformational
grammar.
• There will be no tree-to-tree mappings. (There
will be other kinds of mappings.)
• The canonical representation of meaning will
not be a deep structure tree.
• There will be a different way to connect
sentences that mean the same thing.
Movement is still a useful metaphor
at this stage in the course
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Sam climbed up a ladder.
Up a ladder Sam climbed up a ladder.
Sam likes chocolate.
It is chocolate that Sam likes chocolate.
End side track
To use movement as a test for
constituency
• First, identify a meaning preserving
movement rule (tree-to-tree mapping).
• Give an example showing this movement
rule applying to an uncontroversial
example:
– Sam ran into the room.
– Into the room Sam ran.
Applying the movement test
• Then apply the same rule to a controversial
example that you want to test.
• Sam climbed up a ladder.
• Up a ladder Sam climbed. passes the test
• Sam Picked up a ladder.
• *Up a ladder Sam picked. fails the test
Another movement rule
• Identify a meaning preserving movement rule and
illustrate it with a non-controversial example:
– He ran into the room.
– It was into the room that he ran.
• Apply the movement rule to the controversial
examples that you want to test.
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He climbed up a ladder.
It was up a ladder that he climbed. passes the test
He picked up a ladder.
*It was up a ladder that he picked. fails the test
Be sure that you are testing the right thing
• Are these sentences relevant in showing Tree 1
and Tree 2 have different structures?
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It was a ladder that Sam climbed up.
It was a ladder that Sam picked up.
Sam climbed up a ladder and a wall.
Sam picked up a ladder and a rope.
?*A ladder was climbed up by Sam.
A ladder was picked up by Sam.
A ladder he climbed up.
A ladder he picked up.
Discussion
• Test each sentence with coordination and
movement tests for Tree 1 and Tree 2.
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I took out the garbage.
I turned off the light.
I turned off the highway.
I fell off my bike.
I looked up the number.
Constituency of Verb Phrases
A class participation exercise
(based on Radford, Chapter 3, exercise IX)
• Goals of the exercise:
– Relying on tests when your intuition fails
– Adapting to inconsistent results
• (e.g., find evidence for disqualifying some of the tests)
• The five trees on the following slide have all been proposed by
linguists, in published articles, for the sentence: He has been writing a
letter.
• Unlike the previous exercise with particles and PPs, people do not
have good intuitions about which structure is correct.
• We will learn several more tests for constituency, and apply them to
these sentences in order to pick one of the trees as the correct one.
• The answer comes out different every year (depending on
grammaticality judgments and creativity in finding evidence for
disqualifying some tests).
S
S
TREE 1
TREE 2
VP
AUX
V
NP PERF PROG V
AUX
He has
NP PERF PROG V
He has
V
He
has
TREE 4
VP
AUX
V
VP
V
VP
V
NP
VP
AUX
NP
V
He
has been writing a letter.
He
has
TREE 5
VP
V
VP
NP
been writing a letter.
S
NP
been writing a letter.
S
TREE 3
VP
NP
NP
been writing a letter.
S
VP
V
NP
been writing a letter.
NP
Test 3: Deletion
• A constituent can be deleted, if you can identify
an appropriate meaning-preserving deletion
rule.
Verb Phrase Deletion
• A meaning preserving deletion rule for VP
(verb phrases):
– John was writing a letter and Bill was writing a letter too.
– John was writing a letter and Bill was writing a letter too.
– John was writing a letter and Bill was too.
• Condition: you need to leave behind an auxiliary
verb or insert do if there was no auxiliary verb.
– John wrote a letter and Bill wrote a letter too.
– John wrote a letter and Bill did too.
Note to myself. Feel free to read it.
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John wrote a letter and Bill too.
Stripping, not verb phrase deletion.
Sam likes chocolate, and vanilla too.
Sam likes chocolate and Sam likes vanilla too.
Looks like a non-constituent was deleted (so it’s
not left-peripheral ellipsis either).
• It is still a test for constituency because the piece
left behind has to be a constituent (I think).
Test 4: Pro-Forms
• A pronoun can substitute for a noun:
– Sam went to school.
– He went to school.
• Other pro-forms can substitute for other
parts of speech.
A Pro-VP: Do so
• Put do in the same form as the verb you are
substituting it for.
– The English verb forms are base, present, past, present
participle, and past participle.
• John wrote a letter and Bill wrote a letter too.
• John wrote a letter and Bill did so too.
– Write and do are in the past tense.
• John was singing and Bill was singing too.
• John was singing and Bill was doing so too.
– Sing and doing are present participles.
A meaning-preserving movement rule
for VPs
– I thought he was singing and he was singing.
– I thought he was singing and singing he was singing.
– I thought he was singing and singing he was.
• Like Verb Phrase Deletion, this movement rule must
leave an auxiliary verb behind. If there is no auxiliary
verb, insert do as an auxiliary verb.
– I thought he would sing a song and he did sing a song.
– I thought he would sing a song and sing a song he did.
Test 5: Adverb Placement
• Sentence Adverb:
• Probably he can rely on my
support.
• He probably can rely on my
support.
• He can probably rely on my
support.
• ?He can rely probably on
my support.
• ?He can rely on my support
probably.
• VP Adverb:
• *Completely he can rely
on my support.
• *He completely can rely
on my support.
• He can completely rely on
my support.
• He can rely completely on
my support.
• He can rely on my support
completely.
Adverb placement
• Sentence adverbs must be immediately
dominated by a node labeled S.
• VP adverbs must be immediately dominated
by a node labeled VP.
Non-Constituent Coordination
• John found the letter and Bill signed the
letter.
• John found the letter and Bill signed the
letter.
S
NP
John
VP
V
NP
Det N
found
the letter
Non-Constituent Coordination
• I gave a book to Mary and gave a letter to
Sue.
• I gave a book to Mary and gave a letter to
Sue.
S
VP
NP
V
I
gave
NP
a book
PP
to Mary
Right Node Raising
• If you conjoin two strings of words that
have identical final constituents, delete the
first instance of the identical constituent.
• John found the letter and Bill signed the
letter.
Left Peripheral Ellipsis
• If you conjoin two strings of words that
have identical initial constituents, delete the
second instance of the identical constituent.
• I gave a book to Mary and gave a letter to
Sue.