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