Language Syntax
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FORMAL SPECIFICATION OF NATURAL LANGUAGE SYNTAX ABSTRACT The two-level grammar is investigated as a notation for giving formal specification of the context-frec and context-sensitive aspects of n,~tural language syntax . In this paper, a large class of English declarative sentences, including post-noun-modificatlon by relative clauses, is formalized using a two-level grammar. The principal advantages of two- level grammar are: 1) it is very e~sy to understand and may be used to give a formal description using a structured form of natural language; 2) it is formal with many well-known mathematical properties; and 3) it is directly imp lemen table by in terpreta tion. Th e significance of the latter fact is that once we have written a two-level grammar for natural language syntax, we can derive a parser autom atically without writing any additional specialized computer programs. Because of the ease with which two-levcl grammars may express logic and their Turing computability we expect that they will also bc very snitable for future extensions to semantics and know ledge representation. 1. INTROD UCTION Formal specifications of natural language syntax should serve as a standard definition for the syntax of the subject language. The specification must be complete, concise, consistent, precise, unambiguous, understandable, and useful to language scholars, users, and implcmentors who wish to develop a parser for the tanguagc to run on a computer. Furthermore the specification should be mathematically rigorous to the degree that an implementation of the language can be automatically derived from the specification {10]. Unfortunately many of these aims arc difficult to accomplish primarily because of the dynan ric and informal nature of natu ral lan guage. Form al specification is still a wo rthy go al to the degree allowed by present knowledge about natm'al language and iu this paper we propose a mctalanguage for specifying both syntax and semantics of natural language that has potential for satisfying these goals. The mctalanguage we propose is the two-levd grammar [16} (also called W-grammars and tlgs). Two-level grammars have been used extensively for specifying the syntax and semantics of programming languages [2] but their use in specifying natural language was first introduced by the authors [7 , 8, 9]. Existing formal specification mcthods for natural language syntax take many forms. Of these, some of the more common are augmented transition network grammars [181, transformational grammars [1], and generalized phrase-structure grammars [5]. These methods and others arc also surveyed in [17]. The degree to which any formal specification method satisfies the above stated goals is sometimes difficult to evaluate and relies on subjectivity. The au thors do not intend to evaluate these existing methods with respect to the requirements of formal specification languages but will instead concentrate on w hy two-level gramm ars satisfy the necessary goals in a mathematically rigorous but readable and easy to understand way. In this paper, the two-level grammar mctalanguage will be used to define a large classification of English declarative sentences, extending work described in [8] and [9]. We will emphasize the method of using two-level grammars for this purpose and the advantages gained rather than any particular characteristics of the given grammar. 2 . TWO-LEVEL GRAMMARS A two-level gra mm ar consists of two sel)aratc gramm ars, the mstaprodu ctlon rule~ (metarules) and the hyperrules. The metarules are generally context-free rules which ta ke the form : METANOTION :: hypcrnotion-1; hypcrnotlon-2; ... ; hypernotion-n. where ME TA NO TI ON is tile left-hand side "nonterminal" symbol of the production and hypernotion-1, hypernotlon-2, ... hypcrnotion-n are the n alternatives of the production right-hand side. Each hypcrnotion consists o f protonotions (terminal symbols) and other metanotions. In the case of English, the terminal symbols of the recta-grammar are English words. The recta-grammar itself is used to definc the context-free ~spccts of English. Example metarules arc: SENTENCE :: DETERMINER NOUN VERB. DETERMINER :: a; an; tile; these; those; this; that. USING TWO-LEVEL GRAMMAR Barrett R . Bryant Dale Johnson Balanj aninat~h Edupuganty Department of Computer and Information Sciences The University of Alabama at Birmingbam Birmingham, Alabama, U. S.A. 35294 The hypcrrules are of the form hypcrnot]on ; hyperaltern-1; hyper~ltern-2; ... ; hyperaltern-n. Tile hyperalternatives separated by semicolons arc distinct production alternatives. Each of these hyperaltcrn atives may be divided into a sequence of hypernotions separated by commas. In a two-level grammar derivation tree, there will be one br:mch for each clement in the sequeucc. A t w o - le v e l gramm ar with either hyperrnles having more than one hyperaltcrnative or two distinct hypcrrules having the same hypcrnotion on the production left-hand side is nondetcrministic. [f cach hYl)crrule has only one hyperalternative and all hypcrnotions in production left-hand sides are distinct from mm another then the tlg is dcterminisl;ic. A hyp crrule is actually a production rule "pa ttern" since each hyperrule can possibly represent an infinite number of production rules in a context-free gra mm ar. T his is because each occurrence of a metan otion in the hypcrrulc represents all sequences of protonotions that can be derivcd from that metanotion. T hat is, a hyperrule may be viewed as a set of production rules (called strict production rules) in which all metanotions are replaced by the protonotions they derive. The only restriction here is that if there arc more than one occurrcnce of a single rnetanotion, then each is replaced by the same protonotion sequence in deriving the strict production rules. This is called conM stent substitution. For example, in the byperrulc where WO RD is WO R]) : true. both occurrences of the metano tion WORD repr~en t the same protono tion. The set of allowable protonotions in this rule is defined by the metarulcs for WORD. If these metarules define an infinite number of possible protonotions, then tile above hyperrule also represents an infinite uumbcr of strict i)roduction rules. [t is tiffs featurc of two-level grammars that allow tbcm to define context-sensitive and recursivcly enum crable languages [12]. If consistent substitution is not required (or desired) for metanotions with the same root metarulcs (and nanm), then these metanotions may be distinguished by subscripts. For example, where SENTENCE1 and SENTENCE2 are correct ; where SENTENCE1 is corre, ct, where SENTE NCE 2 is correct. In this hypcrrule, SENT:ENOE1 and SENTENCE~. are defined by the same metarulcs (and root mctanotion SENTENCE} but need not have the same instantiations. Some hypcrrules called predicates act as conditions which must be satisfied for the derivation to be :~uccessful. A predicate begins with the word where or coadition and the terminal derivation of the hyperrule is the empty string if the condition is satisfied and will derive a "blind alley" (i.e. not derive any terminal string) if the condition is not satisfied. In tire two-level grammar of English presented in this paper, all hyperrules arc predicates and serve to perform c ontext checks such as subject-ver b agreement, object~vcrb agreement, and any additional required context cheeks which cannot be conveniently specified by a eontext-frce grammar (i.e. tile mctarules). 3. METARULES FOR ENGLISH Tile metarulcs of the two-level gram ma r for English define ti r e context-free a~pccts of English synt*Lx. Some lexical items from English can not be easily defined in a forinal way (i.e. using context-free rules). These include tile nouns, verbs, adjectives, proper names, and titles, given names and sur nam es for people which arc lcxical categories containing a large number of elements. The formal specification of these categories would be production rules of tlm form: NOUN :: aardvarkl abacus; ...; zucchlnL VERB :: abandon; abate; ...; zoom. ADJE CTIV E :: abdominal; abho rrenti ..4 znhcd. PROPER_NAME :: Aberdeen; Abilenc; ...; Zambia. TITLE :: Admiral; Archblslmp; ...; Warrant Officer. For simplicity we choose to omit more formal specifications of the above categories. A more complete list of words in these categories may bc found in [14]. 5 2 7
Transcript of Language Syntax
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F O R M A L S P E C I F I C A T I O N O F N A T U R A L L A N G U A G E S Y N T A X
A B S T R A C T
T h e t w o - le v e l g r a m m a r i s in v e s t i g a t e d a s a n o t a t i o n f o r g i v i n g fo r m a l
s p e c i f i c a ti o n o f t h e c o n t e x t - f r e c a n d c o n t e x t - s e n s i t i v e a s p e c t s o f n , ~ t u r a l
l a n g u a g e s y n t a x . I n t h i s p a p e r , a l a r g e cl a s s o f E n g l i s h d e c l a r a t i v e
s e n t e n c e s , i n c l u d i n g p o s t - n o u n - m o d i f i c a t l o n b y r e l a t i v e c l a u s e s , i s
f o r m a li z e d u s i n g a t w o - le v e l g r a m m a r . T h e p r i n c i p a l a d v a n t a g e s o f t w o -
l ev el g r a m m a r a r e : 1 ) i t i s v e r y e ~ s y t o u n d e r s t a n d a n d m a y b e u s e d t o
g i v e a f o r m a l d e s c r i p t i o n u s i n g a s t r u c t u r e d f o r m o f n a t u r a l l a n g u a g e ; 2 ) i t
i s f o r m a l w i t h m a n y w e l l - k n o w n m a t h e m a t i c a l p r o p e r t ie s ; a n d 3 ) i t i s
d i r e c t l y i m p l e m e n t a b l e b y i n t e r p r e t a t i o n . T h e s i g n i f i c a n c e o f t h e l a t t e r f a c t
i s t h a t o n c e w e h a v e w r i t t e n a t w o - l ev e l g r a m m a r f o r n a t u r a l l a n g u a g e
s y n t a x , w e c a n d e r iv e a p a r s e r a u t o m a t i c a l l y w i t h o u t w r i t i n g a n y
a d d i t i o n a l s p e c i a l iz e d c o m p u t e r p r o g r a m s . B e c a u s e o f t h e ea s e w i t h w h i c h
t w o - le v c l g r a m m a r s m a y e x p re s s lo g i c a n d t h e i r T u r i n g c o m p u t a b i l i t y w e
e x p e c t t h a t t h e y w i l l a l s o b c v e r y s n i t a b l e f o r f u t u r e e x t e n s i o n s t o
s e m a n t i c s a n d k n o w l e d g e r e p r e s e n t a t i o n .
1 . I N T R O D U C T I O N
F o r m a l s p e c if i c at i o n s o f n a t u r a l l a n g u a g e s y n t a x s h o u l d s e r v e a s a
s t a n d a r d d e f i n i t i o n f o r t h e s y n t a x o f t h e s u b j e c t l a n g u a g e . T h e
s p e c i f i c a t i o n m u s t b e c o m p l e t e , c o n c i s e , c o n s i s t e n t , p r e c i s e , u n a m b i g u o u s ,
u n d e r s t a n d a b l e , a n d u s e f ul t o l a n g u a g e s c h o l a rs , u s e rs , a n d i m p l c m e n t o r s
w h o w i s h t o d e v e l o p a p a r s e r f o r t h e t a n g u a g c t o r u n o n a c o m p u t e r .
F u r t h e r m o r e t h e s p e c i f ic a t io n s h o u l d b e m a t h e m a t i c a l l y r i g o r o u s t o t h e
d e g re e t h a t a n i m p l e m e n t a t i o n o f t h e l a n g u a g e c a n b e a u t o m a t i c a l l y
d e r i v e d f r o m t h e s p e c i f i c a t i o n { 1 0 ] . U n f o r t u n a t e l y m a n y o f t h e s e a i m s a r c
d i f f ic u l t t o a c c o m p l i s h p r i m a r i l y b e c a u s e o f t h e d y n a n r i c a n d i n f o r m a l
n a t u r e o f n a t u r a l l a n g u a g e . F o r m a l s p e c i f i c a t i o n i s s t i l l a w o r t h y g o a l to
t h e d e g re e a l lo w e d b y p r e s e n t k n o w l e d g e a b o u t n a t m ' a l l a n g u a g e a n d i u
t h i s p a p e r w e p r o p o s e a mctalanguage for s p e c if y i n g b o t h s y n t a x a n d
s e m a n t i c s o f n a t u r a l l a n g u a g e t h a t h a s p o t e n t i a l f o r s a t is f y i n g t h es e g o a l s .
T h e m c t a l a n g u a g e w e p r o p o se i s t h e two- l evd grammar [1 6 } (a l s o c a l l e d
W - g r a m m a r s a n d t l gs ) . T w o - l ev e l g r a m m a r s h a v e b e e n u s e d e x te n s iv e l y f o rs p e c if y i n g t h e s y n t a x a n d s e m a n t i c s o f p r o g r a m m i n g l a n g u a g e s [ 2] b u t
t h e i r u se i n s p e c i f y in g n a t u r a l l a n g u a g e w a s f i r s t i n t r o d u c e d b y t h e a u t h o r s
[7 , 8, 9] .
E x i s t i n g f o r m a l s p e c i f ic a t io n m c t h o d s f o r n a t u r a l l a n g u a g e s y n t a x
t a k e m a n y f o r m s . O f t h e s e, s o m e o f t h e m o r e c o m m o n a r e a u g m e n t e d
t r a n s i t i o n n e t w o r k g r a m m a r s [ 1 81 , t r a n s f o r m a t i o n a l g r a m m a r s [ 1] , a n d
g e n e ra l iz e d p h r a s e - s t r u c t u r e g r a m m a r s [ 5] . T h e s e m e t h o d s a n d o t h e r s a r c
a l s o s u r v e y e d i n [ 1 7] . T h e d e g r e e t o w h i c h a n y f o r m a l s p e c i f i c a ti o n m e t h o d
s a t i s f i e s t h e a b o v e s t a t e d g o a l s i s s o m e t i m e s d i f f i c u l t t o e v a l u a t e a n d r e l i e s
o n s u b j e c t i v i t y . T h e a u t h o r s d o n o t i n t e n d t o e v a l u a t e th e s e e x i s t i n g
m e t h o d s w i t h r e s p e c t t o t h e r e q u i r e m e n t s o f f o r m a l s p e c i f i c a ti o n l a n g u a g e s
b u t w i l l i n s t e a d c o n c e n t r a t e o n w h y t w o - l e v e l g r a m m a r s s a t i sf y t h e
n e c es s a ry g o a l s i n a m a t h e m a t i c a l l y r i g o r o u s b u t r e a d a b l e a n d e a s y t o
u n d e r s t a n d w a y . I n t h i s p a p e r , t h e t w o - le v e l g r a m m a r m c t a l a n g u a g e w il l
b e u s e d t o d e f i n e a l a r g e c l a s s i f i c a t i o n o f E n g l i s h d e c l a r a t i v e s e n t e n c e s ,
e x t e n d i n g w o r k d e s c r i b e d i n [ 8 ] a n d [ 9 ] . W e w i l l e m p h a s i z e t h e method ofu s i n g t w o - l e v e l g r a m m a r s f o r t h i s p u r p o s e a n d t h e a d v a n t a g e s g a i n e d
r a t h e r t h a n a n y p a r t i c u l a r c h a r a c t e r is t i c s o f t h e g i v e n g r a m m a r .
2 . T W O - L E V E L G R A M M A R S
A t w o - l e v el g r a m m a r c o n s i s ts o f t w o s e l ) a ra t c g r a m m a r s , t h emstaprodu ctlon rule~ (metarules) a n d t h e hyperrules. T h e m e t a r u l e s a r e
g e n e r a l l y c o n t e x t - f r e e r u l e s w h i c h t a k e t h e f o r m :
M E T A N O T I O N :: h y p c r n o t i o n - 1 ; h y p c r n o t l o n - 2 ; .. . ; h y p e r n o t i o n - n .
w h e r e M E T A N O T I O N i s t il e l e f t- h a n d s i de " n o n t e r m i n a l " s y m b o l o f th e
p r o d u c ti o n a n d h y p e r n o t i o n - 1 , h y p e r n o t l o n - 2 , . . . h y p c r n o t i o n - n a r e t h e n
a l t e r n a t i v e s o f t h e p r o d u c t i o n r i g h t - h a n d s i d e . E a c h h y p c r n o t i o n c o n s i s t s
o f protonotions ( t e r m i n a l s y m b o l s ) a n d o t h e r m e t a n o t i o n s . I n t h e c a se o f
E n g l i sh , t h e t e r m i n a l s y m b o l s o f t h e r e c t a - g r a m m a r a r e E n g l i s h w o r d s.
T h e r e c t a - g r a m m a r i t s e lf is u s e d t o d e f i n c t h e c o n t e x t - f r e e ~ sp c c t s o f
E n g l i s h. E x a m p l e m e t a r u l e s a r c :
S E N T E N C E :: D E T E R M I N E R N O U N V E R B .
D E T E R M I N E R : : a; an; t i l e ; t h e s e ; t h o s e ; t h i s ; t h a t .
U S I N G T W O - L E V E L G R A M M A R
Barrett R . Bryant
D a l e J o h n s o n
B a l a n j a n in a t~ h E d u p u g a n t y
D e p a r t m e n t o f C o m p u t e r a n d I n f o r m a t i o n S c i en c es
T h e U n i v e r s i t y o f A l a b a m a a t B i r m i n g b a m
B i r m i n g h a m , A l a b a m a , U . S . A . 3 5 2 9 4
T h e h y p c r r u l e s a re o f t h e f o r m
h y p c r n o t ] o n ; h y p e r a l t e r n - 1 ; h y p e r ~ l t e r n - 2 ; . .. ; h y p e r a l t e r n - n .
T i le h y p e r a l t e r n a t i v e s s e p a r a t e d b y s e m i c o l o n s a r c d i s t i n c t p r o d u c t i o n
a l t e r n a t i v e s . E a c h o f t h e s e h y p e r a l t c r n a t i v e s m a y b e d i v i d e d i n t o a
s e qu e n ce o f h y p e r n o t i o n s s e p a r a t e d b y c o m m a s . I n a t w o - l e v e l g r a m m a r
d e r i v a t i o n t r e e , t h e r e w i l l b e o n e b r : m c h f o r e a c h c l e m e n t i n t h e s e q u e u c c .
A t w o - le v e l g r a m m a r w i t h e i t h er h y p e r r n l e s h a v i n g m o r e t h a n o n e
h y p e r a l t c r n a t i v e o r t w o d i s t i n c t h y p c r r u l e s h a v i n g t h e s a m e h y p c r n o t i o n
o n t h e p r o d u c t i o n l e f t - h a n d s i d e i s n o n d e t c r m i n i s t i c . [ f c a ch h Y l ) c r ru l e h a s
o n l y o n e h y p e r a l t e r n a t i v e a n d a l l h y p c r n o t i o n s i n p r o d u c t i o n l e f t - h a n d
s i d e s a r e d i s t i n c t f r o m m m a n o t h e r t h e n t h e t l g i s d c t e r m i n i s l ; i c .
A h y p c r r u l e i s a c t u a l l y a p r o d u c t i o n r u l e " p a t t e r n " s i n c e e a c h
h y p e r r u l e c a n p o s s i b l y r e p r e s e n t a n i n f i n i t e n u m b e r o f p r o d u c t i o n r u l e s i n a
c o n t e x t - f r e e g r a m m a r . T h i s i s b e c a u s e e a c h o c c u r r e n c e o f a m e t a n o t i o n i n
t h e h y p c r r u l c r e p r e s e n t s al l se q u e n c e s o f p r o t o n o t i o n s t h a t c a n b e d e r i v c d
f r o m t h a t m e t a n o t i o n . T h a t i s, a h y p e r r u l e m a y b e v ie w e d a s a se t o f
p r o d u c t i o n r u l e s ( c a l l e d strict production rules) i n w h i c h a l l m e t a n o t i o n s
a r e r e p l a c e d b y t h e p r o t o n o t i o n s t h e y d e r i v e . T h e o n l y r e s t r i c t i o n h e r e i s
t h a t i f t h e r e a r c m o r e t h a n o n e o c c u r r c n c e o f a si n g l e r n e t a n o t i o n , t h e n
e a c h i s r e p l a c e d b y t h e s a m e p r o t o n o t i o n s e q u e n c e i n d e r i v i n g t h e s t r i c t
p r o d u c t i o n r u l e s . T h i s i s c a l l e d conM stent substitution. For e x a m p l e , i n t h e
b y p e r r u l c
w h e r e W O R D i s W O R ] ) : t r u e .
b o t h o c cu r r e n c es o f th e m e t a n o t i o n W O R D r e p r ~ e n t t h e s a m e
p r o t o n o t i o n . T h e s e t o f a l l o w a b l e p r o t o n o t i o n s i n t h i s r u l e i s d e f i n ed b y
t h e m e t a r u l c s f o r W O R D . I f t h es e m e t a r u l e s d e f in e a n i n f in i te n u m b e r o f
p o s s i bl e p r o t o n o t i o n s , t h e n t i l e a b o v e h y p e r r u l e a l s o r e p r e s e n t s a n i n f i n i t e
u u m b c r o f s t r i c t i ) r o d u c t i o n r u l e s . [ t i s t i f f s f e a t u r c o f t w o - l e v e l g r a m m a r s
t h a t a l l o w t b c m t o d e f i n e c o n t e x t - s e n s i t i v e a n d r e c u r s i v c l y e n u m c r a b l e
l a n g u a g e s [1 2 ] .
I f c o n s i s t e n t s u b s t i t u t i o n i s n o t r e q u i r e d ( o r d e s i r e d ) f o r m e t a n o t i o n s
w i t h t h e s a m e r o o t m e t a r u l c s ( a n d n a n m ) , t h e n t h e s e m e t a n o t i o n s m a y b e
d i s t in g u i s h e d b y s u b s c r i p t s . F o r e x a m p l e ,
w h e r e S E N T E N C E 1 a n d S E N T E N C E 2 a r e c o r r ec t ;
w h e r e S E N T E N C E 1 i s c o rr e ,c t , w h e r e S E N T E N C E 2 i s c o r r e c t .
I n th i s h y p c r r u l e , S E N T : E N O E 1 a n d S E N T E N C E ~ . a r e d e f in e d b y t h e
s a m e m e t a r u lc s ( a n d r o o t m c t a n o t i o n S E N T E N C E } b u t n e e d n o t h a v e t h e
s a m e i n s t a n t i a t i o n s .
S o m e h y p c r r u l e s c a l l e d predicates a c t a s c o n d i t i o n s w h ic h m u s t b e
s a t i s f i e d fo r t h e d e r iv a t io n t o b e :~ u c ce s sfu l. A p re d i c a t e b e g in s w i th t h e
w o r d w h e r e o r c o a d i t i o n a n d t h e t e r m i n a l d e r i v a t i o n o f t h e h y p e r r u l e i s
t h e e m p t y s t r i n g i f t h e c o n d i t i o n i s s a t i s f i e d a n d w i l l d e r i v e a " b l i n d a l l e y "
( i. e. n o t d e r i v e a n y t e r m i n a l s t r i n g ) i f t h e c o n d i t i o n i s n o t s a t i sf i e d . I n t ir e
t w o - le v e l g r a m m a r o f E n g l i s h p r e s e n t e d i n t h i s p a p e r , a l l h y p e r r u l e s a r c
p r e d i c a t e s a n d s e r v e t o p e r f o r m c o n t e x t c h e c k s s u c h a s s u b j e c t - v e r b
a g r e e m e n t , o b j e c t ~ v c r b a g r e e m e n t , a n d a n y a d d i t i o n a l r e q u i r e d c o n t e x t
c h e e k s w h i c h c a n n o t b e c o n v e n i e n t l y s p e c i f i e d b y a e o n t e x t - f r c e g r a m m a r
( i . e . t i l e mc ta ru l e s ) .
3 . M E T A R U L E S F O R E N G L I S H
T i l e m e t a r u l c s o f t h e t w o - l e v e l g r a m m a r f o r E n g l i s h d e f in e ti r ec o n t e x t - f r e e a ~ p c c t s o f E n g l i s h s y n t* L x. S o m e l e x i c al i t e m s f r o m E n g l i s h c a n
n o t b e e a s i l y d e f i n e d i n a f o r i n a l w a y ( i . e . u s i n g c o n t e x t - f r e e r u l e s ) . T h e s e
i n c l u d e t i l e n o u n s , v e r b s , a d j e c t i v e s , p r o p e r n a m e s , a n d t i t l e s , g i v e n n a m e s
a n d s u r n a m e s f o r p e o p l e w h i c h a r c l c x i c a l c a t e g o r i e s c o n t a i n i n g a l a r g e
n u m b e r o f e l e m e n t s . T h e f o r m a l s p e c i f i c a ti o n o f th e s e c a t e g o r i e s w o u l d b e
p r o d u c t i o n r u l e s o f t l m f o r m :
N O U N : : a a r d v a r k l a b a c u s ; . .. ; z u c c h l n L
V E R B : : a b a n d o n ; a b a t e ; . . .; z o o m .
A D J E C T I V E : : a b d o m i n a l ; a b h o r r e n t i . . 4 z n h c d .
P R O P E R _ N A M E : : A b e r d e e n ; A b i le n c ; .. .; Z a m b i a .
T I T L E : : A d m i r a l ; A r c h b l s l m p ; . .. ; W a r r a n t O f f ic e r.
F o r s i m p l i c i t y w e c h o o s e t o o m i t m o r e f o r m a l s p e c i f i c a ti o n s o f t h e a b o v e
c a t e g o r i e s. A m o r e c o m p l e t e l i s t o f w o r d s i n t h e s e c a t e g o r i e s m a y b c f o u n d
in [14].
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The metarules in our two-level grammar illustrate tile specific subset
of English gra mmar defined in this paper. The subset includes declarative
sentences with the subject noun premed;fled and postmodilled, including
postmodification by relative clauses. The choice of this subset is rather
arbitrary since we have used two-level grammars to define a wide variety
of English sentences (e.g. in [7], more extensive modification is allowed and
also compound sentences). This subset will serve to illustrate the power of
two-level gra mmar s for the purposes of defining English syntax. Because
the notation for metarules follows context-free grammar conventions usingnatural language vocabulary, our recta- gramma r is fairly self-explanatory.
The rules of English syntax that have been incorporated into our grammar
are based on English gr amm ar rules given in [3], [11], [131, and [19].
We now enumera te the metarules used in our two-level grammar of
English. A scntence consists of a noun phrase and a verb phrase. The
noun phrase consists of an optional sentence modifier such as a "viewpoint"
adverbial and a subject sequence. The subject sequence consists of two
main subjects, separated by the coordinator and. The main subjects may
be either a list of nouns premed;fled and postmodified or a proper name
premodificd by a restricter.
1 . SENTE NCE :: NOUN_PH RASE VERB_PItRASE PERIOD.
2 , NOUN_PHRASE ::
SENTENCE_MODIFIER SUBJECT_SEQUENCE.
3 . SENTENCE_MODIFIER :: VIEWPOINT COMMA; EMPTY.
4 , VIEWPOINT :~ artlstlcally; eeonoudeaily; etMcally; financially;
geographically; linguistically; militarily; morally; personally;
politically; psyehologleally; publically; t heoretleally; visually.
5. SUBJECT _SEQUEN CE t:MAIN_SUBJECT; MAIN_SUBJECT and MAIN_SUBJECT.
g. MAIN_ SUBJE CT :.* MODIFIED_N AMED_SUBJ ECT~
PRE_NOUN_MODIFICAT10N NOUN_tIEAD
POST_NOUN_MODIFICATION.
7. MODIFIED_NAME D_SUBJECT ::
RESTRIOTERS NAMED_SUBJECT.
8. NAMED_SUBJE CT ~: PROPER_N AME; GIVEN_NAME~
SURNAME; TITLE SURNAME.
tl . RES TRIO TER S :: chiefly; especially; even; just; largely; mainly;
mostly; primarily; not even; only; EMPTY.
10. NOUN_HEAD :: NOUN; NOUN and NOUN;
NOUNJLIST COMMA_OPTION and NOUN.
11. NO UN_L IST ::
NOUN_LIST COMMA NOUN; NOUN COMMA NOUN.
The verb phrase consists of a predicate sequence and an object
sequence. Tlm predicate sequence consists of an auxiliary seqnence (an
optional auxiliary adverb such as a focusing or maximizing adverb
followed by an activ e or passive auxiliary verb) and the main verb of thesentencc,
12. VERB_PIIRASE ::
PREDICATE_SEQUENCE OBJECT_SEQUENCE.
13. PREDICATE_SEQUENCE :: AUXILIAI?~Y_SEQUENGEVERB.
14. AUX-IL IARY_SEQUENC E t: AUXILIARY ._ADVER B_OPTION ;
AUXILIARY_ADVERB_OPTION
AGTIVE_OR_PAS S IVE~A UXILIARY.
15. AIYXILIARY_ADVERI~_OPTION::AUX]LIARY'~ADVERB; MPTY.
18. AUXILIA RY_ADVE RB ::
FOCUSING_ADVERB; MAXIMIZING._ADVERB.
17. FOCUS ING_A DVER B :: again; also; as we;l; at least; equally;
especially; even; fnrtlmr; in addition; in particular; just; largely;
likewise; mainly; mercly~ mostly; no tably; only; partlcula,'l y!
primarily; principally; purely; purely and slmplyl shnilarly i
simply] specifically.
18. MAXIMIZING_.ADVERB :: absolutelyl al togethe r; completclyl
entirely; fully; in Ml respects; perfectly; qulte; thorough ly;
totally; utterly; very fufiy; very thoroughly.lg. ACTIVE _OR_PASSIVE_AUX ILIARY ~
ACTIVE_AUXILIARY; PASSIVE_AUXILIARY.
20. ACTIVE_AUXILIAR Y :
A1 IXILIARY_. [IAVEAUXILIARY_ADVERB_OP TIC N.
21. PASSIVE_AUXILIARY :
AUXILIARY_BE AUXILIARY_ADVERB_OPTION;
AUXILIARY_J~IAVEAUXILIARY_AD VERB~OPTIO N been.
22. ALVXILIARY_BE :: am~ is; were; was.
23. AUX ILL ~Y_ ItA VE :: have; had; has.
24. AUX ILIARY_V ERB z: AUXILIAR Y_BE; AUXILIA RY_HAV E.
25. AUXILIARY_TRAILER : AUXILIARY_ADVERB_OPTION;
AUXILIARY~aA2)VERB_O PT I O N been .
528
The object sequence of a verb phrase can contain both direct and
indirect objects followed by an optional adverbial such as a maximizing
adverb or a time adverb. Objects can be either a proper name, possibly
modified by the restrieters given above, or a noun expression, possibly
premed;fled and postmodified.
2 6 . OBJECT_SEQUENCE ::
I NDI RECT_OBJECT DI RECT_OBJECT
OB JECT_SEQUENGE_ADVERB;
DIRECT_OBJECT OBJECT_SEQUENCE_ADVERB.27. OBJECT_SEQUENCE ~DV ERB : :
O B JEOT_S EQUENO E~LDVERBIAL; EMPTY.
28. OBJE CT_SEQU ENCE_ADV ERBIAL ::
MAXiMIZING_ADVERB; TIME_ADVERB.
29. TIME_.ADVERB :: again; early; first; last; late; next; now; recently;
simultaneously; slnee; then; today; yesterday.
30. INDIR ECT_ OBJE CT :: OBJEC T.
31. DIRECT_OBJECT :t OBJECT.
32. OBJEC T :: MODIFIED_NAMED _SUBJECT;
PRE_NOUN_MODIFICATION NOUN_HEAD
POST NOUN_MOD1FICATION.
We now turn to the pro-noun-modifiers specified in our grammar. The
modifier is a determiner optionally followed by a list of possessive nouns,
an adjective, a sequence of nouns, another list of possessive nouns and a
denominal noun. Examples of this type of construct include "the
murderer's empty black pistol" and "a very rich man's thick wallet." For
context-sensitive purposes, the determiners are divided into "universal"
determiners which may precede both singular and plural nouns anddeterminers which may only precede singular nouns. Furthermore, a
context-frcc restriction of the pro-noun-modifiers is that thcrc can be at
most one list of possessive nouns in a sequence. For convenienc e we choose
to enforce this condition in the hypcrrules instead of the metarules.
33. PRE_NO UN_MOD IFIOATI ON .' :
DETERMINER PRE_NOUN_MODIFIERS.
34. PRE_NOUN_MOD IFIERS :: EMPTY;
POSSESSM,]_NOUN_LIST AD JEOTIVE_OP TION
NOUN_SEQUENCE POSSESSIVE_NOUN_LIST
I) ENO MINAL_NO UN.
35. D ETER MINER ::
UNIVERSAL_DETERM NER; SINGIJLAR_DETERMINER.
311. UNIVE RSALD ETER MINE R : :
tim; some; any; my; your; his; her; its; our; their.
37. SINGULA R_I)ET ERMINE R :: either i neither; anot her;
NOT_OPTION NEGATABLE_SINGULAR_DETERM[NER.
38. N EGATA BLE_ SINGUL AR_DE TERM INER : a; an; eaeb; every.
39. NOT_OPTION :: not; EMI)TY.40. POSSESSIVE _NOUN_LIST :: EMPTY;
POSSESSIVE_NOUN LIST POSSESSIVE_NOUN.
41. POSSESSIVE_NOUN :: NOUN's; NOU N'.
42. ADJEC TIVE _OPT ION ~: ADJECT IVE; EMPTY.
43. NOUN_SEQUENCE :: NOUN; NOUN and NOUN; EMPTY.
The nouns in the NOUNSEQUENCE denote the physical composition of
items (e.g. "the fisherman's rusted iron hook") and thus act as adjectives
Denominal nouns arc adjectives which denote some quality of the noun
being modified (e.g. "her social life" and "his moral responsibility"). Since
there are a large number of these, we omit their formal specification here.
In our g ramm ar subset we restrict post-noun-modifiers to relative
clauses involving people. Man y othe r forms of post-noun-modificat ion are
ferma l]y specified in [7 ]
44. POST_N OUN_M ODIFIC ATION :: RELATIVE _CLAUSE; EMPTY.
45, RELATIV E_CLAUSE ::
who PREDICATE_SEQUENCE OBJECT_SEQUENCE.
Finally, the punctuation in our gram mar is given below
46. PERIOD :: . .
47. COM MA :t ~ .
48. COMMA OPT ION :: COMMA; EMPTY.
49. EMPTY :: .
4 . HYP ERRUL ES F OR E NGLI S H
The hyperru les of tile two-level gra mm ar for English define the
context-sensitive aspects of English syntax which can not be specified by
the context-free rules ef the recta-gr ammar. Unlike the meta- gramma r, the
hyperrulss do not generate any part of the English sentence. They serve
only to verify the context-sensitive conditions of the grammar. This is
done by using predicates ,~ described earlier. Predicates willderive the
empty string if they are satisfied and will derive nonterminal strings of
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u s e le s s s y m b o l s o t b e r w i s e . T h e n o t i m ~ t h a t t i l e h y p e r r u l c s w i l l n o t
g e n e r a t e a n y t e r m i n a l s t r i n g b u t i n s t e a d v e r i f y c o n t e x t - s e n s i t i v e e o n d i t i o n s
o f a t e r m i n a l s t r i n g a l r e a d y g e n e r a t e d b y t h e c o n t e x t - h 'e e m c t a r u l e s i s a
n n i q u e f e a tu r e o f o u r a p p r o a c h t o d e s i g n i n g t w o -l e v el g r a m m a r s ( e . g . in
c o n t r a s t , s e e [2 ]) . T h i s w i l l g r e a t l y s i m p l i f y p a r s i n g t w o - l e v e l g r a m m a r s a s
w e w i l l s e e l a t e r .
W e w i l l d e fi n e t w o t y p e s o f p r e d i c a t e s . T h e f i r s t o f t h e s e w il l b e
p r e c e d e d b y t h e p r o t o n o t i o n c o n d i t i o n a n d w i l l b e g i v e n e x p li c i t ly i n t h e
f o r m a l g r a m m a r . A s w i t h t h e r e c t a - g r a m m a r , h o w e v e r , t h er e w il l b e s o m e
r u l e s w h i c h c a n n o t b c p r e c i s e l y d e f i n e d i n t h e f o r m a l s y s t e m . T h e s e r u l e s
r e l a t e t o q u a l i t i e s o f t h e u n s p e c i f i e d l e x i c a l e l a s s c ~ ( e . g . n o u n s , v m ' b s , e t c .)
a n d w i l l b e d e s i g n a t e d b y t h e p r o t o n o t i o n w h e r e . F o r e x a l n p l c , t h e
h y p e r n o t i o n s w h e r e N O U N i s s i n g u l a r , w h e r e V E R B i s p a s t p a r t l e l p le ,
a n d w h e r e N O U N a n d V E R B a g r e e in p e r s o n a n d n u m b e r c al l n o t b c
p r e c i s el y d e f i n e d e x c e p t b y a v e r y l a r g e n u m b e r o f f o r m a l r u l e s s u c h m s
t h o s e g i v e n b e l o w :
w h e r e a a r d v a r k i s s i n g u l a r : E M P T Y .
w h e r e a b a n d o n e d i s p a s t p a r t i c i p l e I E M P T Y .
w h e r e A d a m a n d e r e a g r ee in p e r so n a n d n u m b e r : E M P T Y .
I n t h e s u b s e q n e n t d i s c u s s i o n o f h y p e r r u l e s w e w i l l u s e th e n o t , a t i o n I t u
t o d e n o t e h y p e r r u l e n u m b e r n . T h e s t a r t h y p c r r u l e ( I l l ) o f t h e tw o - l e v e l
g r a n u n a r i s :
1 , S E N T E N O E : c o n d i t i o n S E N T E N O E i s a w e l l - f o r m e d s e n t e n c e .
T h i s h y p e r r u l e h a s a s i t s s t a r t n o t i o n a n E n g l i s h s e n t e n c e w h i c h i s w e l l-
f o r m e d w i t h r e s p e c t t o t h e c o n t e x t - f r e e r u l e s o r t h e r e c t a - g r a m m a r f o r
m e t a n o t i o n S E N T E N C E . T h e n e x t h y p e r ru l e ( H 2 ) e x p a n d s t h e s e n t en c e
w i t h r e s p e c t to w h a t c o n d i t i o n s m u s t b e s a t is f i e d . T h e f o r m a l i z a t i o n o f
t h e s e i s s e l f - e x p l a n a t o r y .
2 . c o n d i ti o n S E N T E N ( I E _ M O D I F I E R S U B J E C T _ S E Q , U E N O I g
A U X I L I A R Y _ S E Q U E N C E V E R B O B J E C T _ S E Q U E N C E
P E R I O D i s a w e l l - f o r m e d s e n t e n c e :
c o n d i ti o n S U I 1 J E C ' I ~ S E Q U E N C E s h o w s s u b j e c t -p r e d i c a t e
agreelnent witbA U X I L I A R Y _ S E Q U E N O E VERB,
c o n d i t i o n S U B J E O T _ S E Q U E N O E i.~ a w e l l - f o r m e d s u b j e c t ,
c o n d i ti o n O B J E O T _ S E Q U E N ( J E
s h o w s o b j ee t ~ p r c d ic a t e a g r e e m e n t w i t h V E R B ,
c o n d i ti o n A U X I L I A R Y _ S E Q U ] ' ; N O E V E R B
is ~ w e l l - f o r m e d p r e d i e a t e ~
c o n d i ti o n O B J E G T _ S E Q U E N ( J E i s a w c l b h w m e d o b j e c t .
T h e f i r s t c o n d i t i o n i s t h a t t h e s u b j e c t s e q u e n c e m u s t a g r e e w i t h t h e
p r e d i c a t e s s p e c i fi e d b y t h e a u x i l i a r y s e q u e n c e a n d v e r b . I n o n r g r a m m s r ,
a g r e e m e n t m e a n s t h a t t h e s u b j e c t a n d t h e s u b je c t - v e r b m u s t a g r e e i n
p e r s o n a n d ! m m b c r . T h e r e a r e t w o p o s s i b i l i t i e s fo r s n b j e c t - v e r b s : 1 ) t h e
a u x i l i a r y s e q u e n c e i a e m p t y ( I t 3 ) iu w h i c h c ~ s c t h e m a i n v e r b m u s t b e
c o n s i s t e n t w i t h t h e s u b j e c t , a n d 2 ) t h c a u x i l i a r y s c q u c n c c i s u o n - e m p W
( H 4 ) i n w f i i e h c a s e i t i s t h e a u x i l i a r y v e r b w h i c h m u s t b e c o n s i s t e n t w i t .h
t h e s u b j e c t : S u b je c ~. s m a y b e i n o u r o f t h r e e f o r m s : l ) t h e s u b j e c t i s a
p r o p e r n a m e ( I I 5 ) , p o s s i b l y m o d i f i e d b y a r c s t r i c t c r ( c .g . " e v e n M r . S m i t h "
o r " p r im a r i l y M r s . J o n e s " ) , a n d t h e r e f o r e r e q u i r e s ~ s i n g u l a r v e r b ; 2 ) th e
s u b j e c t i s a s i n g l e s u b j e c t ( H 6 - H T ) i n w b i c h c a s e i t n ee d o n l y a g r e e w i ~h
. t h e s u b j e c t - v e r b ; o r 3 ) t h e s u b j e c t m a y b c a c o m p o u n d s u b j e c t c o -
o r d i n a t e d w i t h a n d ( f I S - I I 9 ) , i n w h i c h c a s c i t r e q n i r e s a p l u r a l v e r l ) ( e .g .
" J o h n an d B i l l ar c h e r e . " ) .
3 . c o n d i ti o n S U B J E C T _ S E Q U E N C E
s h o w s su b j e e t - p r ¢ , d i c a t e a g r e e m e n t w i t h V E R B :
c o n d l t l o n S U B J E O T _ _ S I , , ' Q U I ~ N O E a g r e e s il tl p e r s o n a n d n u t t l b e r
w i t h V E R B .
4 . c o n d i ti o n S U B J E C T S F Q t J E N C I ~
s h o w s r o d ) j e e r - p r e d ic a t e a g r e e m e n t
w i t h A U X I I , I A R Y _ _ A 1 ) V E I t I L O P T I O N A U X [ I , I A R Y V E R B
A U X I L I A R Y _ T R A I L E R V E R B :
c o n d l t k m S U B J E ( J T _ S E Q U E N C E a g r e e s i n p e r s o n a n d n u m b e r
w i t h A I J X [ L I A R Y _ V E R B .
5 . c o n d i t i o n M O I ) I F I E D _ N A M E D _ S U B J E O T
a g r e e s i n p e r s o n a n d n u m b e r w l t h V E R B :
w h e r e V E R B i.q s l n g , d a r .
8 . c o n d i t io n P R E _ . N O U N _ M O D I F I C A T I O N N O U N I 1 E A D
P O S T _ N O U N M O D I F I C A T I O N
a g r e e s i n person and n u m b e r w l t h V E R B :
c o n d i ti o n N O U N _ t t E A D
a g r e e s i n pe r s o n a n d n u m b e r w i t h V E R B .
7 . c o n d i ti o n N O U N ' a g r e c s i n p e r s o n a n d n u m b e r w i t h V E R B :
w h e r e N O L V N a n d V E R B a g r e e i n p e r s o n a n d n u m b e r .
8 . c o n d i ti o n N O U N L I S T O O M M A _ O P T I O N a n d N O U N
a g r e e s i n p e r s o n a n d n u m b e r w i t h V E R B :
w l m r e V E R B i s p h l r a l .
9 . c o n d i ti o n M A I N _ . S U B J E C T I a .n d M A I N _ S U B J E C T 2
a g r e e s i n p e r s o n a n d n n m b e r w l t h V E R B :
w h e r e V E R B i s p l u r M .
T o s a t i s f y t i l e s e c o n d c o n d i t i o n t h a t t i le s u b j e c t o f a s e n t e n c e m u s t b c
w e l l - f o r m e d , t h e s u b j e c t m a y f a l l i n t o o n e o f t h e f o l l o w i n g c a t e g m ' i e s : 1) if
t h e s u b j e c t i s a n a m e ( I I 1 0 ), t h e n i t is a l r e a d y w e l l - f o r m e d b y t h e
m e t a r u l e s ; 2 ) i f t h e s u b j e c t i s m o d i f i e d ( t i l l ) , t h e n t h e m o d i f i e r s m u s t b e
c o r r ec t ; a n d 3 ) if th e s u b j e c t i s a c o m p o n n d s u b j e c t ( I 1 1 2 ), t h e n e a c h
c o m p o n e n t o f th e c o m p o u n d s u b j e c t m u s t b e w e l l -f o r m e d a c c o r d i n g t or u l e s 1 a n d 2 .
1 0 . c o n d i t i o n M O D I F I E D _ N A M E D _ S U B J E C T i s a w e l l - f o r m e d s u b j e c t :
E M P T Y .
1 1 . c o n d i t i o n D E T E I { M [ N E I ) ~ P R E _ N O U N _ M O D I F I E R S
N O U N t l E A I ) P O ST __ N O U N _ _ M O D I F I C A T I O N
is a w e l l - f o r m e d s u b j e c t :
c o n d i ti o n D E T E R M I N E R I ' R E _ N O U N _ M O D I F I E R S
N O U N _ t l E A D i s c o r r e c t in p r e m o d i f i c a t l o n ,
c o n d i ti o n D E T E R M I N E R N O U N _ I l E A l )
P O S T _ N O U N _ M O D I F I ( 3 A T IO N
i s c o r r e c t i n p o s t m o d i f i c a t l o n .
1 2 . c o n d i ti o n I M A I N _ _ S U B J E O T 1 t ro d M A I N _ S I J B J E C T 2
i s a w e l l - f o r m e d s u b j e c t :
c o n d i t i o n M A I N _ S U B J E C T I i s a w e l l - f o r m e d s u b j c c t ,
c o n d i t i o n M A I N _ S U B J E ( J T 2 i s a w e l l - r e m i n d s u b j c c t .
C o r r e c t n e s s o f m o d i f i c a t i o n i m p l i e s t h a t a s u b j e c t m u s t b c c o r r e c tl y
l ) r e m o d il i e d a n d p o s t m o d i f i c d . W e f i r s t g i v e t h e h y p e r r u [ e s w h i c h e n f o r c e
c o r r e c t p r e m o d i f i c a t i o n . P r e m o d i f i e a t i m l ( H 1 3 ) r e q u i r e s 1 ) c o r r e c td e t e r m i n e r u s a g e ( i .e . w i t h r e s p e c t t o s i n g u l a r a n d p l u r a l n o u n s ) a n d 2 )
a n y p r c m o d i f y i n g n o u n s m u s t b e s i n g u l a r o r " m a s s " n o u n s ( i .e . n o u n s
w h i c h d e n o t e i t e m c o m p o s i t i o n s u c h a s a lu m in u m , b ra ~ ss , e t c . ) . A s i n g u l a r
d e t e r m i n e r ( e . g . a, an, each, e t c .) r e q u i re s a s i u g u l a r n o u n ( I l l 4 ) b u t a
" u n i v e r s a l " d e t e r m i n e r ( e .g . so m e , t h e , e t c .) m a y b c u s e d w i t h s i n g u l a r o r
p l u r a l n o u n s ( I I 1 5 ). I f t h e r e a r c n o p r e m o d i f y i n g n o u n s , t h e n h y p e r r u l c
I l l 6 w i l l a p p l y . A s in g l e p r e m o d i f y i n g n o u n ( I I 1 7 ) m a y b c e i t h e r s i n g u l a r
o r a m a s s n o u n . N o t e t h a t r n l e I l l 7 i s n o n d e t e r m i n l s t i c i n t h a t t h e r e a r e
t w o h y p e r a l t e r n a t i v c s . T h e c o n d it . io n i s s a t i s f i e d i f e i t h e r o n c o f t h e s e
h y p c r r u l e s i s s a t i s fi e d . I f t h e p r e m o d i f y i n g u o u n s a r e c o - o r d i n a t e d w i t h an d
( 11 18 ), t h e n b o t h n o u n s m u s t b e m a s s n o r m s ( e .g . " t h e w o o d e n a n d i ro n
d o o r " i s c o r r e c t b u t " t h e f o r e s t a n d g a rd e n p a t h " i s n o t ) .
I a . c o n d i t k m D E T E R M [ N I , ; R P O S S I , ] S S I V E _ N O U N . L I S T t
N O U N _ S E Q U E N C E I ~ O S S I ~ S S I V E _ N O U N _ L I S T 2
D E N O M I N A L _ N O U N N O U N H E A D
lu c o r r e c t i n p r e m o d i f i e a t l o n :
c o n d i t i o n D E T E R M I N E R c o r r e c t l y p r e m od i fi e .~ N O U N I I E A D ,
c o n d i ti o n N O U N S E Q U F N ( ~ E are s i n g u l a r o r m a s s I I [ ) I I [ I S .1 4 . c o n d i t i o n S I N ( ] I J I , A I { _ D E T E R M I N ] I ] R c o r r e c tl y p r e m o d i f i e s N O U N :
w h e r e N O U N i:~ s i n g u b t r .
1 5. c o n di t io n U N I V F R S A b _ D E T E R M [ N E R
c o r re c t ly p r e m o d i f i es N ( ) U N J I E A D : E M P T Y .
1 8 . c o n d i t io n E M P T Y a r e s i n g u b w o r m a s s n o u n s = E M P T Y .
1 7 . c o n d l L io n N O U N a r e s i n g u l a r o r m a .q s n o u n s :
w h e r e N O U N i s M n g u l a ¢ ; w l m r e N O U N i s a m a s s n o u n .
1 8 . c o n d i t i o n N O O N I a n d N O U N 2 a r c s i n g u l a r o r m a s s n o u n s :
w h e r e N O U N 1 i s a m a s s n o u n ~ w h e r e N O U N 2 i s a m a s s n o u n .
l l y p e r r u l c s [ I 1 9 - II 2 7 d e f i n e t h e c o n d i t i o n s f o r p o s t m o d i f i c a t i o n . A n y
p o s t m o d i f i c a t k ) n o f t h e s n b j c c t m a s t b c i n t h e f o r m o f a r e l a t i v e c l a u s e
w h i c h b e g i n s w i t h who. T l i i s t y p e o f r e l a t i v e c l a u s e r c q n i r e s ~ t h u m a n n o u n
a n d t h e v e r b o f t h e r e l a t i v e c l au s e n m s t a g r e e w i t h t h e m o d i f i e d n o u n . F o r
c x a m p l c ~ i u " T h e m e n w h o f ix c o m p u t e r s w e r e v e r y h e l p f u l , " t h e n o u n m e n
n l us t bc }1~ b ll ll l~ gn nO U l l s i nc e i t i s m od i f i e d by w ho a n d t h e v e r b f i x m u s t
b e c o m p a t i b l e w i t h m e n . T b i s t y p e o f re l a t i v e c l a u s e m a y b e c o n s i d e re d a s
d e s c r i b i n g t w o s e p a r a t e s e n t e n c e s : " T h e m e n f i x c o m p u t e r s . " a n d " T h e m e n
w e r e v e r y h e l p fu l . " I n t h e h y p c r r n l e s w h l e h v e r i f y t h e s e c o n d i ti o n s , t h e
s u b - s e n t e n c e d e s c r i b e d b y b hc r e l a t i v e c l a u se i s f o r m e d a n d t h e n c h e c k e d
f o r c o r re c t n e s s u s i n g h y p c r r u l e I 1 2 r c c u r s i v e l y .
1 9. c o nd i t io n I ) E T E R M I N E I t N O U N . _ I I E A D
P O S T N O U N _ . M O D I F I C A T I O N
I S c o r r e c t i l l p o s t l n o d i l | l : a t l o l | l
c o n d i ti o n P O S T _ N O U N M O D I F I O A T I O N
c o r r e c t l y p o st , m o d l f i e s D E T E R M I N E I { N O U N _ [ l E A D .
2 0 . c o n d i t i o n E M P T Y c o r r e c t l y p o s t m o d i f i c s
D E T E R M I N E I { N O U N _ I l E A l ) : E M P T Y .
2 1 . c o n d i t i o n R E L A T I V E _ C L A U S E c o r r e c t l y p o s t m o d i f i e s
D E T E R M 1 N E I '~ N O U N . I IE A D :
c o n d i ti o n N O U N _ I l E A l ) i s a h u m a n n o u n ,
e o n d i t h m t h e v e r b o f R E L A T I V I , ;_ C , L A U S E
a g re e ~ w l tl l I ) E T E R M I N E l l N O U N _ I I E A D .
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22. conditlou N OUN is a human norm t where NOUN is a human noun.
23. condition NOUNI and NOUN2 is a human noun t
wlmre NOUN1 is a hu man noun 9
where NOUN2 is a huma n noun.
24. condition NOUN_LIST COMMA_ OPTION and NOIJN
iS a h L I m a n n o n u 1
condition NO UN_ LIS T in a huma n noun~where NOUN is a human noun.
25. condition NOUN1 COMMA NOUN2 is a human noun :
where NOUN1 ia a human noun 9
where NOUN2 is a huma n noun.
2 { 1 . c o n d i t i o n NOUN_L IST COMMA NOUN is a human noun :
c o n d i t i o n N O U N _ L I S T i s a human noun,
wikere NOUN is a human noun.
27. condition the verb of
who PREDICATE_SEQUENGE OBJECT_SEQUENCE
agrees with DETERMINER NOUN~HEAD :
c o n d i t i o n DETERMINER NOUN_IlEAl)
PREDICATE_SEQUENCE OBJECT_SEQUENCE PERIOD
is a well-formed sentence,
Tile third condition that the English sentences defined by our
gramm ar must satisfy is that the predicate (verb) and objects should agrcc.
The type of verb mast correspoud to the nu mber of objects in the sentence:
if the verb is intransitive, then no objects are allowed except for adverbs
(ti28); if the verb is transiti ve, the n a direct objec t is required (H29); and if
the verb is ditransitive, then both a direct and an indirect object are
required (I130).
28. condition OBJECT_SEQUEN(3E_ADVERB
slmws object"predlcate agreement with VERB :
where VERB is iutransitlve.
29. condition DIRE CT_O RJEC T OBJECT_SE QUENI3E ADVERB
shows object.predlcate agreeme nt with VERB :
where VERB is transitive.
30. condition IND1REC T_ORJE CT DiRE CT_O BJEC T
OB JECT _S E QU EN CIE_A1)VERB
shows object.predlcat e agreement with VERB :
where VERB is dltransltive.
The fourth condition for a well-formed sentence is tha t the auxiliar y
adverbs and m ain verb are in correct gram mati cal sequence, if I,here are no
auxiliary verbs (H31), then tile auxiliary sequence is correct according to
the recta-gr ammar. If auxiliary verbs are present then the verb must be a
past partieiple (II32).
31. condition AUXILIARY_ADVERB _OPTION VERB
is a well-formed predicate : EMPTY.
32. condition ALrXILIAI~Y_ADVEI~,B_OPTION
AC TIVE _OR_ PA S SIVE_,AUX/LIARY VERB
is a well-formed predicate :
where VERB is a past parti ciple.
The fifth and final condition which must be satisfied is fro" the object
of the sentence to be well-formed. A simple object (H33) must satisfy the
same conditions as a subject and hyperrules H10-H12 will apply
recursively. An object sequence (H34) is well-formed if the indirect and
direct objects are well-formed.
33, condition OBJE(3T OBJECT_SEQUENCE_ADVERB
is a well-formed object :
c o n d i t i on O B J E C T i s a well-formed subject.
34. condition INDIRECT_OBJEC IT DIREC T_OB JECT
OBJECT_SEQUEN(3E._ADVERB is a well-formed object :
c o n d i t i o n I N D I R E C V r O B J E ( 3 T i s a well-formed nbject~
c o n d i t i o n D I R E C T _ O B J E C T i s a well-formed object.
It can be seen that the above set of hyperrules is relatively concise and the
conditions being described are readily understandable. We claim that the
other goals of consistency, precision (for our subset of English), and
unambiguity are also achieved. In the next section it will be shown how
this specification may be implemented automatically.
5 . T W O - L E V E L P A R S I N ( I
Our method of natural language specification has two-levcls:
metarules for eontexVfree syntax and hyperrules for context-sensitive
syntax. Similarly our method of parsing a two-level gram mar requires a
parser for metarules and a parser for hyperrules. Since the metarules are
context-free, any of the well-known context-free paining algorithms (e.g.
see [17]) may be used to derive a context-free str ucture of some input
sentence. Context-fre e parsing will elimina te all sentences which do not
satisfy the context-free syntax of the language but is unable to eliminate
530
structures which are correct in the context-free sense but incorrect with
respect to context-sensitive syntax. The hyperrule parser will further reduce
the set of sentences which arc considered to be grammaticall y valid by
analyzing the context-free parse tree for context-sensitive violations.
The "parser" for the hyperrules is actually an interp reter developed by
the authors in [4] which evaluates the hyperrules in much the same way as
a progrannning language interpreter executes programs. The hyperrules
are interpreted sequentially in the order that conditions are enumerated in
the grammar. Interpretation proceeds by expanding the stm't notion and
applying the hyperrules to all of the branches of the hypcrrule derivation
tree until all of the prcdicatcs are evaluated. As interpretat ion proceeds,
each node of the derivation tree (corrcsponding to a hypernotion) is
expanded by matc hing it with a hyperrule lcft-hand sldc. The right-h and
side of the matched hyperrule is then used to create a subtrcc for that
node. Each br anch of tile tree is evalua ted from left to right in a prc~ordcr
traversal. The English sentence is syntactically correct if and only if the
resulting terminal string derived by tbe hypcrrulc tree is the empty string.
The method of writing hyperrules to derive only the einpty string
great ly simplifies th e parsi ng process. Trad iti ona lly (e.g. [2, 10]), ~wo-lcvel
gram mars use tile hyperrules to genera te the termin al s~rings of the
language with the metarules being used only to instantiatc hyperrules. For
example, in our gramma r the metanotion SI°NTENCE is nscd to generate
English sentences which arc tben i n p u t to the hype rrule s for anMysis. In
other two-level grammar styles, however, the components of thc sentence
would also be generated by hypcrrules. The result of hyperrules generating
terminal strings is tha t parsing bccmnes considerably more difficult and is
not accomplished without restrictions being placcd on hypcrrules (e.g. [15]).
Our method of interpre ting hypcrrnles places no restricl, ions, thcrclorc
allowing the tlg to be more gencral. T he differences in writing styles are
cxplored further in I4].
The hyperrule interprctatkm algoritbm is outlined below:
Procedure EvMuute (hypcrnotion)
1. Find tile hyperrule to apply wMch has tim hypernotion as its left.:
hand side. This rule will bc of the form:
hypernoffon : hypernotioa-I, hyperaotfon-2, .. . , hypernoth>u-n.
2. Expand the derivat ion tree with hypernotion tts the root of the
current snbtree ~nd tile branches being hypernvtion-t, hypernolion..2,
, hypernotfon-n.
3. Eval uate (hypernntio n-i) for i ~= 1, 2~ .., n.
To explain how this interpreter works, consider the examplc sentence
"Professor White and the students who attend the university gave Mrs.
White a present today." This sentence is seen to be correct, with respect to
context-free syntax and its structural representation is shown in 1,'ignre 1.
The specific metar ules applied arc numbered . We will now apply the
hyperrules to this sentence to show how the context-sensitive conditions
arc verified. For notational convenience we have italicized the protonotions
which correspond to metanotions in the hyperrules. Since the tree will bc
traversed from left to right we will label the branches (i.e. nodes) using a
nmnber (0-8) to denote the level in the tree and a letter (a-e) to indieaLe
lcf~ to right ordering.
The root of the hyperrulc derivation tree is the sentence itself.
[Iyperrulc HI will be applied to initiate the verification process. This will
be followed by H2 which divides the derivat ion tree into five separate
branches, one for each condition which the sentence must satisfy.
0 • Pro f e s so r W h i t e a n d t h e ~ tu d e n t s w h o a t t e n d t h e u n i v e rs i t y g a v e Mrs .
Wh i t e a p re se n t t o d a y .
1 • condition Pro fe sso r Wh i t e a n d t h e s t u d e n t s w h o a t t e n d t h e u n i v e rs i t y
g a v e Mrs . Wh i t e a p re se n t t o d a y , is a well-formed sentence
2a * condition P r o f e s s o r W h i t e a n d t h e s t u d e n t s w h o a t t e n d t h e u n i v e r s i t y
ghows subject-predicate agreement with gave2b * condition P r o f e s s o r W h i t e a n d t h e s t u d e n t s w h o a t t e n d t h e n n i v e r s i t y is
a well-formed subject
2c • condition a p re se n t t o d a y shows object-predicate agreement with gave
2d * condition gave is a well-formed predicate
2e • condition a p re se n t t o d a y is a well-formed object
To expand branch 2a and cheek the first condition, hyperrule H3 (no
anxiliary verbs) is applied. Since the subject is compound, rule H9 will be
applied, requiring the verb to be plural. The "library" predicate will verify
the plurality of gave .
2a • condition Pro fe sso r Wh i t e a n d t h e s t u d e n t8 w h o a t t e n d t h e u n i v e rs i t y
shows subject-predicate agree ment with gave
3a • condition P r o f e s s o r W h i t e an d t h e s t u d e n t s w h o a t t e n d t h e u n i v e rs i t y
agrees in person and number with gave
4a • where gave is plural
5a •
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t l y p e r r u l e H 1 2 w i l l b e a p p l i e d t o e x p a n d b r a n c h 2 b a n d d e c o m p o s e
t h e c o m p o u n d s u b j e c t i n t o i t s c o m p o n e n t s . I I y p e r r u l e s l t l 0 a n d I l l l w i l l
t he n a na l yz e e ac h o f t he t wo r e spe c t i ve sub - sub j e c t s f o r we l l - fm 'm e dne ss .
2b * c ond i t i on Pro f esso r W h i t e a n d t h e s t u d en t s w h o a t t en d t h e u n i vers i t y
i s a we l l - fo rm e d sub j e c t
3b * c ond i t i on P r o f e s s o r W h i t e i s a we l l - fo rm e d sub j e c t4b *
3c * c ond i t i on t h e s t u d en t s w h o a t t en d t h e u n i vers i t y i s a we l l - fo rm e d
s u b j e c t
4e * c ond i t i on t h e s t u d en t s i s c o r r e c t i n p r e m od i f i c a t i on
4 d . c o n d i t i o n t h e s t u d en t s w h o a t t en d t h e u n i vers i t y i s c o r r e c t i n
p o s t m o d i f i e a t i o n
Proc e e d i ng t o c ons t ruc t t he t r c e i l l a l e f t - t o - r i gh t m a n ne r , b r a nc h 4c i s
e xpa nde d ne x t u s i ng hype r ru l e I t 13 . S i nc e f i l e de t e rm i ne r i s un i ve r sa l a nd
~ he re i s no p re m od i fy i n g noun se que nc e , hypc r ru l e s I t 15 a nd H16 c o m pl e t e
t h i s sub t r e e .
4c • c ond i t i on t h e s t u d en t s i s c o r r e c t in p r e m o d i f i e a t i o n
5b * c ond i t i on th e c o r r e c t l y p r e m od i f i e s s t u d en t s6a •
5 c • c o n d i t io n E M P T Y a r e s i n g u l a r o r m a s s n o u n s
6b *
T h e e x p a n s i o n o f b r a n c h 4 d i s o n e o f t h e m o r e i n t e r e s t i n g a s p e c t s o f
t he c on t e x t - s e ns i t i ve a na l y s i s s i nc e i t i nvo l ve s a r e l a t i ve c l a use . T he
a n a l y s i s i s p e rf o r m e d b y h y p e r r u l e s H I 9 , H 2 1 , t i 2 2 a n d H 2 7 . N o t e t h a tru l e I I27 r e a r r a nge s ~ hc r e l a t i ve c l a use i n t o a ne w se n t e nc e a nd r e e m 's i ve l y
c a l l s hype r ru l e H2 t o a na l y z e t he ne w se n t e nc e .
4d o c ond i t i on t h e s t u d en t s w h o a t t en d t h e u n i vers i t y i s c o r r e c t i n
p o s t m o d i f i c a t i o n
5d • c ond i t i on w h o a t t en d t h e n n i vers i t y c o r r e c t l y pos t m od i f i e s t h e s t u d en t s
6c . c ond i t i on s t u d en t s i s a h u m a n n o u n
7a * whe re ,students is a h l l i l l D . n n o u n
8& •
6d • c ond i t i on t he ve rb o f wh o a t t en d t h e n n i vcrs l t y a g re e s wi t h the
s t u d en t s
7b * c ond i t i on t h e s t u d en t s a t t en d t h e u n i vers i t y , i s a we l l - fo rm e d se n t e nc e
I n s t e a d o f e x p a n d i n g b r a n c h 7 b f u r t h e r , w c w i l l r e s m n e m l r e x a m p l e
a t b r a n c h 2 c t o v e r i f y t h e c o n d i t i o n t h a t t h e o r i g in M s e n t en c e m u s t h a v e
ob j e c t -p re d i c a t e a g re e m e n t . S i nc e t he ob j e c t se que nc e c on t a i n s a n i nd i r e c t
ob j e c t , d i r e c t ob j e c t a nd a n a dve rb , hype r ru l e H30 wi l l be Nl p l i e d ne x t a nd
s i nc e t he ve rb gave i s d i t r a n s i t i v e , o b j e c t - p r e d i c a t e a g r e e m e n t w i l l h e
sa t isf ied.
2e * c ond i t i on M rs . W h i t e a p resen t t o d a y s h o w s o b j e c t - p r e d i c a t e
a g r e e m e n t w i t h cave
3d * whe re gave i s d i t r a n s i t i v e
4e •
Re t u rn i ng t o t he t op - l e ve l c ond i t i ons , we ne x t ve r i fy t he we l l -
fo rm c dne ss o f t he ve rb gave. Si nc e t he re a r c no a ux i l i a ry ve rbs , hypc r ru l e
l t31 is sa t i sf ied.
2d • c ond i t i on gave i s a we l l - fo rm e d p re d i c a t e
3e •
T he f i na l c ond i t i on t ha t t he se n t e nc e m us t sa t i s fy i s we l l - fo rm c dn e ss of t he
ob j e c t . S i nc e the ob j e c t i s a se que nc e , r u l e H34 wi l l be a pp l i e d t o b r a nc h 2c
t o de c om pose t i l e ob j e c t se que nc e a nd a na l yz e the i nd i r e c t a nd d i r e c t
ob j e c t s i nd i v i du a l l y by ru l e H33 . Ru l e I t a a c a l l s r u l e s I I10 - I I12 r e cu r s i ve l y .
S i nc e Mrs. Whi te i s a na m e d sub j e c t , hype r ru l e H10 i s sa t i s f i e d fo r t i l e
i nd i r e c t ob j e c t . By a pp l y i ng hypc r ru l e s [ I11 , II13 , HI4 , H16 , I t 19 a nd 1120 ,
t he d i r e c t ob j e c t a p r e s e n t wi l l a l so be ve r i f i e d a s a we l l - fo rm e d ob j e c t . T he
a n a l y s i s i s n o w c o m p l e t e a n d t h e s e n t e n c e h a s b e e n d e t e r m i n e d t o b e
c o r r e c t t h r o u g h t i l e p r o c e s s o f o u r t w o q e v e l g r a m m a r i n t e r p r e t a t i o n
m e t h o d .
6 . C O N C L U S I O N S
W e h a v e s h o w n t h a t t w o - l e v e l g r a m m a r s m a y b e u s e d v e r y e l e g a n t l y
t o g i ve a fo rm a l spe c i f i c a t i on o f Igng l i sh c on t e x t- f l ' e c a nd c on t e x t - se n s i t i ve
s y n t a x . I n a d d i t i o n t o t h e s u b s e t w e h a v e d e f i n e d i n t h i s p a p e r , m a n y
o t he r t ype s o f Nn g l i sh de c l a r a t i v e se n t e nc e s ha ve be e n fo rm Ml y spe c i f i e d
us i ng t wo- l e ve l g r a m m a rs {7 ]. T he re se e m s t o be no obs t a c l e t o u s i ng r i g
spe c i f i c a t i ons fo r a ny t yp e o f na t u ra l l a ng ua ge syn t a c t i c spe c i f i c a t i on .
T i l e p r i n c i p a l a d v a n t a g e s o f t h e t w o - l e v e l g r a m m a r m c t M a n g u a g e a r e :
1 ) it i s v e ry r e a d a b l e a n d m a y b e u s e d t o g i v e a f o r m a l d e s c r i p t io n u s i n g a
s t r u c t u r e d f o r m o f n a t u r a l l a n g u a g e ; 2 ) i t i s f o r m a l w i t h m a n y w e l l - k n o w n
m a t h e m a t i c a l p r o p e r ti e s ; a n d 3 ) i t i s d i re c t l y i m p l c m e n t a b l e b y
i n t e r p r e t at i o n . T h e s i g n i f ic a n c e o f t h e l a t t e r f a c t i s t h a t o n c e w e h a v e
w r i t t e n a t w o - l e v e l g r a m m m ' f o r n a t u r a l l a n g u a g e s y n t a x , w e c a n d e r i v e ap a r s e r a u t o m a t i c a l l y w i t h o u t w r i t i n g a n y a d d i t i o n a l s p e c i al i z ed c o m p u t e r
p r o g r a m s . T h e c o m b i n a t i o n o f r e a d a b i l i t y a n d i m p l e m e n t a b i l i t y i s u n i q u e
i n g r a m m a r t h e o r y f o r n a t u r a l l a n g u a g e s .
T o g i v e a c o m p l e t e s p c c i f ic a t io n o f n a t u r a l l a n g u a g e , s e m a n t i c s a n d
k n o w l e d g e re p r e s e n t a t i o n m u s t b e s p e c i f ie d in a d d i t i o n t o s y n t a x . O u r
f u t u r e g o a l s a re t h e i n v e s t i g a t i o n o f t w o - le v e l g r a m m a r f o r s e m a n t i c
spe c i f i c a ti on . Be c a use o f t he e a se wi t h wt f i c h t wo- l e ve l g r a m m a rs m a y
e xpre ss l og i c [6 ] a nd t he i r T u r i ng c om pu t a b i l i t y [12 ] , we e xpe c t t ha t t l g s
wi l l a l so bc ve ry su i t a b l e fo r t he se goa l s .
REFERENCES
I l l C h o m s k y , N . S yn t a c t i c S t ru c t u res . M o u t o n P u b l i s h e r s , T h e t I a g u e ,
Ne t he r l a nds , 1957 .
[2] Gl e a ve l a nd , J . C . a nd U z ga l i s , R . C . G r a m m a r s / o r P r o g r a m m i n g
Languages. E l s e v i e r N o r t h - I I o l la n d , N e w Y o r k , 1 97 7 .
[3] Cu l i c ovc r , P . W. S y n t a x . 2 n d e d . A c a d e m i c P r e s s , N e w Y o r k , 1 98 2 .
I4 ] E d u p u g a n t y , B . a n d B r y a n t , B . R . " T w o - L e v e l G r a m m a r s f o r
A u t o m a t i c I n t e r p r e t a t i o n . " P r c c . 1 9 8 5 A C M A n n u a l C o n fe r e nc e ,1985, pp. 417-423.
[5 ] Ga z c l a r , G . a nd Pu l l um , G . K . Gen era l i zed Ph ra se S t ru c t u re
Gra mm a r: A Th eo re t i ca l S yn o p s i s . I n d i a n a U n i v e r s i t y L i n g u i s t i c s
C l u b , I n d i a n a U n i v e r s i t y , B l o o m i n g t o n , I n d . , 1 9 8 2.
[ 6] t l e ss c , W , " A C o r r e s p o n d e n c e I le t w e e n W - G r a m m a r s a n d F o r m a l
S y s t e m s o f L o g ic a n d I t s A p p l i c a t i o n t o F o r m a l L a n g u a g e
De sc r i p t i on ." C o mp u t . L i n g u i s t . C o mp u t . La n g . 1 3 (1979), 19-30.
[7] John son, D. U s in g T w o - L e v d G r a m m a r s t o D e s c r i be t h e S y n t a x o f
English. M . S . T h es i s , D e p a r t m e n t o f C o m p u t e r a n d I n f o r m a t i o n
S c ie nc es , T h e U n i w ; r s i t y o f A l a b a m a a t B i r m i n g h a m , 1 98 4 .
[8 ] J o h n s o n , D . an d B r y a n t , B . R . " U s i n g T w o - L e v e l G r a m m a r s t o
D e s c r i b e t h e S y n t a x o f E n g l i s h . " P a p e r s o n C o m p u t a t i o n a l a n d
C o g n i t i ve S c i en ce , e d. E . B a t t i s t e l l a . I n d i a n a U n i v e r s i t y L i n g u i s t ic s
C l ub , B l oo m i u g t m b had . , Aug . 1984 , pp . 61-86.
[91 J o h u s o n , D . a n d B r y a n t , B . R . " F o rm M S y n t a x M e t h o d s f o r N a t u r a lL a n g u a g e . " [nf ])rocess. Let t . 19, 3 (Oct . 1984) , 135- .143.
[1O] Pagan, F . G . F o r m a l S p e c i fi c a t i o n o f P r o g r a m m i n g L a n g u a g e s : A
P a n o r a m i c P r i m e r . Pre n t i c e -H a l l , E ng l e woo d C l if f s, N . J . , 1981 .[11] Qu i rk , R . e t a l , A Gra m ma r o f Oo n t em p o ra ry En g l i sh . L o n g m a n ,
Wh i t e P l a i n s , N . Y . , 1972.
[ t2 ] S i nt T , f f, M. "E x i s t e nc e o f w m W i j ng a a rd e n ' s Syn t a x fo r E ve ry
R e c u r s i v e l y l g n m n e r a b l c S e t . " A n n . S o s . S e t . B r u x d l c s 2 (1967), 115-
118.
[13] Stagcbcrg, N . C . A n I n t r o d u c t o r y E n g l i s h G r a m m a r . 4 t h e d . Ho l t ,
R i n e h a r t a n d W i n s t o n , N e w Y o r k , 1 9 8 1.
[141 W eb s t er ' s Th i rd N e w In t ern a t i o n a l D i c t i o n a ry , Un a b ri d ged . Th e Grea t
L i b ra ry o f t h e En g l i sh La n g u a g e . M e r r i a m - W e b s t e r , S p r i n g f i e h l ,
Ma.ss., 1981.
[15] We gn e r , L . M. "On Pro ' s i ng T wo-L e ve l Gra m m a rs ." A c t s I n f . 1 ~
(1980), 175-193.
[ 16 ] v a n W i j n g a a r d e n , A . " O r t h o g o n a l D e s i g n a n d D e s c r i p t i o n o f a F ro ' r ea l
L a n g u a g e . " T e c h n i c a l l { e p o r t M R 7 6 , M a t h e m a t i s e h C e n t r u m ,
A m s t e r d a m , 1 9 6 5 .
[17 ] Wi nogra d , T . N a t u ra l La n g u a g e a s a C o g n i t ive Pro cess . Vo l u me b
S yn t a x . A d d i s o n - W e s l e y , R e a d i n g , M a s s . , 1 9 8 3.
[ 18 ] W o o d s , W . A . " T r a n s i t i o n N e t w o r k G r a m m a r f o r N a t u r a l L a n g u a g eA n a l y s i s . " C o m m u n . A C M 1 3 (1970) , 591-602.
[19 ] Z a ndvoor t , R . W . A I I a n d b o o k o f E n g l i sh G r a m m a r . P r e n t i c e - f l a i l ,
Eng lcwo od Cl iffs, N. J . , 1965.
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