Upload
rick-mckinnon
View
3.084
Download
2
Embed Size (px)
Citation preview
Knowledge of Syntax
Phrase Structure Grammars
Intuitions About Grammaticality
• Syntax – a system whose primitive terms are non-
semantic and non-discourse derived and whose principles of combination make no reference to system external factors.
Autonomy of Syntax
• Syntax and Semantics are independent.• The structure of language is
autonomous from the meaning.– “Colorless green ideas sleep furiously.”– Compare:
a.“Furiously sleep ideas green colorless.”b.“Revolutionary new ideas occur infrequently.”
Autonomy of Syntaxa. He is likely going to be late.b. He is probably going to be late.
c. He is likely to be lated. *He is probably to be late.
e. He allowed the rope to go slack.f. *He let the rope to go slack.
g. He isn’t sufficiently tall.h. *He isn’t enough tall.
Autonomy of Syntax
• We all share a strong sense as speakers of English that these sentences are ill formed, but that they are also clearly interpretable. So whatever it is that lets us know that they are structurally flawed is autonomous from whatever it is that let's us understand their intended meaning.
Autonomy of Syntax
• Sometimes sentences have two meanings, leading us to believe that they must have two structures.
• Ambiguous sentences:– Kate saw the man with the telescope– Visiting relatives can be tedious.– The President gave the Chinese dolls.
Trees in Syntax
• The lines in the trees are branches.• The end of any branch is a node.• M is the root node (no branches above it)• N is the mother of D, E, and F.• D, E, F, H, I, and J are terminal nodes (no branches below them).
M
N
D E F
O
H I J
Trees in Syntax
• Syntactic trees are just a graphical variant of labeled brackets.
N
D E F
= [N D E F ]N
Dominance is another way of expressing inclusion in a set.
Phrasal Structure
• Consider: Kate saw the man with the telescope. • It’s pretty intuitive that the telescope is a
linguistic unit:
the telescope
art noun
NP
What did Kate see the man with?
Phrasal Structure
• The basic idea is that the is classified as an article, and telescope is a noun, and the entire thing is a Noun Phrase.
the telescope
art noun
NP This is a constituent
Phrasal Structure
• Let’s take a slightly larger unit:
the telescope
art N
NP
with
PP
P
This is a Prepositional Phrase (PP), with the preposition with (P). The constituent the telescope is contained within the PP.
How did Kate see the man?
Phrasal Structure
• Continuing to build up the structure:
the telescope
art N
NP
with
PP
P
the man
Nart
NP
NP
Who did Kate see?
Phrasal Structure• Continuing up:
the telescope
art N
NP
with
PP
P
the man
Nart
NP
NP
saw
V
VP What did Kate do?
Phrasal Structure
the telescope
art N
NP
with
PP
P
the man
Nart
NP
NP
saw
V
VP
Kate
N
NP
S
“Kate saw the man carrying a telescope.”
Constituent
Phrasal Structure
the telescope
art N
NP
with
PP
P
the man
Nart
NP
saw
V
VP
Kate
N
NP
S
“Kate used a telescope to see the man.”
No constituent that dominates only the man with the telescope.
Memory
• I said that Markov Grammars have no ability to explain dependencies that are non-local:– The dog sleeps.– The dogs sleep.
• Subject-verb agreement. But what about: – The dog in the kennel sleeps.
Phrasal Structure
the kennel
art N
NP
in
PP
P
the dog
Nart
NPsing
NP
sleeps
V
VPsing
S
Phrasal Structure
the kennel
art N
NP
in
PP
P
the dogs
Nart
NPpl
NP
sleep
V
VPpl
S
Phrase Structure Rules
• The sentence (clause):1. S NP VP
• This rule says that every sentence consists of a noun phrase (NP) and a verb phrase (VP).
• Rule (1) corresponds to the traditional notion of subject and predicate.
Exercise
– This is a novel.– He feels empty.– So that was that.– Unfair’s unfair.– Nat was Nat.
– Work was his life.– Creators are workaholics.– Music was my refuge.– Space was the real
problem.– I was all humility.
Tufte, pp. 10-13
• Divide these short sentences into NP and VP:
This is a novel.
isThis
NP
N V
VP
S
a novel
N
NP
art
He feels empty.
feelsHe
NP
N V
VP
S
empty
AP
Adj
Creators are workaholics.
areCreators
NP
N V
VP
S
workaholics
NP
N
Exercise
• Draw trees for the following sentences:– Nat was Nat.– Work was his life.– Music was my refuge.– I was all humility.
A Question
• Why do we group the V with the second NP in the sentence? What’s the evidence for that?
• Constituency tests: NP V never acts as a unit.– What did he do? Feel empty. (Question)– What did empty? *He feel.– It was feel empty that he was. (Cleft)– *It was he feel that (was) empty.
Productivity
• We are able to make infinitely long sentences.
• Markov Grammars gave us a way to do that:
dog
dogs
snores
snore
The old● ●
●
●
●●
very
Productivity
• Different kinds of productivity:– The very, very, very, …, old dog snores.– The dog that chased the cat that ate the
rat…– I believe that you know that she thinks that
they doubt…– The apple on the table in the house on the
street in the town by the lake in the country on the planet…
Trees and Rules
N
NP
art
= N art N
Trees and Rules
• We’ve seen trees that represent the following set of rules:
1. S NP VP2. N art N3. VP V NP4. VP V AdjP5. AdjP Adj6. VP V NP PP7. PP P NP
Exercise
• Draw the Phrase Structure tree that is defined by the PS rules below:
1. S NP VP2. NP Art N3. VP V NP PP4. NP Art N5. PP P NP6. NP Art N
• Be sure to apply the rules in order (1-6).
Lexicon
• The terminal nodes can be replaced with lexical items:– Nouns = cat, dog, ice cream, bananas, avocados– Verbs = like(s), eat(s), – Art = a, the, my, this, that, one, all– P = in, on, at, under, with
• Add lexical items to your tree structure.
Exercise
• Consider the following sentences:– Space was the real problem.– War remains the decisive human failure.– The myth of war creates a new, artificial
reality.• What rule are we missing to account for
these sentences?
NP Art Adj N
wasSpace
NP
N V
VP
S
real
NP
AdjArt N
the problem
Phrase Structure Rules• Productivity in a PS grammar comes from
the ability of rules to combine into an infinite sequence:1. NP NP PP2. PP P NP NP
NP PP
P NP
NP PP
P NP …
Phrase Structure Rules
• This can apply to different types of rules:1. S NP VP2. VP V S S
NP VP
V S
NP VP
V S …
Exercise
• What rules would you use to account for this type of productivity?– The dog that chased the cat that ate the
rat…
More Ambiguities
• Draw phrase structure trees for the following ambiguous sentences:– Visiting relatives can be tedious.– The President gave the Chinese dolls.– The hungry bear fishes.