Lexical Functional Grammar

Lexical Functional Grammar

11-722: Grammar Formalisms

Spring Term 2004

Lions seem to live in the forest

DET N

P NP

V PP

COMP VP

N V VP-bar

NP VP

S

SUBJ PRED ‘lion’ NUM pl PERS 3PRED ‘seem < theme > SUBJ’ XCOMPTENSE presVFORM finXCOMP SUBJ [ ] VFORM INF PRED ‘live< theme loc >’ SUBJ OBL-loc OBJ

OBL-loc CASE OBL-loc PRED ‘in<OBJ>’ OBJ PRED ‘forest’ NUM sg PERS 3 DEF +


DET N

P NP

V PP

COMP VP

N V VP-bar

NP VP

S



f1

f3

f2

f4

f5 f6

n7

n6n5

n4

n3

n2

n1

n10n9

n8

n11n13

n12

n14

Properties of the mapping from c-structure to f-structure

• Each c-structure node maps onto at most one f-structure node.

• More than one c-structure node can map onto the same f-structure node.

• An f-structure node does not have to correspond to any c-structure node. (But the information it contains does come from somewhere – either a grammar rule or lexical entry.)

• Φ is a mapping from c-structure nodes to f-structure nodes. – There are other mappings to semantic structures,

argument structures, discourse structures,etc.

• * is the “current” c-structure node (me).• Φ(*) is “my f-structure” ()• m(*) is “my c-structure mother”• Φ(m(*)) is “my c-structure mother’s f-structure”

()

The formalism for grammatical encoding :Local co-description of partial structures

Local co-description of partial structures

• S NP VP ( SUBJ) = = NP says: My mother’s f-structure has a SUBJ

feature whose value is my f-structure.VP says: My mother’s f-structure is my f-structure.This rule simultaneously describes a piece of c-

structure and a piece of f-structure.It is local because each equation refers only to the

current node and its mother. (page 119-120)

Other types of equations

• F-structure composition– ( SUBJ NUM) = sg– My f-structure has a subj feature, whose value is

another f-structure, which has a num feature, whose value is sg.

– Usually, path names are not longer than two.

• Two features pointing to the same value:– ( SUBJ) = ( XCOMP SUBJ)– ( SUBJ) = ( TOPIC)

• ( ( CASE)) = (Dalrymple pages 152-153)– Sam walked in the park.– ( CASE) = OBL-loc– ( OBL-loc) =

The minimal solution

• The f-structure for a sentence is the minimal f-structure that satisfies all of the equations. (page 101).

Building an F-structure: informal, for linguists

• Annotate– Assign a variable name to the f-structure corresponding to

each c-structure node. – May find out later that some of them are the same.

• Instantiate – Replace the arrows with the variable names.

• Solve– Locate the f-structure named on the left side of the equation.– Locate the f-structure named on the right side of the equation– Unify them.– Replace both of them with the result of unification.


DET N

P NP

V PP

COMP VP

N V VP-bar

NP f2 VP f3

S f1



Rule:S → NP VP (↑ SUBJ) = ↓ ↑=↓ (↑VFORM) = fin

Instantiated equations: (f1 SUBJ) = f2f1 = f3

f1f2

f3

Equivalent to drawing f-structures on nodes as in TAG

S

[1][VFORM fin]

NP VP

[1] [SUBJ [2]] [1]


DET N

P NP

V PP

COMP VP

f4 N f5 V VP-bar

NP VP

S



lion: N seem: V(↑ PRED) = `lion’ (↑ PRED) =

‘seem < theme > SUBJ’ XCOMP (↑ SUBJ) = (↑ XCOMP SUBJ) -s (suffix for nouns) (↑ NUM) = pl - Ø (suffix for verbs)(↑ PERS) = 3 (↑ VFORM) = fin (↑ SUBJ NUM) = pl

f5

f4


DET N

P NP

V PP

COMP VP

f4 N f5 V VP-bar

NP VP

S



lion: N seem: V(f4 PRED) = `lion’ (f5 PRED) =

‘seem < theme > SUBJ’ XCOMP (f5 SUBJ) = (f5 XCOMP SUBJ) -s (suffix for nouns) (f4 NUM) = pl - Ø (suffix for verbs)(f4 PERS) = 3 (f5 VFORM) = fin (f5 SUBJ NUM) = pl

f5

f4

What is an XCOMP• A non-finite clause, predicate nominal, predicate

adjective, or predicate PP– Sam seemed to be happy (VP)– Sam seemed happy (AP)– Sam became a teacher (NP)– We had them arrested (VP)– We kept them in the drawer (PP)

• Has to be an argument of a verb:– Arrested by the police, Sam had no alternative but to

give up his life of crime. • This is an adjunct, not an XCOMP

• Gets its subject by sharing with another verb:– I think that Sam is happy.

• This is a COMP, not an XCOMP


DET N

P NP

f7V PP

f6COMP VP f9

N f5 V f8 VP-bar

NP VP f3

S



seem: V

(↑ PRED) = ‘seem < theme > SUBJ’ XCOMP

(↑ SUBJ) = (↑ XCOMP SUBJ)

(↑ XCOMP VFORM) = INF

- Ø (suffix for verbs)

(↑ VFORM) = fin

(↑ SUBJ NUM) = pl

to: COMP - Ø (suffix for verbs)

(↑ VFORM) = INF (↑ VFORM) = INF

live: V

(↑ PRED) = `live<theme loc>’ SUBJ OBL

VP → V VP ↑=↓ (↑ XCOMP) = ↓

f3

f5

f9

f8

f7

f6


DET N

P NP

f7V PP

f6COMP VP f9

N f5 V f8 VP-bar

NP VP f3

S



seem: V

(f5 PRED) = ‘seem < theme > SUBJ’ XCOMP(f5 SUBJ) = (f5 XCOMP SUBJ) (f5 XCOMP VFORM) = INF

- Ø (suffix for verbs)(f5 VFORM) = fin (f5 SUBJ NUM) = pl

to: COMP - Ø (suffix for verbs)(f6 VFORM) = INF (f7 VFORM) = INF

live: V(f7 PRED) = `live<theme loc>’ SUBJ OBL

VP → V VP f3=f5 (f3 XCOMP) = f8

f3

f5

f9

f8

f7

f6

Lions try to live in the forest

DET N

P NP

V PP

COMP VP

N V VP-bar

NP VP

S

SUBJ PRED ‘lion’ NUM pl PERS 3PRED ‘try < agent theme >’ SUBJ XCOMPTENSE presVFORM finXCOMP SUBJ [ ] VFORM INF PRED ‘live< theme loc >’ SUBJ OBL-loc OBJ


Lions have lived in the forest

DET N

P NP

V PP

VP

N V

NP VP

S

SUBJ PRED ‘lion’ NUM pl PERS 3PRED ‘have < theme > SUBJ’ XCOMPTENSE presVFORM finXCOMP SUBJ [ ] VFORM PASTPART PRED ‘live< theme loc >’ SUBJ OBL-loc OBJ


have: V

(↑ PRED) = ‘have < theme > SUBJ’ XCOMP


(↑ XCOMP VFORM) = PASTPART

- Ø (suffix for verbs)

(↑ VFORM) = fin

(↑ SUBJ NUM) = pl

Lions were hunted in the forest

DET N

P NP

V PP

VP

N V

NP VP

S

SUBJ PRED ‘lion’ NUM pl PERS 3PRED ‘be < theme > SUBJ’ XCOMPTENSE presVFORM finXCOMP SUBJ [ ] VFORM PASSIVE PRED ‘hunt<agent theme loc >’ Ø SUBJ OBL-loc OBJ


were : V

(↑ PRED) = ‘be < theme > SUBJ’ XCOMP


(↑ XCOMP VFORM) = PASSIVE

(↑ VFORM) = fin

(↑ SUBJ NUM) = pl

Lexical Functional Grammar

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