Unification grammar
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Transcript of Unification grammar
Unification Grammar
Trying to solve the same problems
Phrase structure rules
Transformational Grammar has PSRs
But it also needs features
And features may move
Or be copied
Transformational Grammars ALSO need MOVEMENT
Movement
PSRs, features, and movement
Unification Grammars
No movement
Phrase Structure Rules -- yes
Movement -- no
Just structure-sharing
Structure-sharing MEANS unification
And VERY complicated information IN words!
It looks very complicated!
Attribute-value matrix
Head-driven Phrase Structure Grammar
HPSG
HPSG is the most popular Unification Grammar
Sign-Based Construction Grammar
Attribute-value matrix (AVM)
AVMs MODEL words
This is a model of a word
Complex and structured
Words have ATTRIBUTES
For example PHON
PHON is phonological or sound-related information
Nobody cares about PHON
Unless they’re PHONologists!
SYNSEM is an attribute
SYNSEM is the syntactic and semantic information
We DO care about SYNSEM
• She • CASE • Nom
• We• CASE• Nom
• You• CASE• No case
• You saw me• I saw you
• Me• CASE• Acc
• Accusative case• Must be an object (complement)• Object and complement is the same thing
• Them• CASE• Acc
• We saw them (good)• Them saw him (no good)• Saw wants an Acc complement
VALENCE features
• Also called SUBCATEGORIZATION• SUBCAT• SUBJ• COMPS• COMPS is just an object
Valence is what you want to attract
Forming bonds
Forget this – too difficult
Bonding
• You are looking for a boyfriend or girlfriend• But he/she must have a good job• Must make more than ¥10,000,000 a year• Must be a sports player• Must be good at using computers• Must not be the oldest child in his/her family• Otherwise, you cannot bond• Good luck
No good
Incompatible
Or maybe you want a pet
• Must not be a fish• Must not make any mess• Doesn’t cost very much to buy• Must be very cute• Must understand what you’re thinking• Must understand Japanese commands• Otherwise, you cannot bond• Good luck
Pochi
• A smelly dog• Makes a lot of mess• Not at all cute• Doesn’t understand anything• You are not compatible with Pochi
Language works a tiny bit differently
• A smelly dog• Makes a lot of mess• Not at all cute• Doesn’t understand anything• You are not compatible with Pochi
But generally the same
• A smelly dog• Makes a lot of mess• Not at all cute• Doesn’t understand anything• You are not compatible with Pochi
How about language?
• I saw you• That’s OK
• Saw• COMPS• <NP[acc]>• You• CASE• x
She
• CASE • Nominative• [nom]• Nominative case• What does that mean?• It just means it’s a subject
• She punched Taro (good)• Taro punched she (no good)
saw and him
After bonding
Saw him
Compatible
Congratulations!
What about “I saw he”?
• HE• CATEGORY• NP• PERSON• 3rd
• NUMBER• singular
What about “I saw he”?
• HE• PERSON• 3rd
• NUMBER• Singular• GENDER• Male
What about “I saw he”?
• HE• GENDER• Male• CASE• Nominative• Nom• Nominative – because it must be a subject
“Saw he” – what’s the problem?
Case cannot match
Incompatible
It will never work out between us
Goodbye
Saw us
• SAW• COMPS <• NP[acc]>
• US• CATEGORY• NP
Saw us
• Us• CASE• Accusative• PERSON• 2nd
• NUMBER• Plural
Saw US
• Us• Gender• x
Before bonding
Saw doesn’t care about PERSON, NUMBER, or GENDER
It looks promising
After bonding
And they lived happily ever after
How about x?
X isn’t important
saw
• SAW• CATEGORY• VERB• COMPS• NP• CASE• Acc
saw
• SAW• COMPS• NP• PERSON• X• NUMBER• X• GENDER• x
John
• CATEGORY• NP• CASE• X• John can be a subject or an object
(complement)
John
• PERSON• 3rd
• NUMBER• singular• GENDER• male
Before bonding
Looks very promising
SAW really wants an [acc] complement
SAW doesn’t care about anything else
John really wants to be 3rd, singular, male
John wants to be an NP
But John doesn’t care about CASE
After bonding
What a wonderful sharing relationship!
Bad sentences
• They saw we• We is nominative [nom] case
• saw• SUBJ< NP[nom]>• COMPS<NP[acc]>
We walks
• Walks• SUBJ<NP[nom]
PERSON 3rd
NUMBER singularGENDER >
Walks wants a 3rd person singular subject with Nominative case
We walks
• Walks• SUBJ<NP[nom]
PERSON 3rd
NUMBER singularGENDER >
• We is no good because it is 1st person plural.
How about these funny boxes?
Attribute value graphs
Forget about it for now
CATEGORY or CAT
CAT carries the syntactic features
She is a HEAD and a noun (noun phrase)
What kind of word is it?
[She] is a noun
HEAD attribute is noun
Nominative CASE
CONTENT and CONTEXT is the semantic info
[She] is 3rd person
[She] is singular
[She] is feminine
[She] CONTENT
• PER 3rd
• NUM sing• GEND fem
How about walks?
[walks][walks]
HEAD attribute is verb
[walks][walks]
[walks] has VALENCE attributes
[walks][walks]
VALENCE is also known as SUBCAT
[walks][walks]
VALENCE/SUBCAT who cares?
[walks][walks]
VALENCE sounds more scientific
[walks][walks]
VALENCE means attract or repel
[walks][walks]
[walks] attracts a noun
[walks][walks]
[walks] attracts a subject
[walks][walks]
[walks] specifies information about the subject
[walks][walks]
[walks] specifies information about CATEGORY and CONTENT
[walks][walks]
[walks]
SUBJ<CAT|HEAD noun|CASE nominative CONT [1] | PER 3rd
NUM singGEND >
CONT|walker [1]
CONT of subject matches in CONT of the verb
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND >
CONT|walker [1]
If the verb takes [she] as a subject …
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND >
CONT|walker [1]
CONT [1] matches CONT of [she]
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND >
CONT|walker [1]
If the verb takes [she] as a subject
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND >
CONT|walker [1]
Don’t worry about the details
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND >
CONT|walker [1]
It’s all the same matching
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND >
CONT|walker [1]
Structure sharing
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND >
CONT|walker [1]
Feature sharing
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND >
CONT|walker [1]
[She] CONTENT
• PER 3rd
• NUM sing• GEND fem
[She] CONTENT
• PER 3rd
• NUM sing• GEND fem
So when [walks] takes [she] …
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND x
CONT|walker [1]
This …
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND x
CONT|walker [1]
… becomes this
SUBJ<CAT|HEAD noun|CASE nominative CONT [1]|PER 3rd
NUM singGEND fem
CONT|walker [1]
[walks] VALENCE features and CONT features
Notice the structure-sharing
Usually marked with a number in a square
Why is it a number in a square?
Why not?
Who cares?
Could be a color
Or a funny shape – it doesn’t matter
If it really happens in our brains …
… what is it like?
The number in the square shows the structure-sharing
It shows the UNIFICATION
That’s it!
STRUCTURE A = [m _ t _ h]STRUCTURE B = [_ a _ c _]
Unify A and BWhat happens?A+B = [match]That’s it!
It looks complicated
STRUCTURE A = [s _ a _ e]STRUCTURE B = [_ h _ r _]
Unify A and BWhat happens?A+B = [share]But it’s basically very simple (and no movement)
Here’s some [walks] info again!
Notice the VALENCE specifications
[Walks] attracts a NP with nominative case
Walks attracts a NP with CONT [3rd,sing]
[she] has CASE nom
[she] has CONT 3rd, sing, fem
No problem
• She walks • That’s a good sentence
• What about this?• Her walks• Is that a good sentence?• No• Why?
Here’s [her]
[walks] attracts a NP[nom]
[her] is CASE acc (accusative)
The CONT of [her] is OK
But it is the wrong syntactic CATEGORY
Unification fails …
… if there is a mismatch
So don’t panic …
[walks][walks]
… when you see these complicated AVMs
[walks][walks]
It takes a bit of time …
[walks][walks]
You have to get used to it
[walks][walks]
But it’s basically very simple
[walks][walks]
And no movement
[walks][walks]
Don’t forget -- VALENCE features
[walks][walks]
VALENCE or SUBCAT
[walks][walks]
[walks] attracts a noun
[walks][walks]
1. What’s important to you?
• I don’t know• Must be good at cooking• Must be rich• Whatever
2. Unification grammars do not have …
• Movement• Movement operations
3. Unification Grammars rely on feature ….
• Sharing• Matching
• You could also say structure sharing
4. An attribute Value Matrix is a ….
• Model• A model of a word or phrase
Attribute Value Matrix
[walks][walks]
5. We• CAT• Noun, NP• CASE • Nominative, [nom], nom• PERSON• 1st• NUMBER• Plural• GENDER• x
6. US• CAT• NP• CASE• Accusative, [acc], acc• PERSON• 1st
• NUMBER• Plural• GENDER• x
JOHN
• CAT NP• CASE • x• PERSON• 3rd
• NUMBER• Singular• GENDER• Male
8. Walks
• CAT • Verb• SUBJ • NP case [nom],• CONT • 3rd
• Singular
9. ATE
• SUBJ• NP• Case [nom]• CONT x x• COMPS• NP• Case [acc]• CONT x x
GIVES
• CAT verb• SUBJ• NP case [nom]• CONT 3rd Singular
GIVES
• COMPS • NP case [acc]• CONT x, x• NP case [acc]• CONT x, x
CONTENT of gives
• CONTENT give• GIVER 1• GIVEN 2• GIFT 3
GIVES (Alternative)
• CAT• Verb• SUBJ• NP case [nom]• COMPS• NP case [acc] CONT x, x• PP case [dative] CONT x, x• PP = to NP