* o r verb phrases such as "there is" - quite pos- sibly the only "real" existential quantifier English has... Without additional sources o£ quantification a considerable proportion o£ r
Trang 1M i c h a e l H e s s
U n i v e r s i t y o f Z u r i c h , S e m i n a r o f G e n e r a l L i n g u i s t i c s , Plattenstrasse 54, C H - 8 0 3 2 Z u r i c h , S w i t z e r l a n d
A B S T R A C T
It has traditionally been a s s u m e d that Natural
L a n g u a g e uses explicit quantifier expressions
(such as "all" a n d "most", "the" a n d "a") for the
p u r p o s e of quantification W e argue that expressi-
ons of the first type are comparatively rare in
real world Natural L a n g u a g e sentences, a n d that
the latter (articles) cannot be considered stra-
ightforward quantlfiers in the first place H o w -
ever, practically all applications of Natural
L a n g u a g e Processfng require sentences to be
quantified unambiguously W e llst a few possible
( syntactical, semantical, a n d "pragmatical") sour-
ces of "implicit" quantiflcatlonal information in
Natural L a n g u a g e ; they combine in sometimes
intricate w a y s to give a sentence a (more or less)
u n a m b i g u o u s quantification
i T H E L A C K O F E X P L I C I T Q U A N T I F I C A T I O N IN
N A T U R A L L A N G U A G E
- " I i I N T R O D U C T I O N
T h e s u b j e c t o f t h e p r e s e n t p a p e r is n o t s t r i c t l y
o n e of C o m p u t a t i o n a l L i n E u i s t i c s N e i t h e r d o e s i t
o u t l i n e a w o r k i n g c o m p u t e r p r o g r a m , n o r i n v e s t i -
g a t e a linguistic problem with the help of c o m p u -
tational methods A/though the subject m a y be
p u r e l y linguistic in c h a r a c t e r it is p a r t i c u l a r l y
r e l e v a n t to C o m p u t a t i o n a l L i n g u i s t i c s M o r e o v e r it
seems t o have been ignored b y most non-computa-
tional linguists
Computational as well as non-computational
linguists agree that w e have to represent Natural
L a n g u a g e sentences as quantified logical senten-
ces, either in a graphical variant of logic such as
semantic networks, or in some other form of
logic However, non-computational linguists do
not very often use real-world examples in their
investigations; they create their o w n example sen-
tences to m a k e a certain point Everything which
is not in the prhnary focus of their interest is
m a d e so explicit as to b e c o m e largely self-expla-
natory T h e y tend, for instance, to create only
sentences w h e r e quantification is explicit C o m -
putational linguists, on the other hand, have to
use real world texts T h e y have to face certain
nasty facts of life which they, too, w o u l d prefer
to ignore O n e of t h e m concerns the w a y in w h i c h
Natural L a n g u a g e quantifies
1.2 T H E T R A D I T I O N A L P O I N T O F VIEW:
Q U A N T I F I E R S A R E E X P L I C I T Traditionally it has almost always been a s s u m e d that quantification is expressed in Natural L a n g u - age b y explicit means T h e most traditional view
h a d it that simple surface w o r d s correspond one- to-one to the two classical quantifiers: "every"
a n d "all" stand for the universal quantifier,
"some" for the existential quantifier:
e v e r y man is m o r t a l
s o m e g o d s a r e m o r t a l
H o w e v e r , it has long b e e n k n o w n that the over-
w h e l m l n g majority of real world sentences simply don't contain a n y of those explicit simple quanti- fier words.* For this reason ( a m o n g others) Bar- wise a n d C o o p e r (1981) suggested that the con- cept of simple quantiflers should be e x t e n d e d to the concept of- gemern]|~ed quant/fiers T h e y should take care of simple cases such as most m e n
as well as of v e r y complicated ones such as m o r e than half of John's arrows A generalised quanti- fer consists, in English, of a determiner (such as
most or more than half of ) a n d a set expres- sion in the form of a n o u n phrase (such as "men"
or "John's arrows") Determiners are some,
e ' ~ e ~ , each, all, both, no, n e i t h e r , m a n y , fev;, most, a f e w , one, e t c H o w e v e r , e v e n n o w a
s i z e a b l e m a j o r i t y o f s e n t e n c e s in a n y r e a l w o r l d text w o u l d appear to lack quantification That's
w h y the most obvious determiners, viz the a n d
a (plus zero) h a v e to be included in this list
B u t that's also w h e r e a n e w set of problems origi- nates Articles have always caused problems
w h e n treated as quantifiers, a n d recently these problems have b e c o m e increasingly' more difficult
to ignore ( K a m p 1981)
1.3 P R O B L E M S W I T H T H E I N T E R P K E T A T I O N O F
A R T I C L E S A S Q U A N T I F I E R S
A g a i n we s t a r t w i t h t h e m o s t t r a d i t i o n a l v i e w of
t h e q u e s t i o n h o w a r t i c l e s c o u l d b e i n t e r p r e t e d a s
q u a n t i f i e r s I t s a w b o t h d e f i n i t e a n d i n d e f i n i t e
a r t i c l e s a s e x i s t e n t i a l q u a n t l f i e r s , w i t h some a d d i - Uonal i n f o r m a t i o n i n t h e c a s e of t h e d e f i n i t e
a r t i c l e I t w a s p r i m a r i l y t h i s " a d d i t i o n a l i n f o r m a -
t i o n " w h i c h c a u s e d m u c h d i s c u s s i o n
* o r verb phrases such as "there is" - quite pos- sibly the only "real" existential quantifier English has
Trang 2I 3 i Is the Definite Article an Existential
Quantifier?
Russell, in his classical analysis o f the definite
article (1905), maintained that a sentence such as
1) T h e President of France is bald
should be interpreted as follows
E X I S T S X: (president_of_frence(X) A N D
N O T ( E X I S T S Y: (presidant_of_frence(Y)
A N D N O T ( X = Y ) ) ) A N D bald(X) )
Here the "additional information" is given in the
universal statement that X is t h e one and only
President of France Strawson (1950) pointed out
that sentences such as 2
2) T h e king of France is bald
wou/d simply be false irrespective of w h e t h e r a)
there w a s exactly one king of France but he w a s
not bald, b) there w a s no king of France to
begin with, or c) there were several kings of
France O u r intuition tells us that in case a)
sentence 2 would certainly be "simply false" but
in cases b) a n d c) it would be false "in a diffe-
rent way" Strawson a r g u e d that Russell hadn't
m a d e the distinction between a sentence as such
a n d the statement m a d e b y the use of a sentence
Sentences such as example 2, uttered at the pre-
sent time, a n d u n d e r condition a), were non-eva-
luable (not Strawson's term) rather than false
T h e y m a y be evaluable, a n d e v e n true, at other
points in time (or space, w e might add) A defi-
nite n o u n phrase, then, does not assert the exi-
stence of some object, it only refers to it, a n d in
doing so it presupposes its existence In the same
sense it doesn't assert the uniqueness of the
object referred to, either, it only presupposes it
Unfulfliled presuppositlons don't m a k e sentences
false, they m a k e them" non-evaluable, i.e the
question of w h e t h e r they are true or false doesn't
arise W h e t h e r the presuppositions of such a
sentence are fulfilled d e p e n d s on the concrete
circumstances, given b y the context
Subsequently it w a s noticed that Strawson's
analysis gave no satisfactory explanantion for
cases such as 3, 4 a n d 5:
3) T h e unicorn is a mythical creature
4) T h e lion is a dangerous animal
5) T h e d o g is barking
In 3 w e certainly don't presuppose the existence of
unicorns, but the sentence m a k e s nevertheless
perfect sense 4 is actually the same case
although the fact that lions do exist m a y obscure
this fact at first W e obviously presuppose the
existence of the concept of unicorns and lions in
the listener's mind, but not the existence of these
animals in the real world
Example 5 shows that definite n o u n phrases
don't presuppose uniqueness of real objects,
either 5 m a k e s perfect sense, in the appropriate
context, but n o b o d y would presuppose that there
is only one dog in the world T h e suggestion
that w e could temporarily restrict the universe of
discourse to the point that it contains only one
dog, precisely the one that is barking, is hardly
very convincing on intuitive g r o u n d s alone, a n d
furthermore M c C a w l e y (1981:265) pointed out that
w h i c h they definitely are not
6) The clog likes all dogs
6a) The dog likes itself
It might be more appropriate to talk about uni- queness in a contextual domain ( M c C a w l e y 1981:265, e x p a n d i n g on Karttunen 1976; also Plat- teau 1980, K a m p 1981, Frey/l%eyla 1983) w h o s e
m e m b e r s are created b y the context, a n d are not necessarily elementary real world objects (as in the universe of discourse) but can be sets of real objects, or possibly even purely notional objects such as concepts
A s the problems of definite reference are treated in-depth elsewhere in this volume ( B e r r y - R o g g h e ) w e will restrict ourselves to this
v e r y sketchy outline of the problem T h e main point in this context is that a n y notion of the definite article having an existential quantifier as one of its components has evaporated along the
w a y from Russell's analysis to contemporary views Without additional sources o£ quantification
a considerable proportion o£ real world sentences would n o w appear to be merely un-quantified, meanlngless, expressions, which they certainly aren't B u t it gets even worse
I 3.9 Is the Indefinite Article an Existential
Quantifier?
T h e indefinite article seems, on the surface, to cause m u c h less trouble than the definite article Its interpretation as an existential quantifier always looked quite straightforward H o w e v e r , it
w a s noticed ( K a m p 1981) that indefinite articles sometimes m u s t be represented as universal q u a n - riflers Prominent a m o n g these cases are the so- called d o n k e y sentences, exemplified b y sentences
7 a n d 8
7) If P e d r o owns a d o n k e y he is rich
8) If P e d r o owns a d o n k e y he beats it
T h e trsditlonal, a n d most natural, representation
of 7 is 7a 7a) E X I S T S X: ( d o n k e y ( X ) A N D owns(pedro,X))
IMPLIES rich(pedro)
w h e r e the top-most syntactic connector of the English sentence, i.e the conjunction "if", cor- responds to the top-most connector of the logical form, i.e the implication H o w e v e r , if w e apply the same schema mechanically to example 8 it will produce the non-sentence 8a:
8a) E X I S T S X: ( d o n k e y ( X ) A N D owns(pedro,X))
IMPLIES beats(pedro, X)
This is not a logical sentence because the variable
"X" in the consequent is outside the scope of the existential quantifier a n d remains u n b o u n d 8 must therefore be represented as 8b
8b) A L L X: ( ( d o n k e y ( X ) A N D owns(pedro,X))
IMPLIES beats(pedro, X))
w h e r e the indefinite article is n o w represented as
a universal quantifier N o w w e are in the most unsatisfactory situation that w e have to represent two s~rntactically very similar surface sentences
b y two radically different logical sentences, a n d that the same n o u n phrase has to be m a p p e d into
9
Trang 3quantifier another time
If w e try to consistently represent indefinite
articles as universal quantfflers w e get 7b as
representation for 7
7b) ALL X: ( ( d o n k e y ( X ) A N D o w n s ( p e d r o , X ) )
IMPLIES r i c h ( p e d r o ) )
w h i c h is indeed logically equivalent to 7a, but on
purely formal grounds T h e scope has b e e n artifl-
c i a l l y e x t e n d e d to s p a n o v e r t e r m s w i t h o u t a n y
v a r i a b l e s , w h i c h c e r t a i n / y r u n s v e r y much a g a i n s t
o u r i n t u i t i o n a b o u t t h e m e a n i n g of t h e o r i g i n a l
s e n t e n c e T h e c o n c l u s i o n c a n n o t b e a v o i d e d t h a t
e v e n the seemingly innocuous indefinite article
cannot be represented as a straightforward exi-
stential quantifier
i 4 C O U N T E R E X A M P L E S : M O S T Q U A N T I F I ~ R S
A R E IMPLICIT
H o w e v e r , if articles are no longer available as
explicit quantiflers w e are in real trouble: Either
all those Natural L a n g u a g e declarative sentences
that do not contain a n y of the explicit quantifier
expressions ("most", "some", "there is" etc.)
cannot be represented as logical sentences at all
for their lack of quantification, or else w e h a v e
to find sources of ciuantiflcatlonal information
other than explicit quantifier expressions N o w , if
w e look at sentences 9 to 14 w e have to admit a)
that they are reasonably normal sentences, b)
that they contain no explicit quantifier expressi-
ons, a n d c) that our intuition tells us neverthe-
less that they are u n a m b i g u o u s l y quantified
9) A d o g is eating meat
10) A d o g eats meat
10a) D o g s eat meat
I i ) A man w h o l o v e s a w o m a n i s h a p p y
1 2 ) A m a n w h o l o v e s a w o m a n r e s p e c t s h e r
1 3 ) A m a n w h o l o v e s a w o m a n w i l l E l v e h e r a r i n g
1 4 ) A man w h o l o v e s a w o m a n w i l l d e f e n d h e r
ag-ln~t a n a t t a c k e r
W e think, therefore, a n d try to s h o w in this
paper, that there m u s t be m a n y m o r e sources of
quantificatlonal information in N L than ]ust the
traditional, explicit, cases B u t the information is
scattered over whole sentences, or e v e n para-
graphs, a n d must be combined to get a (more or
less) reliable quantification for a sentence
This is a rather unattractive state of affairs:
Traditionally, it w a s a s s u m e d that at least the
form of quantifiers in hrL sentences w a s unproble-
matical, a n d that w e could concentrate right a w a y
o n the questions of their scope, monotonlcity
etc., difficult e n o u g h in their o w n right If our
diagnosis is correct, this is not so In the rest of
the paper w e will try to list some of the other
possible sources of quantiflcational information in
NL N o n e of t h e m will be of the "on/off"-variety;
they are all more llke interacting forces resulting
in a net force tipping the balance one w a y m r the
other W e will go t h r o u g h all the examples listed
above, considering slightly more complex cases as
w e go along, a n d try to s h o w h o w different these
seemingly similar examples ~really are as far as
their quantif~cati0n is concerned
• i
2
2.1
S O U R C E S O F IMPLICIT Q U A N T I F I C A T I O N IN
N A T U R A L L A N G U A G E
S Y N T A C T I C M E A N S T O E X P R E S S
Q U A N T I F I C A T I O N
2 1 I V e r b a l F o r m
T h e most important w a y to determine the quantifi- cation of a sentence b y syntactic • m e a n s is
t h r o u g h the choice of the v e r b form This beco-
m e s particularly clear w h e n w e look at examples 9
to 10a T h e y are striking cases in that 9 is a prototypical case of an assertion about an indivi- dual event a n d 10 a n d 10a are equally prototypi- cal universal ~ules H o w e v e r , it could be a r g u e d that the mass n o u n u s e d ("meat") unnecessarily complicates the situation So let's replace t h e m with the perfectly regular examples 15 to 18.2 15) A text editor makes modifications to a text file
16) A text editor is making modifications to a text file
17) A text editor made modifications to a text file
18) A t e x t e d i t o r has made m o d i f i c a t i o n s t o
a t e x t f i l e
In example 15 w e say that a text editor m a k e s modifications to a text file in general, almost b y deflnltion W e might read t h i s sentence in a system manual In 16 to 18 w e say, on the other hand, that there is, or was, a case of a text editor m a k i n g modifications to a text file T h e s e
r e m a r k s might be m a d e b y a system operator, watching his screen In 16 to 18 w e express, of course, additional information about the temporal relationships involved, but w e will ignore t h e m in the present context, a S w e e p i n g u n d e r the carpet the question of h o w w e w o u l d have to represent the sentence predicate w e could, as a very first approximation, represent the example with the
v e r b in the present tense, 15, as 15a a n d the examples with verbs in either the past tense or in the perfective or progressive aspect, 16 t h r o u g h
18, as 16a:
15a) A L L T: (text_edltor(T) IMPLIES makes_modlfications (T)) 16a) E X I S T S T:(text_editor(T)
A N D makes_modifications (T))
W e must q u a l i f y these statements at once
I In m a n y cases the future tense is prefer- red over the present tense for the kind of general statements given in example 15 19
is definitely more acceptable than 20:
1 9 ) A man w h o l o v e s a w o m a n w i l l s t r o k e
h e r
20) A m a n w h o loves a w o m a n strokes her
2 Here, a n d in all the other examples used, the indefinite singular could be replaced b y the plural without a n y change in quantification W e
will , f o r r e a s o n s of s i m p l i c i t y , u s e o n l y s i n g u / a r
e x a m p l e s
Trang 4to call for the future tense, w h e r e a s static
verbs, such as "to respect", s e e m to go
better with the present tense T h e reason
for this seems to be that static verbs do
not require the future tense to express
their p e r m a n e n t validity, as their very
meaning as verbs of disposition etc
already conveys t h i s connotation M a n y
other verbs go either with the present or
with the future tense: " O i l floats on
water" is as acceptable as "Oil will float on
water"
2 T h e past tense can express a universally
quantified assertion, as in " A student read
books w h e n I w a s young", contrary to
w h a t w e said above H o w e v e r , for this
universal quantification to be possible the
sentence requires a spatial or temporal
postmodifier, as the one printed in italics
T h e universal quantification is then not
contributed b y the verbal form but rather
b y the postmodifier; the present tense of
the verb merely admits it
3 T h e progressive aspect can express unl-
versa/ quantification, as in "John is always
coming late" Again, thls is only possible
it the quantification proper is contributed
,~alulte explicitly b y phrases such as
ways", "in general", "regularly" etc
T h e sentence is more emotional than the
version in the present tense
Ignoring all these exceptions w e can formulate the
tentative rules i%1 a n d 1%2 to s u m u p w h a t the
examples considered so far seem to suggest
1%1) T h e subject of a sentence is
existentially quantified if the V P is
I in the past tense,
2 in the progressive aspect, or
3 in the reflective aspect
1%2) Otherwise the subject Is universally
quantified, in particular ff it is
1 in the present tense or
2 in the future tense
3 See des T o m b e et al., this volume, for a tho-
r o u g h treatment of the problems connected with
the representation of temporal information
2.1.2 R e s t r i c t i v e Constructions
O n c e w e h a v e determined the quantification of the sentence subiect w e h a v e to do the same thing for all other sententlal components E x a m p l e s Ii a n d
12 for instance, repeated here for convenience, 11) A m a n w h o loves a w o m a n is happy
12) A m a n w h o loves a w o m a n respects her
are variants of the donkey-sentences quoted
a b o v e (7 a n d 8) T h e r e w e h a d the problem that the object of the restrictive relative clause ("a
d o n k e y " ) h a d to be quantified existentially in the first case, a n d universally in the second, syntac- tically v e r y similar, case Analogously, w e m u s t
n o w determine h o w "a w o m a n " is to be quantified Again, intuition tells us that it is to be quantified existentially in example ii but universally in example 12 H o w e v e r , h o w could w e derive this fundamentally different quantification from the syntactically similar surface sentences?
It's an intriguing observation that a simple
c h a n g e in notation will m a k e the problem go away Instead of the Predicate Calculus representation lla a n d 12a with their different explicit quanti- fiers
lla) A L L M: (man(M) A N D E X I S T S W: ( w o m a n ( W )
A N D loves(M, W)) IMPLIES h a p p y ( M ) ) 12a) A L L M : ( m a n ( M ) IMPLIES (ALL W : ( w o m a n ( W )
A N D loves(M,W)) IMPLIES respects(M,W))
w e represent 11 a n d 12 in Horn-Clause logic as llb a n d 12b:
U b ) h a p p y ( M ) : - m a n ( M ) , w o m a n ( W ) , loves(M,W) 12b) respects(M,W) :- man(M), w o m a n ( W ) ,
loves(M, W)
U n d e r the standard interpretation of Horn-clauses (as in Prolog) a variable is implicitly universally quantified if it appears on the left h a n d side of a clause, but existentially quantified if it appears exclusively on the right h a n d side T h e intere- sting fact is that the Horn-clause representations
of the surface sentences are structurally as simi- lar to each other as the surface sentences are,
a n d they differ exactly in the same w a y the sen- tences do T h e seemingly minor c h a n g e from a intransitive verb phrase ("he is h a p p y " ) to a transitive verb phrase referring to an element of the antecedent ("he respects her") turns an exi- .stential quantification ("any m a n is h a p p y if there
ls a w o m a n he loves") into a universal quantifica- tion ("any m a n respects a n y w o m a n he h a p p e n s to love") A n d this is the quantification which virtu- ally "falls out" of the Horn-clause representation
of theses sentences
It will be obvious that other restrictive constructions have to be treated the same way
W h e t h e r w e say "a m a n loving a w o m a n repects her" or "a w o m a n loved b y a m a n adores him" or
"a m a n respects a w o m a n provided he loves her" -
in each case w e will have to represent these restrictive expressions as right h a n d terms, as additional conditions on the values of the corres-
p o n d i n g variables W e could therefore sketch the following informal translation correspondences:
11
Trang 5• ~! ) ,
n o u n or adjective, if the v e r b Is to be"
i.e the grammatical predicate of the sen-
tence b e c o m e s the logical predicate consti-
tuting the clause head;
2 an indefinite N P becomes a predicate on
the right h a n d side of the the clause;
3 pronominal reference is represented b y the
use of the same variable n a m e within one
clause :
4 restrictive phrases ( restrictive relative
clauses, restrictive adiectlves, conditional
clauses) b e c o m e additional terms on the
right h a n d side of the clause
Using these straightforward translation rules, w e
get a representation of surface sentences w h e r e
the correct quantification, in m a n y cases, "falls
out" of the Horn-clause representation In these
cases w e can then say that an indefinite n o u n
phrase corresponds neither to a universal nor to
a n existential quantifier but that its quantification
is a function of its position in the sentence W e
will soon see that t h i s kind of nice one-to-one
m a p p i n g is possible only in a few, simple, cases 4
If w e try to s u m u p w h a t w e gleaned from
examples Ii a n d 12 w e could sketch a rule i%3:
1%3) In a restrictive n o u n phrase those of
its a r g u m e n t s are universally quanti-
fied that are referred to b y the main verb;
otherwise they are existenti-l]y quantified
If w e combine restrictive constructions with "exi-
stentially quantiflying" v e r b forms, as in example
21
21) A text editor which m a d e modifications
to a text file erased it,
w e notice that the quantification imposed b y the
main verb overrides the quantification s u g g e s t e d
b y the restricitve construction E x a m p l e 21 w o u l d
h a v e to be represented s o m e h o w along the lines of
21a: s
21a) text_editor (editorl)
text_file(filel)
modifies(editorl, fflel, timel)
erases ( editorl, filel, timel)
before(timel, now)
4 W e do not propose that all natural language
sentences can be represented as (the
Horn-clause version of) First O r d e r Predicate
Calculus sentences B u t it seems a sensible idea
to start our search for sources of implicit q u a n -
tificational information with those simple cases
w h e r e it is possible
s Existentially quantified variables not in the
scope of a universal quantifier are represented
in Horn-clause logic as a system-generated con-
stant, a so- called Skolem-constant, such as
"filet"
W e thus h a v e to modify i%1 to the effect that the main v e r b form enforces its quantification for all
d e p e n d e n t values
2.1.3 Non-restrictive Constructions Nearly all restrictive constructions of the type mentioned in the last section h a v e their non-re- strictive counterparts T h e restrictive relative clause in example 22 has its counterpart in example 23, w h e r e an additional pair of c o m m a s is the only syntactic difference, although the m e a n - ing of the two relative clauses differs f u n d a m e n - tally
22) S w a p space which is u s e d for storing editor
p r o g r a m s is kept small
23) S w a p space: which is u s e d for storing editor programs, is kept small
In 22, the restrictive relative clause adds, of course, one m o p e restriction In 23, the non-re- strictive relative clause asserts additional informa- tion T h e author wants to m a k e sure that the reader is a w a r e of these facts, a n d that he absorbs the information if it's n e w to him before
he goes on reading Accordingly w e w o u l d h a v e
to represent these examples as 22a a n d 23a
22a) kept_small(S) :- swap_space(S),
used_for_storing_editers (S)
23a) kept_small(S) • - swap_space(S) used_for_storing_editors (S) : - swap_space(S)
W e u s e d the v e r b in the present tense to k e e p the situation as simple as possible If w e n o w consider the other possible case, with the v e r b in the past tense or in one of the m a r k e d aspects,
w e will note that 24 is o d d to the point of being ungranunatical, while 25 is perfectly normal
24) A text editor, u s e d for m a k i n g modifications to
a text file, brought the s y s t e m to a standstill 25) A text editor u s e d for m a k i n g modifications to
a text file brought the s y s t e m to a standstill
W e can consequently outline rule i%4
1%4) Non-restrictive constructions translate into additional, universally quantified, assertions
Apart from the relative clauses a n d the redu- ced relative clauses in the preceding examples w e can find non-restrictive constructions in the fol- lowing cases :
I Present participle : 26) A text editor corrupting text fries is utterly useless
2V) A text editor, m a k i n g it easy to modify text files, is eminently useful
2 Appositive constructions:
28) A m e s s a g e that deleted files will be ex-
u n g e d b y the s y s t e m will be displayed
v e minutes before expunging takes place
Trang 63
29) Another kind of m : % ~ that the
displayed a b o u t one millisecond
before i t actually happens
30) My friend Peter was here last night
31) My friend, Peter, was here last night
32) A command to d e l e t e a file will be
executed with p r i o r i t y
33) Another type of command, to save a file,
will be postponed f o r a few minutes
34) T h e decision w h e t h e r to s a v e o r d e l e t e
a file is n o r m a l l y made b y the u s e r
35) Another decision, whether to crash or
not to crash, normally i s n ' t
Prepositional p h r a s e s :
36) A b a c k u p file on d i s k is immune from
the e f f e c t s of s y s t e m c r a s h e s
37) A backup file, on disk, is immune
from the e f f e c t s of s y s t e m c r a s h e s
In this case the non-restrlctlve variant,
37, has a strong connotation of causality:
" A s the file is n o w on disk, it is i m m u n e
from the effects of crashes"
In all these cases the non-restrlctive
construction asserted additional universally
quantified information, although the appo-
sitive constructions seem to cause more
problems than the other cases
39a) p r i n t s ( P , C)
b o l d _ f a c e d ( C )
: - c e n t r o n i c s _ p r i n t e r ( P ) , character(C),
e s c a p e _ s e q u e n c e ( E ) ,
r e c e i v e s ( P , E )
: - e a n t r o n i c s _ p r i n t e r ( P ) ,
c h a r a c t e r ( C ) ,
e s c a p e _ s e q u e n c e ( E ) ,
r e c e i v e s ( P, E )
In s p o k e n language w e could distinguish bet-
w e e n the two readings of sentence 38 b y m e a n s of stress: T h e second reading (38b) could be enfor- ced b y stress on the verb ("A Centronics printer will P R I N T a bold_faced character") while an e v e n stress distribution on the whole verb phrase (", will P R I N T A B O L D _ F A C E D C H A R A C T E R " )
w o u l d m a k e the first reading (38a) far more pro- bable In written language w e could resort to topicalizers such as "even'r: "A Centronics printer will e v e n print a bold-faced character ." It is interesting to note that even in examples 39 a n d
40 which are quantiflcatlonally u n a m b i g u o u s for syntactic reasons alone (39a) the stress is evenly distributed on the verb "print" a n d the adjective
"bold-faced" (or on the adverbial "in boldface", respectively) As a matter of fact we could say that stress in English virtually m a r k s certain
w o r d s of a sentence as "to be represented as clause heads" in the Horn-clause translation of the sentence, with the consecmences for their quantification w e just outlined, v
2 1 4 Adjectives as Object Complememts
If the verb of a sentence is a causative verb w e
can express the quantification of its a r g u m e n t
values b y the choice of the appropriate object
complement Example 38 is a m b i g u o u s as far as
the quantification of "a bold-faced character" is
concerned (the two readings are "will print s o m e
bold-faced character", 38a, a n d "will print a n y
bold-faced character" it gets, 38b), w h e r e a s in 39
a n d 40 the same expression is u n a m b i g u o u s l y
quantified; both 39 a n d 40 are m a p p e d into 39a,
m e a n i n g "will print in boldface a n y character" it
gets s
38) A Centronics p r i n t e r will print a b o l d - f a c e d cha-
r a c t e r whenever it r e c e i v e s an escape s e q u e n c e
39) A Centronics p r i n t e r will print a c h a r a c t e r
b o l d - f a c e d w h e n e v e r it r e c e i v e s an escape
sequence
40) A Centronics printer will print a character
in boldface w h e n e v e r it receives an escape
sequence
38a) prints(P,skl(P,E)) :- oentrenics_printer(P),
escape_sequence(E), receives(P, E)
bold_faced(sk1(P,E)) : - centronics_printer(P),
e s c a p e _ s e q u e n c e ( E ) ,
r e c e i v e s ( P , E)
c h a r a c t e r ( s k i ( P , E)) : - centronics_printer ( P ),
escape_sequence (E), receives(P, E)
38b) p r i n t s ( P , C ) : - c e n t r o n i c s _ p r i n t e r ( P ) ,
e s c a p e _ s e q u e n c e ( E ) ,
r e c e i v e s ( P , E )
2.1.5 Conjunctions
In the examples 38 to 40 w e used the conjunction
" w h e n e v e r " instead of the neutral "if" This isn't quite unproblematical, as the choice of a conjunc- tlon m a y well have its o w n influence on the q u a n - tlflcatlon of some of the values in the sentence(s) involved H o w e v e r , the precise character of this influence is unclear to us at the present time In example 41 the n o u n phrase "a student" s o m e h o w seems to have a "higher content" of universal quantification than 42
41) If a student k n o w s the w o r d s of a text he
can translate it
42) W h e n a student k n o w s the words of a text he
can translate it
B u t the two subtly different interpretations seem
to be possible only because both "he k n o w s " a n d
he can are ambiguous: In 41 they can be read
as "he already k n o w s " a n d "he is capable of,
k n o w s h o w to", whereas in 42 they can be read
as has looked u p / h a s found out a n d he m a y
s Existentially quantified variables in the scope of
a universal quantifier are represented as system-generated functions, so-called Skolem- functions, w h o s e a r g u m e n t s are the variables over which these universal quantiflers range
v P h e n o m e n a such as the topic/focus-distinction
a n d stress/intonation are often considered as purely styllstic in character T h e examples used will s h o w that this view is often unjustified
T h e P r a g u e school has, of course, always emphaziaed that these linguistic m e a n s are often
m u c h more than "style" See the most recent contribution b y the P r a g u e school, Sgall 1984
13
Trang 72.2 S E M A N T I C M E A N S T O E X P R E S S
Q U A N T I F I C A T I O N
2.2.1 Meaning and T y p e of the V e r b
Although the syntactic m e a n s to express quantifi-
cation can explain quite a few cases of "implicit"
quantification there are cases w h e r e they are not
sufficient T w o such cases are examples 43 a n d
44
43) A m a n who loves a w o m a n will defend her
a g a i n s t an a t t a c k e r
44) A millionaire who is concerned a b o u t his a f t e r -
life will donate p a r t of his money to a c h a r i t y
It is intuitively quite certain that w e have to
represent these sentences in a fundamentally dif-
ferent way, namely as 43a a n d 44a
43a) defends_against(M,W,A) : - m a n ( M ) , w o m a n ( W ) ,
loves(M, W), attacker (A, W )
44a) donates_to(M, s k l ( M ) , s k 2 ( M ) ) :-
millionaire(M),
concerned_about_one' s _ a f t e r l i f e (M)
p a r t _ o f _ m o n e y ( s k l ( M ) ) : -
millionaire(M),
c o n c e r n e d _ a b o u t _ o n e ' s _ a f t e r l l f e ( M )
c h a r i t y (sk2 (M) : -
miUionaire(M),
concerned_about_one's_afterlife (M)
T h e very meaning of "to defend" seems to enforce
an universal quantification for both of t h e t w o
object values, w h e r e a s the m e a n i n g of "to donate"
seems to create an existential quantification for
its two object values W e could, as a matter of
fact, paraphrase 44 as "If y o u w a n t to find a
charity, or if y o u w a n t to see some money, all
y o u have to do is to find a millionaire with p a n g s
of religion, a n d eventually y o u will see him give
m o n e y to a charity" T h e m e a n i n g of "to donate"
implies that the person donating something
already has, or can easily get, w h a t e v e r he dona-
tes; he does not have to wait for it to come his
way Equally, the m e a n i n g of the verb implies
that it will be a trivial task to find a taker for
the donation T h e m e a n i n g of "to defend", on the
other hand, implies that the integrity of someone
or something is defended against a n y conceivable
threat, but only if a n d w h e n a threat b e c o m e s
visible T h e same thing applies to the person etc
defended, hence both object values are univer-
sally quantified (provided, of course, the form of
the main verb permits it)
2.2.2 T y p e of D i r e c t O b j e c t
T h e r e are relatively few cases w h e r e the m e a n i n g
of a verb will u n a m b i g u o u s l y determine the quan-
tifiaction of its a r g u m e n t values O n e verb w h e r e
this is certainly not the case is "to give" It has
( a m o n g others) the m e a n i n g of "to pass on some-
thing if a n d w h e n one gets it" a n d "to h a n d over
something one already has" (in this sense it is
almost equivalent to "to donate") It's these two
readings which are u n a m b i g u o u s l y chosen in
examples 45 a n d 46, respectively, as is m a d e
clear in their clausal representations 45a a n d 46a
45) Decent people will g i v e lost and found property to the police
46) Decent people will g i v e p r e s e n t s to t h e i r p o o r
r e l a t i v e s
45a) g i v e ( D , P , p o U c e ) : - people(D), decent(D),
l o s t _ p r o p e r t y ( P ) ,
f o u n d ( P )
46a) g i v e ( D , s k l ( D , R ) , R ) : - people(D), decent(D),
relatives ( R, D), poor(R)
presents(skl(D,R)) :- people(D), decent(D),
relatives(R, D), poor(R)
Again, w e can say that the v e r y m e a n i n g of the
n o u n phrase "lost a n d found property" excludes
an existential quantification Y o u simply cannot find something intentionally O n the other hand,
a present is, b y definition, something y o u m a k e
or buy, i.e y o u virtually bring it into local (to the recipient) existence, unless, of course, y o u pass on a present y o u got, w h i c h is considered in poor taste in our societies This l a s t point brings us to yet another source of implicit q u a n - tificatlonal information: Pragmatic information, including world knowledge, situation a n d dis- course context
2.3 P R A G M A T I C M E A N S T O E X P R E S S
Q U A N T I F I C A T I O N Here w e will look at the last remaining example of the original collection, viz
13) A m a n w h o loves a w o m a n will give her a ring
Here, the m e a n i n g of the direct object "a ring" is not sufficient to determine its quantification A ring could be found a n d passed on to s o m e o n e one loves, as well as b e e n b o u g h t a n d given away H o w e v e r , our world k n o w l e d g e (rather than our language knowledge) tells us that a m a n doesn't normally h a v e to wait until he finds a ring if he really w a n t s to give one to a cherished person H e can go a n d b u y one; there are rings affordable to just about anyone That's w h y 13a
w o u l d be heavily favoured over 13b
13a) gives(M, s k l ( M , W ) , W ) :- man(M), w o m a n ( W ) ,
loves(M, W)
ring(skl(M,W)) man(M), w o m a n ( W ) ,
loves(M, W)
13b) g i v e s ( M , R , W ) :- man(M), w o m a n ( W ) ,
loves(M, W), ring(R)
Similarly, discourse a n d situation context can determine the quantification in otherwise ambigu- ous sentences, such as 47
47) This printer will print a bold-faced
character if y o u hit this k e y here
Here the situation context, as referred to b y the three demonstratives, seems to impose an existen-
tlal quantification on a character T h e sentence clearly m e a n s that pressing the k e y referred to will immediately result in the creation of a character, which will also be in boldface
Trang 83 CONCLUSION There are quite a few sources of "implicit" quan- tification in English, most of them syntactic, some semantic, and a few pragmatic in character Some
of them fall into the category of linguistic means often considered purely stylistic, such as the toplc/comment-distlnctlon and stress/intonation
A C K N O W L E D G E M E N T
This work was supported under Grant Nr
81 703.0.79 of the Swiss National Science Founda- tion
4 B I B L I O G R A P H Y
Barwlse,J./Cooper,R., 1981, Generslised Quanti-
fiefs and Natural Language, in: Lingu-
istics and Philosophy, 4 (1981): 159-219
Frey, W./Reyle, U., 1983, Lexical Functional
G r a m m a r und Diskursrepr~sentationstheorl e
als Grund/age eines sprachverstahenden
Systems,
in: L i n ~ s t i s c h e Berichte 88/83: 79-100
Oroenendljk, J., et al., 1981, ed., Formal Methods
in the Study of Natural Language, I,
Amsterdam
Kamp, H., 1981, A Theory of Truth and Semantic l~.epresentation,
in: Groenend/|k 1981: 277-322
Karttunen, L., 1976, Discourse l%eferents,
in: McCawley 1976: 363-385
McCawley, J.D., ed., 1976, Notes from the Lingu- istic Underground, Syntax and Semantics, 7,
N e w York: Academ/c Press
McCawley, J.D., 1981, Everything that Linguists
have always Wanted to K n o w about Logic,
Oxford: Blackwell
Platteau, T., 1980, Definite and Indefinite Gene-
rics, in: van der A u w e r a 1980: 112-123
l%ussell, B., O n denoting,
in: Mind, NS, 14 (1905): 479-493
Sgall,P., ed., 1984, Contributions to Functional
Syntax, Semantics, and Language
Comprehension, Amsterdam: Benjamins
Strawson, P.F., O n l~eferring,
in: Mind, NS, 59 (1950): 320-344
9an d e r Auwera, J , 1980, e d , The Semantics of Determiners, London: Croons Helm
15