A Case A n a l y s i s Method C o o p e r a t i n g with ATNG
and Its A p p l i c a t i o n to Machine Translation
H i t o s h i IIDA, K e n t a r o O G U R A and Hirosato N O M U R A Musashino Electrical Communication Laboratory, N.T.T.
Musashino-shi, Tokyo, 180, Japan
Abstract
This paper present a n e w m e t h o d for parsing English sentences. T h e parser called L U T E - E J parser is combined with case analysis a n d A T N G - b a s e d analysis. L U T E - E J parser has two interesting mechanical characteristics. O n e is providing a structured buffer, Structured Constituent Buffer, so as to hold previous fillers for a case structure, instead of case registers before a verb appears in a sentence. T h e other is extended H O L D mechanism(in ATN), in whose use an e m b e d d e d clause, especially a "be- deleted" clause, is recursively analyzed by case analysis. This parser's features are (1)extracting a case filler, basically as a n o u n phrase, by A T N G - based analysis, including recursive case analysis, and (2)mixing syntactic and semantic analysis by using case frames in case analysis.
I. Introduction
In a lot of natural language processing including machine translation, A T N G - b a s e d analysis is a usual method, while case analysis is c o m m o n l y employed for J a p a n e s e l a n g u a g e processing.The parser described in this paper consists of two major parts. O n e is A T N G - b a s e d analysis for getting case elements and the other is case-analysis for getting a semantic clause analysis. L U T E - E J parser has been i m p l e m e n t e d o n a n e x p e r i m e n t a l m a c h i n e translation system L U T E (Language Understander, Translator & Editor) which can translate English into Japanese a n d vice versa. L U T E - E J is the English-to-Japanece version of L U T E .
In case analysis, two ways are generally used for parsing. O n e w a y analyzes a sentence from left to right, by using case registers. Case fillers which fill each case registers are m a j o r participants of constituents, for e x a m p l e S U B J E C T , O B J E C T , PP(Prepositional Phrase)'s and so on, in a sentence. In particular, before a verb appears, at least one participant(the subject) will be registered, for example, in the A G E N T register.
T h e o t h e r m e t h o d h a s two p h a s e s on t h e a n a l y s i s p r o c e s s i n g . I n t h e f i r s t p r o c e s s i n g , p h r a s e s a r e e x t r a c t e d as case e l e m e n t s in o r d e r to fill t h e slots of a case f r a m e . T h e second is to choose t h e a d e q u a t e case e l e m e n t a m o n g t h e e x t r a c t e d p h r a s e s for a c e r t a i n case slot a n d to c o n t i n u e t h i s process for t h e o t h e r p h r a s e s a n d t h e o t h e r c a s e slots. I n t h i s m e t h o d , t h e r e a r e no special actions, i.e. no r e g i s t e r i n g before a v e r b a p p e a r s . ( W i n o g r a d [83] )
E n g l i s h q u e s t i o n - a n s w e r i n g s y s t e m P L A N E S ( W a l t z [78] ) u s e s a s p e c i a l k i n d of c a s e f r a m e s , " c o n c e p t case f r a m e s " . By u s i n g t h e m , p h r a s e s i n a s e n t e n c e , w h i c h a r e d e s c r i b e d by u s i n g p a r t i c u l a r " s u b n e t s " and s e m a n t i c f e a t u r e s (for a p l a n e type a n d so on), a r e g a t h e r e d a n d a n action of a r e q u i r e m e n t (a s e n t e n c e ) is constructed.
2. L U T E - E J P a r s e r
2.1. L U T E - E J P a r s e r ' s D o m a i n
T h e d o m a i n t r e a t e d by L U T E - E J p a r s e r is w h a t m i g h t be c a l l e d a s e t o f " c o m p l e x s e n t e n c e s a n d c o m p o u n d s e n t e n c e s " . L e t S be a n e l e m e n t of t h i s s e t a n d l e t C L A U S E be a s i m p l e s e n t e n c e (which m i g h t i n c l u d e a n e m b e d d e d sentence). N o w , i f M A J O R - C L a n d M I N O R - C L a r e p r i n c i p a l c l a u s e a n d s u b o r d i n a t e clause, r e s p e c t i v e l y , S c a n be w r i t t e n as follows.
(R1} <S > :: = (< MINOR-CL >) < MAJOR-CL > (<MINOR-CL>)
(R2) <MAJOR-CL>::= <CLAUSE> / <S> (R3) <MINOR-CL>::= <CONJUNCTION>
<CLAUSE> (in BNF) The syntactic and semantic structure for a CLAUSE is basically expressed by a case structure. In this expression, the structure can be described by using case frames. The described structure implies t h e s e m a n t i c s t r u c t u r e i n t e n d e d by a C L A U S E a n d m a i n l y d e p e n d i n g on v e r b l e x i c a l i n f o r m a t i o n .
C a s e e l e m e n t s in a C L A U S E are N o u n P h r a s e s , object N P s of P P s or s o m e k i n d s of A D V e r b s w i t h r e l a t i o n to t i m e s a n d locations. T h e N P s t r u c t u r e is described as follows,
(R4) < N P > :: = (<NHD >){ < NP>/NOUN}( < NMP >) / < Gerund-PH > / < To-infmitive~PH > /That < CLAUSE >
w h e r e N H D ( N o u n H e a D e r ) is ~premodification" a n d N M P ( N o u n Modifier P h r a s e ) is " p o s t m o d i f i c a t i o n ' . T h u s , N M P is a s e t i n c l u d i n g v a r i o u s k i n d s o f e m b e d d e d f i n i t e c l a u s e s , r e l a t i v e or b e - d e l e t e d r e l a t i v e f i n i t e clauses.
2.2. L U T E - E J P a r s e r Overview
A f t e r m o r p h o l o g i c a l a n a l y s i s w i t h l o o k i n g u p
words for a n i n p u t s e n t e n c e in t h e d i c t i o n a r y , a n i n p u t sentence a n a l y s i s is b e g u n from left to r i g h t . Thus, a f t e r a verb h a s been seen, i t m a k e s progress to a n a l y z e a C L A U S E by r e f e r r i n g to t h e case f r a m e c o r r e s p o n d i n g to the verb, a s each slot in t h e case f r a m e is filled w i t h a n N P or an object of PP. A case slot consists of t h r e e elements: one s e m a n t i c f i l l e r condition slot a n d two s y n t a c t i c a n d s e m a n t i c m a r k e r
s l o t s . H e r e , a p r e p o s i t i o n is d i r e c t l y u s e d a s a
s y n t a c t i c m a r k e r . F u r t h e r m o r e , f o u r p s e u d o
m a r k e r s , ~subject", "object", ~ i n d i r e c t - o b j e c t " a n d ~complement", a r e used. A s a s e m a n t i c m a r k e r , a so- called deep case is used (now, 41 r e a d y for t h i s case
s y s t e m ) . T h e n , L U T E - E J P a r s e r e x t r a c t s t h e
s e m a n t i c s t r u c t u r e i m p l i e d in a s e n t e n c e (S o r C L A U S E ) a s an e v e n t or s t a t e i n s t a n c e c r e a t e d from a case frame, which is a class or a prototype. A n N P is p a r s e d by the A T N G - b a s e d a n a l y s i s in order to decide a case slot filler {now, 81 nodes on t h i s ATNG).
N e x t , t h e r e a s o n w h y t h e c a s e a n a l y s i s a n d A T N G - b a s e d a n a l y s i s are m e r g e d will be s t a t e d . I t h a s two m a i n points.
O n e p o i n t i s a b o u t t h e d e p t h o f e m b e d d e d s t r u c t u r e s . F o r e x a m p l e , t h e i n v e s t i g a t i o n on t h e d e g r e e of a C L A U S E c o m p l e x i t y r e s u l t e d in t h e necessity to h a n d l e a h i g h degree of c o m p l e x i t y w i t h efficiency. The N M P s t r u c t u r e is also m o r e complex. I n p a r t i c u l a r , e m b e d d e d V P s or A D J P H s a p p e a r
r e c u r s i v e l y . T h e r e f o r e , a r e c u r s i v e p r o c e s s f o r
a n a l y z i n g N P is needed.
T h e o t h e r p o i n t is a b o u t t h e r e p r e s e n t a t i o n of
g r a m m a t i c a l s t r u c t u r e s . G r a m m a r d e s c r i p t i o n s
s h o u l d be e a s y to r e a d a n d write. R e p r e s e n t a t i o n s by u s i n g case f r a m e s m a k e r u l e s of a n y k i n d for N M P v e r y simple, d e s c r i b i n g no N M P contents.
I n o r d e r to d e a l w i t h t h e a b o v e t w o p o i n t s , c o m b i n i n g t h e c a s e a n a l y s i s w i t h A T N G - b a s e d
a n a l y s i s s o l v e s t h o s e p r o b l e m s . V e r b a l
N M P ( V T Y P E - N M P ) s a r e d e a l t w i t h b y r e e u r s i v e case-analyzing
2.3. Structured Constituent Buffer
A s mentioned above, syntactic and semantic
structures are basically derived from a sentence by
analyzing a C L A U S E . Analysis control depends on
t h e c a s e f r a m e , w h e n t h e v e r b h a s b e e n j u s t a p p e a r i n g in a C L A U S E . H o w e v e r u n t i l s e e i n g the verb, all of t h e p h r a s e s , w h i c h m a y be n o u n p h r a s e s w i t h e m b e d d e d clauses, P P s or A D V s before the verb, m u s t be h e l d in c e r t a i n r e g i s t e r s or buffers.
H e r e , a n e w b u f f e r , S T R u c t u r e d C O N s t i t u e n t B u f f e r ( S T R C O N B ) , i s i n t r o d u c e d to h o l d t h e s e
p h r a s e s . T h i s b u f f e r h a s s u r f a c e c o n s t i t u e n t s
s t r u c t u r e , a n d consists of specific slots. T h e r e a r e two
s l o t t y p e s . One is a r e g i s t e r to c o n t r o l E n g l i s h
a n a l y s i s a n d t h e o t h e r i s a b u f f e r to h o l d s o m e m e n t i o n e d - a b o v e constituents. The first type h a s two slots ; one is s i m i l a r to a b l a c k b o a r d a n d r e g i s t e r s t h e n a m e s of unfilled-slots. The o t h e r s t a c k s t h e n a m e s of filled-slots in o r d e r of p h r a s e a p p e a r a n c e a n d is used for b a c k t r a c k i n g in t h e a n a l y s i s . The second slot t y p e i n v o l v e s s e v e r a l k i n d s of procedures. One of the m a i n p r o c e d u r e s , ~ g e t p h r a s e " , e x t r a c t s s o m e c a n d i d a t e s for t h e slot f i l l e r from t h e l e f t side of a C L A U S E . I t fills t h e slot w i t h t h e s e c a n d i d a t e s . T h i s procedure t a k e s one a r g u m e n t , which is a c o n s t i t u e n t m a r k e r , ~ p r e p o s i t i o n a l - p h r a s e " , ~ n o u n - p h r a s e " a n d so on (in practice, u s i n g each a b b r e v i a t i o n ) .
F o r e x a m p l e , w h e n t h e f o l l o w i n g s e n t e n c e is given, the e v a l u a t i o n for ~(getphrase 'preph)"in L I S P
r e t u r n s o n e s y m b o l g e n e r a t e d f o r t h e h e a d
p r e p o s i t i o n a l p h r a s e , ~ n the m a c h i n e l a n g u a g e " , and d e t e r m i n e s t h e slot filler.
(sl) '~In t h e m a c h i n e l a n g u a g e e a c h b a s i c
m a c h i n e o p e r a t i o n is r e p r e s e n t e d b y t h e n u m e r i c a l code t h a t i n v o k e s i t in t h e computer, a n d ... "
However, if t h e a r g u m e n t is ~verb", t h i s procedure only tells t h a t the top word of unprocessed C L A U S E is a verb. A t t h a t m o m e n t , the process of f i l l i n g with
slots in S T R C O N B ends. T h e n case analysis starts.
2.4. C L A U S E Analysis
After seeing a verb in a C L A U S E , that is, filling
the verb slot in the S T R C O N B , the case analysis
starts. W h e n the parser control moves on the case
frame, the analyzer falls to work in order to fill the
first case slot, w h i c h is generally one for the
constituent S U B J E C T and for the case A G E N T or
I N S T R U M E N T , etc. in the semantic structure. This
first slot is special, because the filler has already been
predicted in the slot for S U B J E C T in S T R C O N B . Therfore, the predicted phrase is tested to determine
whether or not it satisfies the semantic condition of
the first case slot. If it is good, the slot is filled with it
as a case instance. The parser control moves to the
next case slot and a candidate phrase for it is
extracted from the remainder of the input sentence by
a r g u m e n t . T h i s s l o t is u s u a l l y O B J E C T , or obligatory prepositional phrase n a m e if the verb is intransitive. Furthermore, the control moves to the n e x t case slot to fill i t , i f the case f r a m e h a s more slots, all of which are obligatory case slots. They are described in a m e a n i n g s l o t (whose v a l u e is a m e a n i n g frame) in a case frame, while optional case slots are united in a special frame.
The process to fill the case slots is continuing until the end of the case frame. Then, more t h a n one candidate for a case s t r u c t u r e m a y be e x t r a c t e d . More than one for an N P extracted by " g e t p h r a s e " gives m a n y case structures, because of the difference in i n p u t remainders.
Next, recusive p a r s i n g will be m e n t i o n e d . In a n a l y z i n g e m b e d d e d c l a u s e s , w h i c h are V T Y P E - NMPs. C L A U S E a n a l y s i s also gets in use of N P s parsing. It is supported with a new STRCONB. The procedure to call NP analysis is described in the n e x t section. The c o n c e p t u a l d i a g r a m for L U T E - E J analysis as a recusive CLAUSE is shown in Fig.1.
STRUCTURED-CONSTITUENT-BUFFER
l <*sub ... >
l
L--. Case Analysis ! ] *case-frame*
<*agent> <*object> <*recipient >
STRUCTURED-CONSTITUENT-BUFFER •
L.._ Case Analysis [
*case-frame*
<*agent>
J
I
<*object>
I
__~ STRUCTU~D-CONSTITUZNT-BUFFER I
~
C a s e Analysis [ ]Fig.1 Conceptual D i a g r a m of L U T E - E J Analysis
analysis of
i NOUN
PhraseATNG-based analysis
process
(embedded clause,
noun clause
I.
I
2.5. NP Analysis
An N'P structure is basically described as the rule (R4). In this paper, NHD structure and the analysis for it a r e o m i t t e d . N M P is a n o t h e r m a i n N P constituent and will be explained here.
NM:P is described in the following form. (R5) < NMP > : : =
< P P > i <PResent-Participle-PHrase> / <PaSt-Participle-PH > / <ADJective-PH> / <INFinitive-PH > / <RELative-PH > / <CARDINAL> <UNIT> <ADJ>
If an NMP is represented by any kind of VP or ADJ-PH, it is described in a case structure by using a case frame. That is, VTYPE-NMPs are parsed in the same way as CLAUSEs. However, a VTYPE-NMP has one (or more) structural missing element (a hole) c o m p a r e d w i t h a C L A U S E . T h e r e f o r e , complementing them is needed by restoring a reduced form to the complete C L A U S E . Extending " H O L D ' - manipulation in A T N m a k e s it possible. This extension deals with not only relative clauses but also V T Y P E - N M P s . That is, the phrases with a "whiz- deletion" in Transformational G r a m m a r can be treated. A D J - P H s can also be treated. For example, the following phrase is discussed.
(s2) '~I k n o w an actor suitable for the part."
In the above case, the deletion of the words, "who is", results in the complete s e n t e n c e b e i n g t h e a b o v e representation. The e x t e n d i n g HOLD-mm~ipulation holds the antecedent of a C L A U S E with a V T Y P E - N M P . Calling the case analysis recursively, the V T Y P E - N M P is parsed by it. Each V T Y P E - N M P has a specific type, P R P - P H , P S P - P H , I N F - P H or A D J - PH. Each of them looks for an antecedent, as the object or the subject: so that each is treated according to the procedure to decide the role of the antecedent and the omitting grammatical relation. Therefore, it is necessary to introduce one "context" representing V T Y P E - N M P . The present extension d e m a n d s the context with the antecedent a n d calls the case analysis.
T h e following structured representation describes a N O U N , as stated above.
(NOUN
(*TYPE ($value (instance)))
(*CATEGORY ($value Csemantic-category'))} (*SELF ($value ("entry-name')))
(*POS ($value (noun)))
(*MEANING ($value ("each-meaning-frame-list"))) (*NUMBER ($value ("singular-or-plural")))
(*MODIFIERS ($value CNHD-or-NMP-instance-list"))) (*MODIFYING ($value Cmodificand")))
(*APPOSITION($value (" appositional-phrase-instance"))) (*PRE ($value Cprepositional-phrase-instance"))) (*COORD ($value ("coordinate-phrase"))))
Each word with prefix "*" describes a slot n a m e such as a case f r a m e has. H o w e v e r m a n y s l o t s a r e prepared for holding pointers to represent a syntactic structure of an NP. The v a l u e for V T Y P E - N M P s * M O D I F I E R S is a p a i r of V T Y P E - N M P s and an i n d i v i d u a l v e r b a l symbol, for e x a m p l e , " ( P R P - P H verb*l)".
Complementing NP's structure, an appositional
structure is introduced. It is described in
*APPOSITION-slot and treated in the same w a y as
N M P s . Those phrases are discriminated from
another N M P by a pair of a delimiter ~," and a phrase
terminal symbol, or, in particular, by proper nouns.
A Coordinate conjunction is another important
structure for an NP. There are three kinds of
coordinates in the present N P rule. The first is
between NPs, the second is N H D s , and the third is NMPs. The NP r e p r e s e n t a t i o n with t h a t conjunction is described by an i n d i v i d u a l c o o r d i n a t e s t r u c t u r e . T h a t is, the conjunction looks like a predicate w i t h a n y N P s a s p a r a m e t e r s , for e x a m p l e , ( a n d N P 1 NP2 ... NPi). Therfore, the coordinate s t r u c t u r e h a s " * C O O R D I N A T E - O B J E C T S " and "*OBJ-CAT'" slot, e a c h of w h i c h is f i l l e d w i t h a n y i n s t a n c i a t e d N P / N H D / N M P s y m b o l or a n y c o o r d i n a t e t y p e , r e s p e c t i v e l y .
Some l i n g u i s t i c h e u r i s t i c s a r e n e e d e d to p a r s e NPs, along w i t h e x t r a c t i n g a s few i n a d e q u a t e N P
s t r u c t u r e s a s p o s s i b l e . S e v e r a l h e u r i s t i c s a r e
i n t r o d u c e d into L U T E - E J parser. T h e y are shown as follows.
(1) H e u r i s t i c s for a compound N P
" G e t p h r a s e " function v a l u e for an N P is the l i s t of
c a n d i d a t e s for a n a d e q u a t e N P s t r u c t u r e . T h e
function first e x t r a c t s the l o n g e s t N P c a n d i d a t e from a n input. In t h i s a n a l y s i s , i t s end word is s e p a r a t e d from t h e r e m a i n d e r of t h e i n p u t b y some heuristics, (a) The top w o r d in t h e r e m a i n d e r i s a p e r s o n a l pronoun.
(b) Its end word h a s a p l u r a l form. (c) Its top is a d e t e r m i n e r .
T h e s e h e u r i s t i c s p r e v e n t t h e v a l u e from h a v i n g a b u n d a n t n o n - s e m a n t i c a l structures.
(2) I-Ieuristics b y u s i n g contexts
W h e n N P a n a l y s i s is called when f i l l i n g a case slot, the c a s e - m a r k e r ' s v a l u e for i t is d e l i v e r e d to N'P
a n a l y s i s . T h i s v a l u e is c a l l e d " s y n t a c t i c l o c a l
context". I t is useful in rejecting pronouns, which are u n g r s m m a t i c a l l y inflected, b y t e s t i n g the a g r e e m e n t w i t h the s y n t a c t i c local context and t h e subject or the
object. A n o t h e r c o n t e x t u s a g e is s h o w n b e l o w .
A s s u m e t h a t a p h r a s e c o n t a i n i n g a c o o r d i n a t e conjunction '~and", for example, is in a context which is an object or a complement, and the word n e x t to the
c o n j u n c t i o n is a p r o n o u n . I f t h e p r o n o u n is a
subjective case, the conjunction is d e t e r m i n e d to be one b e t w e e n CLAUSEs. To t h e c o n t r a r y , the pronoun b e i n g a objective case d e t e r m i n e s the conjunction to connect a n N P w i t h it.
(3) Apposition
M a n y v a r i o u s k i n d s of a p p o s i t i o n s a r e u s e d in texts. Most of t h e m are shown by N. S a g e r [80]. The preceding a p p o s i t i o n a l s t r u c t u r e s a r e used.
3. L U T E - E J P a r s e r M e r i t s
3.1. A M e r i t of U s i n g Case A n a l y s i s
In two sentences, each h a v i n g different s y n t a c t i c structures, t h e r e is a problem involved in i d e n t i f y i n g each case by e x t r a c t i n g s e m a n t i c r e l a t i o n s between a p r e d i c a t e a n d a r g u m e n t s ( N P s , or N P s h a v i n g p r e p o s i t i o n a l m a r k s ) . L U T E - E J case a n a l y s i s h a s solved t h i s problem by i n t r o d u c i n g a new case slot w i t h t h r e e components (Section 2.2.). F o r case frames in L U T E - E J a n a l y s i s c o n t a i n i n g t h e s l o t s , a n a n a l y s i s r e s u l t has two f e a t u r e s a t the s a m e t i m e . One is a surface s y n t a c t i c s t r u c t u r e and the o t h e r is a s e m a n t i c s t r u c t u r e in two slots. Therefore, m a n y case f r a m e s are p r e p a r e d according to p r e d i c a t e m e a n i n g s and case f r a m e s a r e p r e p a r e d according to p r e d i c a t e
meanings and syntactic sentence patterns, depending
on one predicate (verb).
A n analysis example is s h o w n for the s a m e
semantic structure, according to which there are three different syntactic structures. These three
sentences are as follow (from Marcus [80] ).
(s3) "The judge presented the prize to the boy."
(s4) ~The judge presented the boy with the prize." (s5) "The judge presented the boy the prize."
Three individual structures are obtained for each sentence and their meaning equivalence for each slot
is proved by matching the fillers of case-instances and
by doing the same for case-names.
Incidentally, a sentence containing another
meaning of "present" is as follows. It m e a n s "to show
or to offer to the sight", for example, in a sentence,
(s6) ~l~ney presented the tickets at the gate."
In this case, the "present" frame m u s t prepare the
obligatory "at" case slot.
3.2. A n Effect of Combining Case Analysis with
A T N G - b a s e d Analysis
The next section shows one application of the L U T E - E J parser, which is a machine translation
system. So, taking the translated sample sentence in
Section 4., effective points in parsing are s h o w n in
this section. The sample sentence is as follows.
(s7) ~In the higher-level p r o g r s m m i n g languages
the instructions are complex statements, each equivalent to several m a c h i n e - l a n g u a g e instructions, a n d they refer to m e m o r y
locations by n a m e s called variables."
O n e point is N M P analysis method by recursive
NMP phrases are seen.
(a) The phrase which is an adjective p h r a s e and
modifies "each", appositive
to the preceding "statements",
(b) The phrase which is a p a s t participle phrase
and modifies "names".
These phrases are analyzed in the same case frame a n a l y s i s , e x c e p t for t h e p h r a s e d e l e t i o n t y p e s (depending on VTYPE-NMP) a p p e a r i n g in them. The deleted phrases are the subject p a r t and the object p a r t respectively. J u d g i n g from the point of a p a r s i n g
m e c h a n i s m , e x t e n d e d H O L D - m a n i p u l a t i o n
t r a n s p o r t s the deleted phrases, "each" and "names", with the contexts to the case frame analysis.
The other point is to hold undecided case elements in STRCONB. The head PP and the subject in the sentences, for example, are buffering until seeing the m a i n verb.
4. An Application to Machine T r a n s l a t i o n
One of the effective applications can be shown by c o n s i d e r i n g t h e N M P a n a l y s i s w i t h e m b e d d e d phrases. These NMPs are represented by instances of actions, i.e. i n d i v i d u a l case f r a m e s which m a y be h a v i n g an unfilled case slot. A p p l y i n g L U T E - E J p a r s e r to an a u t o m a t i c machine t r a n s l a t i o n system,
there m a y be a little problem in l a c k i n g the case slots i n f o r m a t i o n . The r e a s o n is b e c a u s e t h e l a c k i n g information can be t h o u g h t of as b e i n g i n d i s p e n s a b l e for a semantic structure in one l a n g u a g e , for example a t a r g e t l a n g u a g e J a p a n e s e , in spite of h a v i n g them in a n o t h e r languages, for example a source l a n g u a g e English. The p r o b l e m is t h e difference in how to modify a h e a d noun by an N M P or an e m b e d d e d clause.
In J a p a n e s e , a N O U N is often m o d i f i e d by an embedded clause in the following pattern.
"<predicate's arguments>* <predicate> NOUN" ; * representing recursive applications Therefore, in J a p a n e s e , an N M P p h r a s e represented by a case frame corresponds to an embedded clause a n d t h e v e r b of t h e f r a m e c o r r e s p o n d s to t h e predicate.
A t r a n s l a t i o n example is shown in Fig.2.
References
M a r c u s , M i t c h e l l P., "A T h e o r y o f S y n t a c t i c Recognition for N a t u r a l Language", MIT Press, 1980. S a g e r , N a o m i , " N a t u r a l L a n g u a g e I n f o r m a t i o n Processing", Addison-Wesley, 1981.
Waltz, David L., "An E n g l i s h L a n g u a g e Q u e s t i o n - A n s w e r i n g System for a L a n g u a g e R e l a t i o n a l D a t a Base", CACM Vol.21, 1978.
Winograd, Terry, " L a n g u a g e as a Cognitive Process", Vol.1, Addison-Wesley, 1983.
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G e n e r a t e d Internal Representation Processes Window Fig. 2 A n E x a m p l e of LUTE T r a n s l a t i o n Results on the Display
(from EngLish to J a p a n e s e )
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