Transcript lfg.ppt

Lexical Functional Grammar
11-722: Grammar Formalisms
Spring Term 2004
SUBJ
PRED
TENSE
VFORM
XCOMP
S
NP
N
VP
V
PRED ‘lion’
NUM
pl
PERS
3
‘seem < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ]
VFORM INF
PRED ‘live< theme loc >’
VP-bar
SUBJ
OBL-loc
COMP VP
V
PP
P
NP
DET
N
Lions seem to live in the forest
CASE
PRED
OBJ
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
SUBJ
f1
f2
PRED
S n1
n2
NP
n3
N
VP
V
n5
TENSE
VFORM
XCOMP
n4
VP-bar
SUBJ
n6
f4
n7
COMP VP
PRED ‘lion’
NUM
pl
PERS
3
‘seem < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ] f3
VFORM INF
PRED ‘live< theme loc >’
OBL-loc
n8
f5
V
PP
n9
P
n10
NP
n11
DET
N
n12
n13
n14
Lions seem to live in the forest
CASE
PRED
OBJ
f6
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
SUBJ
f1
f2
PRED
TENSE
VFORM
XCOMP
S n1
n2
NP
n3
N
VP
V
n5
n4
VP-bar
SUBJ
n6
f4
n7
COMP VP
PRED ‘lion’
NUM
pl
PERS
3
‘seem < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ] f3
VFORM INF
PRED ‘live< theme loc >’
OBL-loc
n8
f5
V
PP
n9
P
n10
NP
n11
DET
N
n12
n13
n14
Lions seem to live in the forest
CASE
PRED
OBJ
f6
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
Properties of the mapping from cstructure 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.)
The formalism for grammatical encoding :
Local co-description of partial structures
• Φ is a mapping from c-structure nodes to fstructure 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”
()
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 cstructure 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.
Rule:
S → NP
(↑ SUBJ) = ↓
VP
↑=↓
(↑VFORM) = fin
SUBJ
Instantiated equations:
(f1 SUBJ) = f2
f1 = f3
f2
f1
PRED
f3
TENSE
VFORM
XCOMP
S f1
NP f2
N
V
VP f3
PRED ‘lion’
NUM
pl
PERS
3
‘seem < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ]
VFORM INF
PRED ‘live< theme loc >’
VP-bar
SUBJ
OBL-loc
COMP VP
V
PP
P
NP
DET
N
Lions seem to live in the forest
CASE
PRED
OBJ
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
Equivalent to drawing f-structures
on nodes as in TAG
S
[1][VFORM fin]
NP
[1] [SUBJ [2]]
VP
[1]
lion: N
(↑ PRED) = `lion’
seem: V
(↑ PRED) =
‘seem < theme > SUBJ’
XCOMP
(↑ SUBJ) =
(↑ XCOMP SUBJ)
SUBJ
-s (suffix for nouns)
(↑ NUM) = pl
- Ø (suffix for verbs)
(↑ PERS) = 3
(↑ VFORM) = fin
(↑ SUBJ NUM) = pl
PRED
S
NP
f4 N f5 V
VP
f5
TENSE
VFORM
XCOMP
PRED ‘lion’
pl
f4 NUM
PERS
3
‘seem < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ]
VFORM INF
PRED ‘live< theme loc >’
VP-bar
SUBJ
OBL-loc
COMP VP
V
PP
P
NP
DET
N
Lions seem to live in the forest
CASE
PRED
OBJ
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
lion: N
(f4 PRED) = `lion’
seem: V
(f5 PRED) =
‘seem < theme > SUBJ’
XCOMP
(f5 SUBJ) =
(f5 XCOMP SUBJ)
SUBJ
-s (suffix for nouns)
(f4 NUM) = pl
- Ø (suffix for verbs)
(f4 PERS) = 3
(f5 VFORM) = fin
(f5 SUBJ NUM) = pl
PRED
S
NP
f4 N f5 V
VP
f5
TENSE
VFORM
XCOMP
PRED ‘lion’
pl
f4 NUM
PERS
3
‘seem < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ]
VFORM INF
PRED ‘live< theme loc >’
VP-bar
SUBJ
OBL-loc
COMP VP
V
PP
P
NP
DET
N
Lions seem to live in the forest
CASE
PRED
OBJ
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
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
seem: V
VP → V VP
↑=↓ (↑ XCOMP) = ↓
(↑ PRED) = ‘seem < theme > SUBJ’
XCOMP
(↑ SUBJ) = (↑ XCOMP SUBJ)
(↑ XCOMP VFORM) = INF
SUBJ
- Ø (suffix for verbs)
(↑ VFORM) = fin
PRED
(↑ SUBJ NUM) = pl
f3
S
NP
TENSE
VFORM
XCOMP
f5
VP f3
f6
N f5 V
f7
f8 VP-bar
f8
f6COMP VP f9
f7V
PRED ‘lion’
NUM
pl
PERS
3
‘seem < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ]
VFORM INF
PRED ‘live< theme loc >’
SUBJ
OBL-loc
f9
PP
P
NP
DET
N
Lions seem to live in the forest
to: COMP
(↑ VFORM) = INF
CASE
PRED
OBJ
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
- Ø (suffix for verbs)
(↑ VFORM) = INF
live: V
(↑ PRED) = `live<theme loc>’
SUBJ OBL
seem: V
VP → V
f3=f5
(f5 PRED) = ‘seem < theme > SUBJ’
XCOMP
(f5 SUBJ) = (f5 XCOMP SUBJ)
(f5 XCOMP VFORM) = INF
SUBJ
- Ø (suffix for verbs)
(f5 VFORM) = fin
(f5 SUBJ NUM) = pl
PRED
f3
S
NP
TENSE
VFORM
XCOMP
f5
VP f3
f6
N f5 V
f7
f8 VP-bar
f8
f6COMP VP f9
f7V
VP
(f3 XCOMP) = f8
PRED ‘lion’
NUM
pl
PERS
3
‘seem < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ]
VFORM INF
PRED ‘live< theme loc >’
SUBJ
OBL-loc
f9
PP
P
NP
DET
to: COMP
(f6 VFORM) = INF
CASE
PRED
OBJ
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
- Ø (suffix for verbs)
(f7 VFORM) = INF
N
Lions seem to live in the forest
live: V
(f7 PRED) = `live<theme loc>’
SUBJ OBL
SUBJ
PRED
TENSE
VFORM
XCOMP
S
NP
N
VP
V
PRED ‘lion’
NUM
pl
PERS
3
‘try < agent theme >’
SUBJ XCOMP
pres
fin
SUBJ [ ]
VFORM INF
PRED ‘live< theme loc >’
VP-bar
SUBJ
OBL-loc
COMP VP
V
PP
P
NP
DET
Lions try
N
to live in the forest
CASE
PRED
OBJ
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
have: V
(↑ PRED) = ‘have < theme > SUBJ’
XCOMP
(↑ SUBJ) = (↑ XCOMP SUBJ)
(↑ XCOMP VFORM) = PASTPART
SUBJ
- Ø (suffix for verbs)
(↑ VFORM) = fin
PRED
(↑ SUBJ NUM) = pl
TENSE
VFORM
XCOMP
S
NP
N
VP
PRED ‘lion’
NUM
pl
PERS
3
‘have < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ]
VFORM PASTPART
PRED ‘live< theme loc >’
V
SUBJ
OBL-loc
VP
V
PP
P
NP
DET
N
Lions have lived in the forest
CASE
PRED
OBJ
OBL-loc OBJ
OBL-loc
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+
were : V
(↑ PRED) = ‘be < theme > SUBJ’
XCOMP
(↑ SUBJ) = (↑ XCOMP SUBJ)
(↑ XCOMP VFORM) = PASSIVE
SUBJ
(↑ VFORM) = fin
(↑ SUBJ NUM) = pl
PRED
TENSE
VFORM
XCOMP
S
NP
N
VP
V
PRED
OBJ
VP
V
PRED ‘lion’
NUM
pl
PERS
3
‘be < theme > SUBJ’
XCOMP
pres
fin
SUBJ [ ]
VFORM PASSIVE
PRED ‘hunt<agent theme loc >’
Ø SUBJ OBL-loc OBJ
OBL-loc
CASE OBL-loc
PP
P
NP
DET
N
Lions were hunted in the forest
‘in<OBJ>’
PRED ‘forest’
NUM sg
PERS 3
DEF
+