PERSPECTIVE PAPER: LINGUISTICS
Petr Sgall
Charles University
Introduction
The book by Sparck Jones and Kay (1973), which analyzes the importance of linguistics forvarious domains of information science on the basis of an exhaustive examination of thetrends and achievements of information retrieval, as well as the two subsequent surveys of
the work in the field by Walker (1973) and Damerau (1976) make it possible to reconsider
the role of linguistics in connection with the use of computers, taking into account thedevelopment of research in the last two decades, and the conditions of this development, as
determined by internal and external factors. We would like to divide our remarks into four
sections: (1) preliminary remarks on the relationships between linguistics and document
retrieval, fact retrieval, and communication of man with a robot; (2) questions of linguistic
theory and its new developments, as relevant for information science; (3) linguistic aspectsof fact retrieval; (4) connections between linguistics and programming or computer sciencein a narrow sense.
Linguistics and Information Science
Document retrieval, which was the main object of the book by Sparck Jones and Kay,requires a detailed linguistic elaboration of many domains. Among them are the lexicon
and its structure (word formation, semantic relationships between lexical units);
morphemics (the word as a set of wore forms); word classes; classes of phrases (especially,
the structure of the noun phrase as the typical shape of a term consisting in more than one
word, from tooth-brush and consonant cluster through man-of-war and man in the street
to bookkeeping by double entry, etc.); types of contexts (for statistical and other studies ofcooccurrence of words); and, of course, many other questions. But still, Sparck Jones and
Kay are undoubtedly correct when they write (pp. 61, 105, 111, 151, 158) that document
retrieval has been connected, first of all, with "the use in a more or less ad hoc manner of
linguistic information", with "quasilinguistic techniques" (for instance, the occurrence of
prepositions is often used to identify noun phrases which might be relevant). On the other
hand, the application of full-fledged linguistic models (transformational grammar,
predictive analysis) can be found in connection with fact retrieval, and is only exceptionalin document retrieval systems. (Let us note that, for inflectional, and perhaps also
agglutinating, languages, an analysis of the endings of successive words may be perhaps
even more useful than the analysis of prepositions is for English texts; see Kirschner and
Buranova (in press).
Only a relatively small part (Chapter 7) of the book by Sparck Jones and Kay was devoted
to fact retrieval, but the authors stated that "work in this area shows more of the shape of101

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things to come than anything else. . ."(p. 174). Walker and Damerau have confirmed thisview explicitly, and their comprehensive surveys of the development of information
retrieval since 1971 show convincingly that the expansion resulting from experimenting
with fact retrieval (question answering) systems is most important for the future of thedomain.
Thus, there* are good reasons for a reexamination of the utility of linguistics for
information science to be focused on fact retrieval rather than on automatic indexing andother methods of document retrieval. First, it is in the former domain that linguistic
methods and linguistic systems may contribute to the basis of the study. With document
retrieval it would suffice, probably, to use linguistic techniques based on a traditional
approach, the discussions concerning methodological questions and linguistic theories in thestrict sense being rather irrelevant here for the time being. And second, the developmentof research in information retrieval has been determined, since the beginning of the 1970's,
by question answering systems rather than by investigations in document retrieval.
Therefore, we want to devote our contribution to the relationship between linguistics andfact retrieval. In the next section some issues of the theory of language will be examinedfrom the viewpoint of the question - - formulated: by Sparck Jones and Kay - - whether asubstantial improvement of linguistic theories, "which are still far from adequate" (p. 198;
cf. also pp. 80, 187), will contribute effectively to the "interpenetration" of linguistics andinformation science as two "natural bedfellows". Before starting that section, it might beuseful to characterize briefly some more recent aspects of this question of the utility of
linguistics for information science and artificial intelligence, especially from the viewpointof what new insights and requirements Winograd's (1972) S H R D L U has brought into thediscussion.
It is certainly possible to argue against the specific methods of grammatical and semantic
description chosen by Winograd, claiming, e.g., that he has no large knowledge of linguistic
writings, that he simplifies matters so that it will be necessary to redefine many of his
linguistic notions if his system is to work with thousands of words instead of two hundred,or if his robot is to manipulate more differentiated objerts, etc. Also, it is possible tomaintain that his approach to questions of language has not directly brought a newparadigm of linguistic theory.
But still, his personal knowledge of specific linguistic
questions (in the "traditional" sense of the term linguistics, which in his terms includes
transformational grammar, too) might not be decisive in this respect. (Let us remember
that, in his time, Franz Bopp was said to have too weak a knowledge of Latin to beconsidered a good linguist, but it was he who introduced a programme of Indo-European
comparative linguistics, which was carried out in the development of linguistics through thenext hundred years).
The main new factors Winograd's approach has introduced into linguistics consist neither
in his choice of linguistic theory, nor in his opinions on this or that type of phrase. They
concern primarily the relationship between a description of linguistic competence and otherfields, particularly, a theory of performance, pragmatics, a theory of reference.
To
illustrate this point, let us first examine briefly some linguistic aspects of Winograd's study.
It appears at first that Winograd has turned upside down many of the values consideredbasic in algebraic as well as in structural linguistics. While analyzing the text, he does notproceed from one level of its representation to another, he does not work with the term
sentence (not using any unit between clause and text), and he applies a grammar that was
not equipped with an explicit framework before, i.e., Halliday's systemic grammar.
Winograd states that the generative power of his recognition routine exceeds that of102

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context-free grammars (p. 82) and can be compared w i t h that of unrestricted rewriting
systems (cf. pp. 43ff regarding Wood's transition networks, which could be translated
almost directly into P L A N N E R programs). He points out that man, in distinction to
deductive systems based on predicate logic, has "a large set of heuristics and procedures f o rsolving problems at different levels of generality" (p. 39) and uses them also as a hearer inthe process of communication, when he resolves the ambiguity of words and phrases,
applying not only his linguistic competence, but also his knowledge about the world to
exclude unacceptable parsing variants (p. 33 and passim).
After a more detailed examination of Winograd's approach, one may infer that thedistinctions between his standpoints and those having been more or less common in
algebraic linguistics, as far as the points mentioned are concerned, need not be regarded as
crucial. The division o f linguistic description into levels is present in Winograd's study aswell as with Chomsky or, e.g., in the writings of the classical Prague school of structural
linguistics. Each of the levels is described by a specific device in his system: The so-calledmorphographemic representation is achieved (or, morphemic analysis is performed) by his
input program, combined with the dictionary l o o k - u p (pp. 5, 73ff, 9 3 f f ) . Syntax is, ofcourse, held apart f r o m semantics, and the level of linguistic semantics is treated by acomponent of his system other than the (deductive) analysis of the robot's knowledge of
the world (the former being handled by the component called Semantics, pp. 126ff*. thelatter by Blocks, pp. 117ff). Certainly, the interaction between these components is typicalf o r Winograd's system; at many points of the parsing, Semantics can be called to check
whether this or that parsing variant is to be pursued, and Semantics may call Blocks to see
whether this or that noun-phrase, for instance, would be nonsensical.
Thus it ismeaningful to argue whether a NP the street in a car (in / rode down...) should be
excluded by the semantic or rather by the cognitive component. (Winograd speaks here, p.
23, about the semantic analyzer, without discussing the borderline between linguisticcompetence and knowledge of the world f r o m this viewpoint.) In any case, the interaction
between components is possible only i f these components d i f f e r f r o m each other (we w i l lreturn to t i i s point below).
Winograd's attitude to the term sentence is not so deeply distinct f r o m classical linguistic
viewpoints as it might seem. He just speaks (pp. 17ff) about a major clause ("which could
stand alone as a sentence"), more or less avoiding the traditional term so as to be able totreat coordinated major clauses in a way similar to sequences of utterances in a text. But
this last point - - the absence of a strict distinction between sentence boundary andcoordination - - has been well known f o r decades in linguistics (cf. Danes, 1951; Pitha,
1967; A l l e r t o n , 1969; Katz and Fodor's, 1963, maxim concerning the synonymy o fcoordinate conjunction with sentence boundary is discussed in Sgall, 1973).
In discussing the f o r m of Winograd's grammar and the remaining features of his approachmentioned above (generative power, use of heuristic procedures, and of the knowledge o f
the world during the process of understanding a text), we must bear in m i n d that his aim is
not to describe a language system, or linguistic competence, but to describe linguistic
performance (or the functioning of language in the process of communication), to present
a model of language use, as he himself puts it (p. 3). Thus, if he has been successful inshowing that, for his aim. this or that (or none) of the approaches known f r o m algebraic
linguistics is as suitable as his own theoretical basis, this does not prove anything about the*Wc assume that, e.g., the terms "semantic subject" and "semantic (first, second) object" (p. 132) belong to thelevel of output representations of this component.

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appropriateness of linguistic theories as such.
It is another goal to describe theunderstanding of language — where shortcuts using extralinguistic knowledge are necessary
for disambiguation and also perhaps involve the necessity of a greater generative power - than to describe language as such, with every detail of its intricate structure (but excluding
non-linguistic items). One can discuss whether this or that goal is more appropriate, but,
first of all, it is necessary to distinguish between the two of them, which might be mademore difficult with such formulations as the following: "Language is a process ofcommunication between people, and is inextricably enmeshed in the knowledge that thosepeople have about the world"(p. 26). This process, that of communication or of linguistic
performance, is distinct from language itself; this process is identical not with language, butwith its use or functioning. Different languages can be used in such a process, even ifexactly the same knowledge about the world is involved. A theoretical description of
language itself definitely cannot be identical with a description of the process ofcommunication. Some applications of linguistics require a model of language use, but they
are still limited to experiments with a very restricted universe and also with a very
restricted portion of natural language. If, in Winograd's experiment, only 200 lexical units,
only a dozen extra-linguistic objects, and only one pair of interlocutors are involved, then,certainly, it would be out of place to use a very complicated grammar of English, with adetailed description of English syntax. But if linguistically oriented systems of artificial
intelligence are to be applied practically to a wider domain of tasks, will it not be useful tostate explicitly that the system of language (langue, linguistic competence) is complicatedenough to deserve to be described in itself? Such a description appears necessary, if theinteraction with other subsystems of human knowledge should be handled (e.g., at therelevant points of a syntactic description, cognitive procedures are then called to intervene).
If I am not mistaken, Winograd's system acts in this way, in principle, and it remains only
to state it (and to check whether his type of grammar is capable of being complemented as
to account for most different phenomena of the syntax of natural language).
One more argument might be useful to make the idea of a relatively independent
description of language more plausible. It is needed not only by pure theory, but also bydifferent types of applications, where we are not concerned with a given and restrictedsubset of the universe, but where it is necessary to be prepared to handle most divergent
sets of non-linguistic objects. Leaving out language learning (which could appear as too
remote from the domain of artificial intelligence, although in the epoch of programmed
learning this remoteness might not be quite certain), let us recall machine translation.
Although Winograd refers to machine translation only as "having failed" (p. 42), he
remarks about some of the systems built with the aim of an automatic syntactic analysis(which could be used for MT as well as for information retrieval or in the framework of
man-machine communication in artificial intelligence), namely, those of Petrick and,especially, of Woods. He does not mention the approaches of Kay, of Mel'cuk, of theFrench group (Vauquois), of Kittredge (TAUM). I do not want to discuss the perspectives
and possibilities of these groups now. I would like only to mention that the "failure" as yet
to find procedures to handle the whole domain of grammar of natural language may wellbe due to the impossibility of concentrating the work of the rather small individual
groups* and of equipping them with a thorough knowledge of different linguistic theories.
But it is necessary, in the given context, to point out that the parsers designed fortranslation•Walker's remarks concerning the possible effect of a concentration of the resources expended on question
answering systems (p. 81) also may be well applied to the scattered research on machine translation. As
Damerau notes (pp. 27-29), several groups continue to develop operationally-oriented (even if not purelycommercial) systems of translation, others being interested in systems of translation that could be used inside
other systems (e.g.. as a vehicle for their evaluation)

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cannot use much factual information, so that they have to rely on linguistic analysis properto an extent greater than Winogracl's approach has. More precisely, they also have to v/ork
with "general knowledge" (and preference or priority for this or that parsing variant), as
well as with the knowledge of a given branch, and they should be able to use factual
information gained in translating the previous portion of a text (not only the informationfrom the local, but also that from the overall discourse context). For this, Winograd's wayof handling the interaction of the components of his system might be of highest
importance for the formulation of recognition routines. But still, MT systems must be soformulated as to provide for an interaction of the linguistic system proper (and that ofgeneral knowledge) with several (interchangeable) stocks of non-linguistic knowledge - and also for an interaction of these stocks of knowledge with several (interchangeable)
descriptions of natural languages. Thus, a relative independence of linguistic descriptions
should be acknowledged.
Even if we could proceed to discuss various minor inadequacies and misformulations ofWinograd's, it will be more useful to state that, although his combination of a linguistic
description with that of a part of the world (in the form he declares) does not constitute amajor contribution to the development of linguistics, there are at least two aspects in whichhe (as well as other authors who have achieved positive results in man-machinecommunication, cf. the writings of Hays, Kay, Klein, Schank, Wilks and others) reallycontributes to a new understanding of the structure of language and of the tasks oflinguistics:(a) The use of linguistic descriptions in artificial intelligence provides, as Winograd
puts it, "a rigorous test for linguistic theories" (p. 2).
Although this, of course, is not a direct operational testing of (explicit and complete)theories, and although such testing has not yet proceeded far enough to permit it to beevaluated properly, it might be useful to add here several remarks concerning this point.
In accordance with what has been presumed already by many linguists, Winograd's
approach (see especially p. 16) corroborates the view that such applications as those in thedomain of artificial intelligence (as well as MT) are better served by those types of
linguistic description that connect meaning and sounds explicitly. The fact that Winograd
has not chosen any of the more or less formally elaborated systems of stratificational orfunctional description migh: have been caused by biographical factors. In any case, theunderlying linguistic approach he has chosen, Halliday's systemic grammar, has much incommon with the types of description elaborated by Mel'cuk, Lamb, Vauquois, Hays, by
our Prague group, etc., especially in what concerns the relationship between semantics andsyntax.* There are several levels, each of them having its proper syntax, and they aretreated as ordered between the level of sound and thai of meaning, each of these twobordering on non-linguistic domains.
Inside transformational grammar, this would
correspond more to the approach of generative semantics. Like most of the authors quoted
above, and like Lakoff, McCawley, and Postal, Winograd also rejects the necessity of a
specific level of deep syntax, formulating his programs as operations connecting each pairof the adjacent levels in the sequence of graphemics, morphemics, syntax, and semantics (asfor the relationship of the last level to the non-linguistic domain, see below).

•Also othei aspects arc in common (which is not surprising, since Halliday as well as most of the other quoted
authors use the classical European structural linguistics as their point of departure), e.g., the use of complex
symbols comprising one lexical unit and the indices or grammatemes accompanying it, instead of handling
grammatical units as if they were independent lexical items.

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Another point relevant in this respect corroborates some views that are opposite to
Chomskyan transformational grammar. The parsers of Winograd, Woods, and others do
not use ordered rules (such as the ordered transformations in some versions of T G ) , butrather proceed f r o m text to grammar. That is, while passing through the representation o f
a sentence, they try to f i n d a solution f o r the given word or word group, instead o fchecking a list of rules and passing through the sentence representation with each r u l iseparately, to see whether, at the given point of the analysis, it can be applied. W i t h
Winograd, this attitude is pronounced to such a degree that he does not proceed f r o m therepresentation o f the sentence (his major clause) on one level to that on another. Rather,he goes up to the highest levels (including that of the non-linguistic knowledge) alreadywith the first NP that is being parsed, to eliminate the "nonsensical" parsing variants assoon as possible, so as not to burden the further portions of parsing by having to considerthem.
It is to be noted that with some systems (such as the functional generativedescription) this text-to-grammar orientation has been present in the generative as well as
in the recognition routines.
(b) The other, and probably most important point in which the impact ofWinograd's approach influences the development of linguistics in a decisive way
may be seen in his "imperative f o r m " of representing knowledge and semantics (seeesp. p. 116).
In his system, every semantic d e f i n i t i o n of a word has the f o r m of a program for checking
whether the mentioned object (class, relation, etc.) is present in the machine's memory.
Also every declarative major clause interpreted by the machine is considered an instruction
to deduce consequences f r o m the given statement that may be useful in the further search
for answers lo the input questions. In his way it is possible to design a system more
effective than one based entirely on deductive logic (the formulae of which give us no"strategy i n f o r m a t i o n " , p. 39) and more similar to natural language ( i n which, as Winogradstates there "is no sharp line dividing atomic concepts f r o m nonatomic ones"; "the meaningof any concept depends on the entire knowledge of the speaker"; etc., pp. 26ff).
Certainly, it has to be shown whether this "imperative" and "program" f o r m of semantic
representations and definitions is not connected to a large extent with the specificproperties of a dialogue between man and robot. Other purposes (e. g., fact retrieval, an
automatical encyclopedia, or a theoretical description of language) might require somemodifications or restrictions of this principle. But, as far as we can judge now, it is asound principle which might be basically useful not only for technical applications, butalso f o r the pure theory of linguistics. Incidentally, it is possible to quote at least threeother sources of a similar principally new approach, using instructions, operations, etc.,
instead of semantic definitions or representations. The first of them is the well known
approach of Lewis, of Montague grammars, etc., which ise an operation ( f u n c t i o n ,mapping) as the correlate of the meaning of word or of a word group (e.g., the intensional
sense of an NP being represented by a function or prescription telling us what conditions
an individual or a class of individuals must meet to belong to the extensional meaning o fthat NP). Another source of such a treatment can be seen in the handling of definitions as
instruction in some approaches to modelling of cognition (as seen in the writings of D. G.
Hays and his collaborators).
The third source of such an "imperative" understanding of statements is that connectedwith considerations of topic and focus (theme and rheme. functional sentence perspective,etc.). Although Halliday (1967) describes the "theme" and "focus" structures of English indetail (also using some of the results of Czech linguists, such as Mathesius, Danes, andFirbas), in the book of Winograd these two aspects of the "imperative approach" are not106Perspective Paper: Linguistics
connected directly. Only in his paragraph on questions (pp. 137-141), does he makes amore or less systematic use of the concept of focus. We shall see later what the importanceof these notions is inside the new understanding of semantics.
New Developments in Linguistic

TheoryOne cause o f the fact that the interpenetration of linguistics and i n f o r m a t i o n science is not
yet as intrinsic or intensive as it could be consists in the long development of linguistics asoriented to "human" (i.e., more or less pedagogical, educational) applications.
For
centuries, linguistics has been applied almost exclusively to such practical purposes as theteaching and learning of foreign languages, or the care and culture o f standard languages.
Linguistic theory has developed under a steady influence of the requirements of theseapplications, which have some important features, in common; these features are determined
first of all by the fact that the user of the results of linguistic research always is human(teacher, pupil, reader). And a human being is, as a native speaker of one of the natural
languages, accustomed to use a language.
This means that the characteristics of language use that are more or less common todifferent languages (and partly do not change even i f a dialect is promoted to standard
language) were by far not studied with such an intensity as were those domains of
linguistics connected with features characteristic for individual languages, or for groups ofthem (grammar, lexicon, phonology). Also the causes of the relative lack of systematicsemantic studies in traditional and structural linguistics can be found partly in the fact thatsemantic phenomena, even i f they are not f u l l y identical in different languages, appear as aconnecting link between different languages rather than as points of difference between
them.
Under the influence of the educational applications, linguistics was understood as studying
first of all the system of language (the rules l i n k i n g the sounds of a language with a poorly
understood repertoire of semantic units), not. its use. The problems of language use with
their semantic, psychological, sociological, and other implications have not been altogether
ignored, and they have been studied quite intensively, in some linguistic schools, under theheadings of stylistics, psycholinguistics, sociolinguistics, etc. But most of these disciplines(or their predecessors) have not been urgently needed for practical applications, and theirobjects have not been so appropriate for structural modelling, so that most theoreticallinguistic analyses concentrated on the structure of language, on grammar.
When Chomsky's first writings made it possible to handle grammar as a formal system, it
was not all of linguistics that gained a level of formalization comparable to that of physics
or chemistry, but only the then supposed core of linguistics. And one of the main findings
achieved between 1965 and 1975, ciue to the experiments in fact retrieval, language
understanding, etc., as well as to theoretical research in semantics, consists in the evidence
that formalization alone does not suffice to allow linguistics to be as useful in technicalapplications (in man-machine communication) as physics or chemistry are for industry.
The requirement emerged for studying the questions of the use of language with the same
intensity as those of grammar.
A pupil, as a user of a natural language, knows how to use the items of another language heis taught or reads about. He knows f r o m his mother tongue what sentences may follow eachother, how to identify the antecedent of an anaphorical pronoun, how to switch between /and you in a dialogue, and, even though he would not be able to use the proper terms, he isable to distinguish rather safely, without explicit training (by mere analogy to some clear

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examples) an actor from a goal, a topic from a focus, etc. In these and many other points
he just handles the items of the foreign language (or of a "higher" form of his mothertongue) in the same way that he has been accustomed to handle their counterparts in his
own language. He must be instructed how to express the subject, the passive, what is theshape of the intonation centre, etc., in the language described (of course in many cases hecan do without explicit instruction). But the functioning of such items, many of their
possible combinations in a sentence or in longer contexts, etc., are already familiar to him.
When he achieves the linguistic competence of his "new" language, he can perform (somesecondary points aside), using the ability he had gained for another language (if the cultural
backgrounds of the two languages do not differ too much).
For a machine it is not enough to be instructed in linguistic competence. Many aspects that
had been neglected in linguistics (especially in the U.S.) before the 1960's are now beginningto be studied systematically, cind the influence of technical applications is very intensive forsome of them. The study of the structure of text, rapidly developing first of all in Westernand Eastern Germany, is connected not only with the requirements of the theory ofliterature, but also with those of information retrieval. A sound basis for the classificationof texts, a description of the coherence of texts including such areas as anaphorical relations,etc., are equally necessary for both of them. This applies also to the analysis of dialogue, ofquestions and answers, of the semantic patterns of personal pronouns. Other aspects ofpragmatics, especially those connected with reference, are important for the automatic
treatment of language in artificial intelligence and fact retrieval as well as in modern
psychological research concerning the structure of human memory, knowledge andinteraction with the world. Linguistic competence in Chomsky's sense constitutes only asmall portion of the mechanism of communication, and if we want - - as Martin Kay
formulated the task at the conference on computational linguistics in Varna, May 1975 -- tounderstand how it is possible that a string of symbols has the effect of changing the innerstate of the mind of a human being who perceives the string, then we must regard
computational linguistics not only as one of the applications of theoretical linguistics, butalso as one of its main advanced posts, responsible for the future theoretical development
itself.
We must realize, of course, that up to now not many theoretical linguists have devoted muchattention to computers and information science. Only exceptionally (see, e.g., the writingsof MtTcuk, Lamb, Garvin. Kay, as well as the efforts of the Prague group of algebraic
linguistics) has the work in theoretical linguistics been connected with a more or less directconcern with computing. This lack of understanding of the importance of contemporary"applications" certainly is connected with the fact that questions of performance, pragmatics,
and of the variability of language use (as Walker, p. 88, puts it) have not yet been studied toan extent comparable with that of grammar. But the trend is positive; the younger
generation of linguists (perhaps more in Western Europe than elsewhere, but Lakoff's recent
writings also belong here) is beginning to stress the necessity for studying the main aspectsof linguistic performance. Up to now, perhaps no fully reliable theoretical point of
departure has been found in this domain, but new light has been shed on many empiricalissues in connection with text linguistics and the theory of style. The study of pragmaticalquestions has found a more advantageous position in that some of the issues of pragmatics(especially the status of pragmatical indices or points of reference) have been elucidated
from the point of view of semantics (in the writings of Montague, David Lewis and others;
Schnelle speaks about a "semanticization" of a portion of pragmatics).
The question raised by Sparck Jones and Kay that we referred to earlier, about whether
improvement of linguistic theories will help the interpenetration of linguistics andinformation science, can be answered only by "we still can hope", as far as performance and108Perspective Paper: Linguistics
pragmatics are concerned. But we want to show that as regards semantics, especially thesemantics of the sentence, the answer already may be more positive.
We have already mentioned that the study of linguistic semantics also was largely neglected,
although in this case the relationship between the two main reasons mentioned above may
be other than in the case of performance and pragmatics (the difficult accessibility ofsemantic phenomena being stronger than the fact that their description was not necessary
for traditional applications of linguistics). The study of semantics (not only in the lexicon,
but also in the structure of the sentence) has never been fully absent in some linguistic
approaches. Thus, in the Prague school, semantic issues have been paid attention since itsvery beginnings in the 1920's. Nevertheless, fact retrieval and language understanding havebeen studied without much connection with linguistic semantics, although semantics clearly
belongs to the proper object of these disciplines. The lack of influence of linguistic
semantics on information science has not only external causes. It was not easy to apply the
results of the European schools of linguistics, which have not used an explicit language andhave not been well known in America, where most of the computer models were developed.
But we must admit that the lack of influence was mainly conditioned by the relatively low
level of understanding of the nature of semantic phenomena in linguistics. One of the main
characteristics of the new situation (after the development between 1965 and 1975, which
has been described by Sparck Jones and Kay, Walker, and Damerau) consists in the progress
made in the semantics of natural language.
It is well known that the new attention devoted to semantics in transformational theory led
to the division of this school into the Chomskyan wing and the wing of generative
semantics. Furthermore, the development of these two new theories has confirmed both theclaim that semantics belongs to the core of linguistics (the relationship between sounds andmeanings is the main object of the study of language systems) and the claim that asystematic attempt to include semantics in the transformational description would lead tothe necessity of changing the structure of the description (cf. Sgall, 1964, p. 95). Moreover,
one can see that questions of semantics still belong to the most bothersome issues in bothversions of transformational description. Neither the research based on semantic markers inthe sense of Katz, nor that of lexical decomposition with Lakoff has brought the possibilityof coherent descriptions, the adequacy of which for some not quite restricted class ofphenomena really could be checked. The attempts at a formulation of a variant of predicate
logic which could form the basis for an adequate description of the semantics of natural
language are still far from being successful. It seems that these attempts would have torepeat, in a sense, the development of modal logic, logic of tense, intensional logic, if they
actually were to reach their aim, namely adequacy for the full range of a natural language.
Natural language is a universal system (in which everything can be formulated that man iscapable to formulate, even though not without ambiguity and vagueness), and one of theaims of the development of modern logic and model theory has been precisely to achieve thepossibility of accounting adequately for the semantics of linguistic phenomena.
Certainly, since the period analyzed by Spark Jones and Kay, much has changed with respect
to semantics. While their chapter on semantics is almost entirely devoted to questions oflexicon (so that they could state - - p. 139 and elsewhere -- that semantics was not importantfor information retrieval, at least if questions of term classification are disregarded, see p.
159 and 171), the development of semantics since 1970 concerns first of all the relationships
between semantics and syntax.
If transformational theory, which is, in a sense, acontinuation of the anti-semantic descriptive linguistics (neo-Bloomfieldian structuralism),
although in many respects a polemic continuation, meets serious difficulties v/here
attempting an integration of semantics into linguistic description, then it may be useful tolook for a better understanding of semantics in other trends of linguistics, and in logic.

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First of all, there is the Montague trend, which, as we have already noted, has contributed toa sound treatment of such pragmatical indices (or points of reference) as /, you, here, now.
We can state briefly that the semantics of these four elemerts may be accounted for byvariables which are free in the semantic representation of a sentence (or in the hypersentence inside this representation), while the specific values of these variables —corresponding to their reference -- are determined directly by every occurrence of the given
sentence in*a given text and situation (since the speaker and the addressee, as well as theplace and the time point of the utterance are determined by the utterance token itself, in the
primary form of communication). Other pragmatical indices, such as in my, we, yesterday,
and probably also the country, this building, may be anal>zed semantieally as based on thefour elementary ones. This trend (reDresented, with respect to linguistic semantics, first of
all in the writings of Schnelle and Dahl) also underlies various logically oriented writings(the most detailed analysis of natural language semantics from this point of view has been
given by Cresswell). Howver, we shall see later in this section that the neglect of linguistic
structuring, which has always been connected with the analyses of natural language
semantics by logicians, interferes even here in the underslanding of the relationship between
the semantic analysis based on truth values and the (linguistically important) study of sense.
Those trends in modern linguistics that base their semantic analysis on semantic insights andattitudes of structural linguistics in Europe for the most part have not yet elaborated correct
formal systems. This applies to Lamb's stratificational or cognitive linguistics as well as
Mel'cuk's system meaning < = > text and many other approaches. They often work without
testable criteria and their semantic classification might be suspect in that it is difficult tocheck them for completeness and adequacy, to exclude personal attitudes in completing
them, etc. This observation applies, of course, also to other semantic and cognitive systems,
none of which has been used up to now, as far as I know, by more than a small group of
authors. Nevertheless, although these approaches are not mentioned by Sparck Jones andKay (including Kay's, 1970, own contribution), it follows from their book (pp. 35ff, 71) thattransformational description is connected with various drawbacks which other systems do
not always share. Having worked on questions of the framework of generative description
for almost two decades, I am convinced that at least in two respects it is worth while to look
for a sound basis of semantic analysis in these stratificational or functional approaches:(a) The tradition, based in structural linguistics, of working with diagnostic
contexts in searching for semantic equivalence (synonymy) and semantic difference(ambiguity, homonymy) of surface units has led to elaboration of such criteria as
the dialogue lest (for distinguishing between obligatory "cases" and free adverbials,
see Panevova, 1974, Panevova and Sgall, in prep.), and the question test (for topic
and comment, see Sgall. Hajicova, and Benesova, 1973, Section 3.2, and also thecommentation test of Posner, 1972), and to a better understanding of the test ofnegation (in distinguishing not only meaning proper and pre- supposition, but also
allegation, see Hajicova, 1974; Sgall, Hajicova, and Benesova, 1973, Section 4.2).
These and similar criteria are testable and make it possible to determine the units needed on
different levels of language structure. The search for such criteria will spread necessarily
with the further research in linguistic semantics.
The discussions on semantics intransformational linguistics should be checked from this viewpoint in connection with thedistinction between linguistic meaning and factual knowledge. We would like to add aremark on this distinction here.
Not only must the description of syntax be held apart from describing some domain of
non-linguistic data, as its long history has shown with overwhelming evidence, but also
inside semantics we have to distinguish between linguistic meaning (i.e., the meaning of110Perspective Paper: Linguistics
linguistic units - - elementary and complex - - as well as rules that allow constructing themeaning of a complex whole f r o m that of its constituent parts) and non-linguistic(cognitive, ontological, factual) content. The latter cannot be described by purely linguisticmeans. Only the former can be handled in a general way, for a given language in its
universality, while the latter must be treated in close connection with the specific task, w i t h
the domain of the application. Knowledge of the world must concern either toy blocks on atable, or d r i v i n g a car, etc., but it cannot cover all of them at once in a single model.
Certainly, an area of "general knowledge" can be identified, the content of which may be
useful for many or perhaps all types of use of natural language in man-machinecommunication, but f o r the time being this area, in some sense intermediate between
meaning and content, has not yet been characterized to a sufficient extent.
The issue concerning the distinction between linguistic meaning and cognitive content has
been discussed for decades. From Hjelmslev to D o k u l i l and Coseriu, European structural
linguists have maintained that it is necessary not to deal directly w i t h factual knowledge.
On the other side, most adherents of transformational description maintain that it is thetask of anyone who wants to "insert a level of linguistic meaning" between that of cognitive
content and syntax to bring arguments strong enough to justify the complication of thesystem. But are cognition and meaning really two levels in this sense? Is not meaning justthe single f o r m our "model of the w o r l d " can have? We shall see in the next paragraph that
there are arguments f o r a "European" answer to these questions.
(b) The systems working with a linear ordering of levels ( f r o m semantics to sounds
or graphemes) are more directly connected with (and thus, applicable f o r ) theprocedures o f synthesis and analysis, which are not only immediately needed f o r
the practical purposes of man machine communication, but which also may beunderstood (with some restrictions) as hypothetical f o r rial models of human
linguistic mechanisms.
In some cases it was even possible to show that such a system is connected with a generative
power weak enough to characterize natural language as a specific system (see Platek, 1974,
f o r the Prague functional generative description). It appears most important f o r the statusof linguistic semantics that the sequence of levels f r o m phonetics to semantic representation
be seen as the proper domain of linguistics, while the relationship between semantic
representation and logical languages or cognitive systems is the domain of cooperation of
linguists with logicians, psychologists, and specialists in models of cognitive structures(including semantic networks).
It has been shown that Carnap's distinction between
intension and intensional structure (directly relevant f o r the handling o f non-extensional
contexts, especially of belief sentences), or, in other words, the distinction between t r u t h functional semantics and linguistic meaning (or sense, in logical terms) can be accounted forin a systematic way, f o r a natural language, by a description of the functional type, i f thesemantic representations of sentences are viewed as describing the linguistic meaning (orsense, or intensional structure) of the sentences, while procedures translating these semantic
representations into logical a n d / o r cognitive structures specify the t r u t h - f u n c t i o n a l valuesof the sentences. (See Sgall et al., in prep., for the relationship between linguistic meaning
and Carnap's intensional structure; the translation into a logical language is examined in
Sgall, Hajicova, and Benesova, 1973, Section 7.6; Hajicova, Knzek, and Sgall, 1975, and the
Appendix here).
This treatment of the semantics of the sentence includes, for instance, such distinctions asthat between the two sentences in (1), which appear as fully synonymous (their difference
being described by an optional transformation or in some equivalent way), and those in (2)to (4), which d i f f e r in their linguistic meaning similarly as those in (5) to (7), although theyIIIPetr Sgall
do not differ cognitively. The intensions of the two sentences in (2) to (4) are identical, but
the difference in the intensions of the sentences in (5) to (7) shows that this is not given by
the linguistic structure of those sentences, but only by specific conditions involving, inaddition, the lexical or morphological cast or "setting", i.e., the meaning postulates ofindividual morphemes.
(1)

(a)
(b)

They persuaded
They persuaded

Jim not to return into that company.
Jim that he should not return into that

(2)

(a)
(b)

The old table is yellow,
The yellow table is old.

(3)

(a)
(b)

Tom sold Jack a car.
Jack bought a car from

(4)

(a)
(b)

John talked
John talked

(5)

(a)
(b)

Any old table is yellow,
Any yellow table is old.

(6)

(a)
(b)

Tom sells cars to the citizens of Glasgow,
The citizens of Glasgow buy cars from Tom.

(7)

(a)
(b)

John talked
John talked

company.

Tom.

about Jack to JANE.*
to Jane about JACK.

about many problems to few GIRLS,
to few girls about many PROBLEMS.

Thus it appears, of course, that linguistic semantics proper is connected with a rather narrowconcept of synonymy; many so called paraphrases will turn out not to be fully synonymous,i.e., to take different truth values for different possible worlds or states of affairs. It may
be considered superfluous to work with such detailed classification of the meanings ofsentences, since in many cases they overlap semantically to such an extent that thedistinction between them seems not to be relevant. It can be said, however, that this conceptof strict synonymy is inherent to natural language, so that, if "the way in which semantics
and syntax are combined" (Walker, p. 82) is considered as one of the main points, it is justthis strict synonymy which can be accounted for by linguistic methods. The fact that with a
specific lexical cast such differences in linguistic meaning as that between (2)(a) and (b) are
not relevant, for the cognitive content, can be accounted for by rules translating semantic
representations into cognitive networks (if a single object has two properties, it is noti nportant which of them is structured as the main predicate of the assertion). Similarly, thedifference between (3) and (6) will be treated by describing the converse predicates bymeans of different meaning postulates (or other devices of lexical semantics) which would
coincide in case the transaction concerns two people only and is formulated asaccomplished.
It may be worth while to devote more place to a similar account of the difference
between the pairs (4) and (7), since here the questions of topic, focus, and communicative
dynamism (or functional sentence perspective) are involved. These questions have notyet been studied systematically enough in most linguistic frameworks.
If the relationship between "given" and "new" knowledge is well understood, it becomes
clear that, if the speaker formulates a declarative sentence and communicates it to ahearer as a statement, in the general case, he instructs the hearer to pick up certain"established items" of information (i.e., items that have been already contained in his
memory, primarily in a part of it that has been already activated by the given discourse•Capitals denote the intonation centre here.

112

Perspective Paper: Linguistics
and its situation) and to connect them with items presented as new (or not directly
recoverable), i.e., to modify them somehow, place them in new relationships with otheritems or with each other, etc.*
As linguistic considerations have shown, these two kinds of items involved in a sentence
are divided just in accordance with the dichotomy of what Chomsky now calls
presupposition and focus (only his formulations must be made more precise in somepoints, see Hajicova and Sgall, 1975). Thus, in the situation of Winograd's dialogue withhis robot, if, after point 13, p. 11, the machine is told "I own blocks which are not red",
the words / and own are in the topic here (since the sentence "The blue pyramid is mine"
immediately precedes), they are used as referring to items of information the hearer(machine) shares with the speaker (man) in the activated part of memory. They are used
as recoverable, as "established" items about which something is communicated, i.e., which
are to be modified somehow. This somehow is specified by the rest of the sentence, i.e.,
by its focus: the NP blocks which are not red refes to information not exactly "new"(the machine "knows" that there are such blocks in its "universe"), but not directly
recoverable (in Halliday's terms), or, more exactly, to information which is to be added tothe topic in the hearer's memory. It is defined here what objects "are owned by the
speaker", and it can be checked that this is decisive for the action performed by themachine while "understanding" this sentence. This checking should include the fact thatthe focus includes an "exhaustive list" (see Kuno, 1972) of items standing in the statedrelationship to the topic (exhaustive down to a certain threshold, in the general case).
But this holds only for cases in which the verb belongs to the topic; in the primary casethe verb belongs to the focus (to what is stated about the subject, etc.), so that there is nosuch exhaustiveness. If, e.g., at the given point the machine were told "the red pyramid is
supported by a green block", then the first NP would constitute the topic, the rest being
the focus of this sentence. That is, the machine would be instructed to put theestablished item the red pyramid in the relationship be supported by to the item a green
block (or, more exactly, to check, whether this relationship really is new -- which it isnot, in the given case, or whether it is compatible with the knowledge the machine has,and only if after these steps it proves useful, to add the new information to the given
stock of knowledge).
In the functional generative description of language, this aspect of the declarative
sentence is accounted for by its semantic representation having the form of a dependency
tree exemplified in Figure 1. There the superscript b with the main verb denotes that theverb belongs to the topic, while the expanding elements (participants as well as freeadverbials) stand to the left of their governor if they belong to the topic, and to its right,
if they belong to the focus. With embedded clauses, the concept of topic is thus
relativized in a straightforward way. A procedure for generating such trees has beenformulated, and it has been shown that no excessive generative power is needed. It is notalways easy to find the boundary between topic and focus when parsing a sentence, but
the basis of such an analysis may be formulated according to the transformational rules
for focus, as given in Hajicova and Sgall (1975). Such rules reflect not only thedichotomy, but also the whole hierarchy of communicative dynamism (or "deep word
order").
It is well known today that the topic/focus dichotomy as well as the scale ofcommunicative dynamism are semantically relevant, in the general case; the examples (4)and (7), taken over from Lakoff, illustrate this fact. It is possible, in the context ofWinograd's study, to point out that the sentence (8)(a) should be interpreted in anotherway than (8)(b).
•For a more detailed discussion see Sgall, Hajicova. and Benesova (1973). especially pp. luff., 70-73, 158ff,
251ff.

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Petr Sgall

ifall-Pret-clause
Charles

Neg

wife
ill

he-Possess
Fig.1 — Charles didn't come since his wife fell ill

(8)

(a)
(b)

Now cubes are mostly in the BOX.
Now in the box there are mostly CUBES.

With our approach, these distinctions are accounted for by the scale of communicative
dynamism, i.e., by the order of the elements of the corresponding semantic
representations, which is correlated with the order of quantifiers in a logical formula.
(For the translation procedure yielding the mentioned correlation, see the Appendix andthe references quoted there.)
The dichotomy of topic and focus is also connected with the organization of humanmemory, or of the stock of knowledge (and other kinds of psychological phenomena).
Human memory is a vast domain, structured in various ways, and if an act ofcommunication is to be effective, the understanding of the message should not require
more than a minimal effort on the part of the hearer. Only some elements of his
memory are foregrounded by the situation of the discourse, and the required effort issmaller if some of these elements are chosen as the established items by the speaker andif the lexical units referring to them are marked as such, being (primarily) placed at the
beginning of the message. Point after point, the message can be expanded; or, in otherterms, the communicative act consists in a structure of messages linking with each other.
Thus, in the unmarked case, the established items are referred to prior to thespecification of their desired modification.
If the sentence of a natural language is considered the systemic form of an elementarycommunicative act, its structure may be expected to reflect the basic conditions ofcommunication. This standpoint then allows us to understand why the sentence includes,
besides the syntactic patterning (consisting in the hierarchy of verbs and their114

Perspective Paper: Linguistics
participants, with their inner structure, the f i n i t e verb of the main clause representing thecentral point of this hierarchy), also a communicative patterning, in which the parts
referring to the established items (in the above sense) are distinguished f r o m the parts
concerning the modification the speaker has in mind (the added i n f o r m a t i o n , in the idealcase). Thus, when formulating a sentence, the speaker has to choose the main predicate
and the topic (the established items).
In the elementary case, the two hierarchies coincide (in such sentences as Jack SLEPTand Mary LIVES the coincidence is most complete), and they were also put together inthe Aristotelian formulations of linguistic and logical structures. During the developmentof logic and linguistics they were not only held apart, but the second of them had been
neglected almost completely for long centuries. Only in the last decades has it beenstudied in a more systematic way, and attempts been made to investigate systematicallythe interplay of the two hierarchies in cases that are not so elementary as the above
examples. In these more complicated cases, the established items are not always identicalwith the subject of the sentence (they may include the subject, but also other parts of thesentence, or may even lie outside the subject), the verb need not specify the modification
wanted by the speaker completely (it may even refer to some of the established items, if
states, activities, etc., are referred to as already known, etc.), the verb may have moreparticipants (with a free choice of those that refer to the established items), some of them
may contain other verbs with their participants, etc.
Thus it is advisable to distinguish the part of the sentence referring to the establisheditems also terminologically (as topic, or theme) f r o m the other part (specifying thedesired modification in the above sense, and called comment, rheme, or focus). In otherterms, the topic may be called the contextually bound part of the sentence ( w i t hembedded sentences, of course, we come to a whole hierarchy, so that it may be
advantageous to hold the terms apart f o r the sake of a more detailed classification).
Contextual boundness does not mean co-textual here, since not only are items known
f r o m the previous portion of the given text included, but also those given by the situationof the discourse. Thus, it is necessary to use, in the description of the structure ofsentences, some pragmatic data concerning the stock of knowledge shared by the speaker
and by the hearer(s). The elements of the stock of shared knowledge (more exactly, thestock the speaker himself has and supposes to be shared by the hearer(s), too) should beclassified according to the degree to which they are foregrounded (activated) in thesituation of the given discourse. This means that besides a (generative or other)
description of language itself, a description of the functioning of language incommunication (a description of linguistic performance) must contain also anothermechanism, describing the stock of knowledge. Inside this stock, the elements (or at least
some of them) are partially ordered in such a way that the ordering relation may beinterpreted as a scale of foregrounding.* Some of the elements of the stock of sharedknowledge are, so to say, permanently foregrounded, and thus the speaker can use them ascontextually bound, and also as presupposed, at any stage of a discourse. It seems that,first o f all, the indexical elements / , you, here, now belong there, but also other notions
closely related to them {my mother, my wife, my children, my country, my town; this year,
this month,
today,etc.),
but perhaps not all nouns of unique reference in the*Thc parallel between the whole stock or' shared knowledge, as distinct from its (most) foregrounded
elements, and permanent memory, as distinct from temporary memory, is evident and calls for experimental
checking (cf. also Chafe, 1973, and the literature quoted there.) We may note only quite hriefly that it is thisslock of shared knowledge, winch should probably be used instead of such unclear notions as "universe of
discourse" or "actual world", if semantic research is to be combined with a constructive approach.

115

Petr Sgall
universe of discourse (cf. Kuno, 1973, p. 39). Olher nouns, the reference of which usuallymusl be specified afresh for every discourse (or even for a certain part of the discourse),
can be foregrounded by this very specification (or, if their referents attract the attentionof the participants of the discourse, also by deixis).
This mechanism would account for the possible use of My wife has read, in a German
weekly, that... as a beginning of a discourse even in a situation where the speaker's wife
is not present, and not known to the hearer. As we have said, it would be necessary to
work with a hierarchy of the elements of the stock of knowledge, using at least a partial
ordering, since, of course, my aunt, your mother, my third grandson, the Old Town of ourcapital, last century, Paris, etc., are noun phrases very suitable for the use inside thetopic of a discourse opening (being connected with at most trivial presuppositions), but,under certain circumstances, my teacher's niece, Aconcagua, or the age of Michelangelo
also would do.
The foregrounded elements can be mentioned, in a discourse, in two different ways: (a) as
contextually bound, and (b) in the focus, along with elements that have not yet been
foregrounded. Compare Charles saw HIM with the object foregrounded (and therefore
pronominalizable) but included in the focus (and therefore stressed) against Charles SAW
him, with the object not only foregrounded (known) but also contextually bound(therefore unstressed). Therefore, the topic cannot be identified with the known, given(or foregrounded) elements.
If an element of the stock of shared knowledge occupies a relatively low position in thescale of foregrounding, it can be introduced in a discourse as contextually non-bound,i.e., in the focus of a sentence. Such a mentioning gives the element a higher degree of
foregrounding; in some respects it is possible to conceive the element mentioned last to
be more foregrounded than the elements mentioned before, the foregrounding of which
already shades away step by step (if they do not belong to the permanent part of theforegrounded elements).
The hierarchical organization of the stock of shared knowledge is relevant also for aninvestigation of the structure of text. It may be assumed that any break in the fluent lineof discourse or text is connected with a more or less considerable change in the set of the(most) activated elements of the stock of shared knowledge. The extent of this change
depends on whether we are concerned with a simple pause between two paragraphs (after
which an issue may be re-evoked that was not mentioned immediately before), with adeeper break (e.g., between chapters), or even with a pronounced discontinuity of the text,
evoked by an outside interference into the discourse. In the first two cases, the change
concerned might be characterized as a switch of a common theme or "hypertheme". Thesenotions, which must be understood as relativized or stretched along some scale, could beanalyzed much more explicitly than up to now, if the interplay of topics (themes) ofutterances, as identified, e.g., by the question test, were understood as reflecting thechanges in the degree of activation of the corresponding elements in the stock of sharedknowledge. Typically, an element is activated by its first mentioning in a rhematic
position. By this very fact it becomes available as a possible thematic element in thefollowing part of the text, and, if the speaker switches to another theme afterwards, theactivation of the given element is reduced. After the newly chosen theme has been
"exhausted", or saturated, it is possible to return to the former theme again, but thispossibility is restricted. If it was the theme of the first utterance of paragraph A, it canwell emerge again at the beginning of paragraph B, but if another theme is chosen here,
the degree of activation of the original theme is again reduced, etc.

116Perspective Paper: Linguistics
It seems, from this point of view, as we have already remarked, that often the element
mentioned last (i.e., the focus of the last sentence of the preceding portion of the text)
can be conceived as more foregrounded than the elements mentioned before, theforegrounding of which already shades away. This would point to the possibility that thepart of human memory corresponding to the foreground of the stock of sharedknowledge could be described by a device to some extent similar to a pushdown
automaton (but, certainly, restricted to a finite storage). Some examples corroborate theview that an item that has been mentioned later carries a smaller degree ofcommunicative dynamism than another element that was mentioned at some earlier pointof the discourse, if in the present, i.e., repeated occurrence they both are contextuallybound.
In almost every text, of course, the situation is complicated by various factors. In a text
having the qualities of a work of art, there are deviations of different lypes possible. In atechnical text, the topic is, as a rule, rather complex, consisting of a relatively large
number of items activated partly by the text belonging to a certain domain of knowledge,
and partly by the relationship between technical terms known in this domain.
The relevance of the phenomena now descr bed as topic and focus, connected with thesemantics of word order, quantification, and negation (see also the remarks by Sparck
Jones and Kay, pp. 125 and 185) was one of the main linguistic topics of the 1973
Conference of Formal Semantics in Cambridge, U.K.* Also in some of the contributions
at the International Joint Conference on Artificial Intelligence in Tbilisi, 1975,
considerable attention was devoted to these questiors.** An approach using the conceptof stock of shared knowledge with its structure as briefly outlined above might be useful
not only in that it allows for handling meaning in terms of procedures (cf. the discussionof Winograd's work above and also Walker, p. 82), but, most of all in serving as a basis
for referential semantics in a sense similar to that of Winograd (pp. 134; 168ff). A nounphrase connected with the label ("grammateme") "definite" or "specific" (which should bepresent in the semantic representations of sentences) is understood as referring to an
object that is represented in the stock of shared knowledge. If this noun phrase has beenused in the topic of the utterance, its referent must be looked for amor.g theforegrounded elements of the stock of knowledge. The degree of communicative
dynamism carried by the noun phrase shows in any case whether the object referred to is
more or less foregrounded. These and other aspects connected with the proposed accountof topic and focus lead to a language sharing such advantages of some logical languages as
the existence of general inference procedures, but lacking the drawback of these languages
in that their assertions do not indicate how they should be used; see the Appendix.
Linguistic Aspects of Fact Retrieval
According to Damerau (1976, p. 1), linguistics has not had much influence on language
processing in fact retrieval systems. However, the (case) frames Damerau so often quotes
did come from linguistics (the linguist Fillmore formulated his case theory following
some insights of European structural linguistics). Furthermore, the question Damerau
raises on p. 6 — concerning the possibility of using frames not only in implementations•See for instance (he paper by Vcnnemann in Keenan (1975); a very important aspect of the semantics of
discourse is analyzed by Isard in the same volume.
••See especially the contributions by Mylopoulos ct al. (1975) and Vayncveyg (1975).

117

Petr Sgall
exploring toy worlds, but also in those corresponding to realistic situations - - concerns
basic linguistic issues. If implementation should concern a system the empirical adequacyof which was, to a certain extent, checked before actual programming, then such a system,
corresponding to realistic situations, hardly can be classed as not being linguistic. Schankand Winograd have derived their systems f r o m quite specific linguistic theories. Probably
Stevens and Rumelhart (quoted by Damerau, p. 9, as having presented a study "of syntax
rather than semantics") also have been inspired by linguistic studies in syntax (andsemantics), in other words, the impact of linguistics in fact retrieval cannot be ignored,
and how could it, when the content of a document, the meaning of utterances, theunderstandingof texts are involved.
What matters, however, is the fact that theoreti:al linguistics is not often used directly(or adequately) in fact retrieval, which appears, up to now, as a rather isolated, although
rapidly growing branch of linguistic engineering. We have already discussed some causesof this lack of contact, especially those connected with the lack of due understanding of
the importance of computational "applications" on the side of theoretical linguists. But,on the other side, as Sparck Jones and Kay have noted (p. 19£), at least in one aspect theonus is on the documentalist, who should provide a proper specification o f what he needs
to satisfy his retrieval objectives. Up to now it does not seem that an adequate (andsufficiently general) specification of these objectives - - either for fact or for document
retrieval - - has been achieved. A n d , ii is the speCialisr. in fact retrieval, who should be
able to use (at least, by means of a team cooperation) recent findings of linguistic theory,
even i f they have not yet found their way to the academic curriculum. If Damerau (p. 25)
draws an analogy between some of the artificial intelligence systems and the dreams ofalchemists, he may be right, but w i t h these systems, it is linguistic semantics that islacking, and some of its issues are by far more accessible today than those of chemistrywere f o r the alchemists some three or four centuries ago. In any case, the value of any
solution of a general problem in fact retrieval will depend, first of all, on the universalityof the solution. If the given approach is adequate and can be used without specificrestrictions (i.e., i f the conditions f o r its effective use have been stated already), then its
detailed elaboration is more or less a mere matter of routine. In the other case, i f we do
not yet know whether the approach can be transferred f r o m the restricted domain of agiven experiment to a universe of realistic situations, i.e., if we do not know where it ispossible to apply our approach, there always is the danger that sooner or later it will benecessary to resort to ad hoc solutions which might not be free of the risk that theapproach as a whole would be invalidated by them. A n d , furthermore, in the domain of
meaning, content, and uncerstanding natural language, it is precisely linguistic semantics
that should take the responsibility of the universality of the solutions. We attempted toshow in the last section that there are good reasons to state that linguistic semantics isprepared to bear this responsibility.
The universal solution is certainly not the cheapest, in the general case, and it might be
prudent not to use all of its force where this is not needed. To apply this way ofreasoning, however, one must know f i r s t the universal solution, and second, what parts or
aspects of it are not necess iry for the given task. Therefore, it would be more advisable toexperiment with more general procedures and systems, which should be reduced then toyield effective and economical models for commercial use. Unfortunately, the world is
not organized wisely enough, and one of the main goals of almost each of the scatteredexperimenting groups is to show in a relatively very short time that it is possible, using avery limited amount of preliminary work, to construct a practically useful system.
One of the main problems of fact retrieval seems to consist in v/hat has beencharacterized by Sparck Jones and Kay (p. 44) as decoupling. When higher types ofi n f o r m a t i o n systems are concerned, the task is not only to separate the language used tocommunicate with the core of the system f r o m the f o r m of the data store'and f r o m thelogical operations needed to manipulate it (since languages may change, while the data
should remain uncharged). In addition, the task is to f i n d for each of them its proper

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Perspective Paper: Linguistics
characteristics, including features that would make the given language as effective as
possible. One of the main conclusions of the developments of linguistic semantics, assummarized in the last section, consists in the advantages of having a specific language - the set of semantic representations - - between the natural language (serving as the input
and output larguage o f the whole system) and the language o f the stored i n f o r m a t i o n .
The latter language may well have the f o r m of cognitive or "semantic" networks, but it
appears d i f f i c u l t to get rid of such drawbacks as those quoted, in connection with these
networks, by Damerau (p. 4) f r o m Woods (the lack of distinction between extensional
and intensional, as well as asserted and hypothetical nodes, etc.), i f the corresponding
items in surface sentences, which may be used as cues to such distinctions, are left
without counterparts in the inner language of the system. It appears that the use of amore sophisticated linguistic framework, and also of a more reliable psychological basis(as is present in the cognitive networks of Hays, 1975) could be useful in these respects.
Also the distinction between the b u k of the data and its foregrounded part (in the senseof the previous section) should be provided for. The language of logical operations (or, inmore modern terms, of the brain of the system) might be connected with the existence ofgeneral inference procedures and other advantages of logical languages. Here we are in abetter situation than in the domain of linguistic semantics, since logical systems havebeen studied much more intensively. Thus, even i f "special natural deduction systems" areproposed f o r i n f o r m a t i o n systems (cf. Damerau, quoting Reiter, p. 7), it can be hopedthat the condition we have already mentioned w i l l be satisfied. In using a special systemf o r a restricted purpose, it can be checked relatively easily what has been left out f r o m auniversal system that is adequate without the special restrictions.
We can give here ( i n the Appendix) only a quite short characterization of the mainfeatures of a system of fact retrieval using the level of semantic representations and theirtranslations into a logical metalanguage which may be used by the brain.
Linguistics and the Future of

Programming

The overall aim of language processing is to make the computer understand humanlanguage as such. It is not necessary to describe formally all the variation of language
according to style, local dialects, affected speech, e.c, since most of this variation is not
likely to be used when computers are addressed.
T o put it quite simply, man-machine communication presupposes that one of its
participants has learned the other's language. This burden, hitherto carried by (computer)people, should be passed over to the computer alone.
If programming numerical tasks as well as other tasks not requiring a regularcommunicative interaction between man and machine are left aside f o r the moment, wemight state that the direct use of computers by specialists in other branches thancomputer science is not possible without such a development. What is needed, is acompiler for English and other natural languages. In any case, the significance of
linguistics f o r the future of artificial intelligence is connected with making programming
languages more and more human, i.e., making them include reasonable and expandable
subsets of natural ianguages.
Not only is programming as such involved, since i f a free conversation with the computerwere possible to a certain extent, many different degrees of man-machine cooperation
would emerge, some of them being more akin to the formulation of a program, others to
its use. As for the necessary and possible freedom in the use of natural language, two
extreme cases could be left out of consideration. On the one hand, the standard tasks thatare typical for certain areas of the current use of computers, like numerical tasks or
document retrieval, do not require a free use of natural language. On the other hand

11')

Petr Sgall
it may be assumed that the "informational explosion" and the automation of its handlingwill be connected with some requirements, concerning a standardization of their linguisticmeans, upon the authors of texts in this or that branch of technology, so that a "full"formalization of natural language can still remain beyond our dreams.
Thus it is possible, as for the domain of fact retrieval, to imagine a situation where theauthors writing about, say, electronics, or chemistry, etc., will be advised not to use
sentences longer than twenty words, the pronoun which without a preposition, theconjunction as in positions where because can be used instead, sequences of more than
two noun (or prepositional) phrases without an intervening verbal form, etc.* Otherwise
their texts will not be well understood by the system designed to construct and update theautomatic encyclopaedia of the given branch of technology, and customers using thissystem as a source of their information probably will not find and use the author's results.
Certainly, it will not be necessary for the authors cf texts themselves to take care ofrespecting the standardizing prescriptions. They will be aided by a more or less drastic
precditing since, in the first period of the foreseen epoch, the standardization rules may besomewhat complicated and some of them may require specific linguistic knowledge. But
the functioning of such systems itslef will yield more and more rough material andimpulese of various kinds (frequent types of errors at different levels, contextual
environments permitting criteria for their solution to be found, etc.) so that it will bepossible o conplemeni the parsers or compilers to such an extent that preediting will
eventually become superfluous. Some restrictions on the authors may even then benecessary, but these will be comparable to the requirements of standardization in otherfields. Thanks to their usefulness, they probably will not represent such a large burden for
the authors as the orthographic conventions of our times do.
It is already possible now in formulating research programs to reckon with the fact thatthe main attention should be concentrated on the syntactic and semantic analysis of aproperly chosen subset of the natural language, which soon might be able to occupy theplace of programming languages. Several contributions illustrating this development are
being prepared for the International Conference on Computational Linguistics in Ottawa,
July 1976.** These tendencies certainly will be supported by such factors as the increasing
accessibility of man machine interaction, in the course of which much of the ambiguity
and vagueness of natural language can be treated (thus yielding new material for further
developments in parsers).
Another aspect of the relationship between programming and linguistics consists in suchapproaches to automatic programming as Hedorn's (quoted by Damerau, p. 22), where
natural language is used in the input to describe a problem (a solution of which is to be
programmed), and also in one of the outputs, in which this problem is rephrased by thecomputer. As Damerau remarks, if such a system is tested with a real class of users, its
uti ity may be evaluated; and, we may add, such testing could be very important for
linguistic research. Every system using natural language, if used on a larger scale, willbring new possibilities for the refinement of linguistic frameworks.
As Walker (p. 74) states, the most significant effect on linguistics in the long term will
result not from computer use oriented directly toward linguistic aims, but from systems ofquestion answering or computer understanding. The interplay of factual knowledge and of•Or. to put it in a more practical way, such a sequence would always be analyzed as in "the drawer of thetable in the room of my secretary", rather than "book of adventures by Stevenson in my library".
"See especially the contributions by Burton and Woods on a compiling system for augmented trans: -n
networks, by Schlesinger, and by Landsbergen.

120Perspective Paper: Linguistics
linguistic competence, the different aspects of language use as changing the information
stored in memory, and also the ways of acquisition of language can be investigated bymeans of the study of such systems. Experiments with question answering systems andwith programming in natural languages will be of major importance for theoreticallinguistics. In this sense, the future of linguistics is closely connected with computerscience and information systems; but also the future of the latter disciplines cannot be
imagined without linguistics.
Appendix
Let us describe, as an example, the programme for man-machine communication being
prepared, step by step, by the group of algebraic linguistics of Charles University in
Prague. The algorithms being prepared can be divided into the following groups:(i) Grammatical analysis of input texts (i.e., of Czech and English texts onelectronics), yielding unambiguous semantic representations of subsequent
sentences (in the form of linearized dependency graphs).
(ii) Algorithms translating from the semantic representations (which still have alinguistic character) into a logical language, well adapted to the purposes of thetheory of inference, etc.; in this form the information gained from the natural
language input is to be stored in the computer memory (and confronted withfurther such information, gained later from other texts).
(iii) Algorithms looking for information needed according to questions formulatedby the users in Czech and English and anal>zed according to the algorithms of (i).
(iv) Algorithms for the synthesis of answers in Czech and English.
We want tD characterize the solution of two problems that appeared crucial for (i) and(ii), as well as for the form of the semantic representations (SKs) of sentences (thelanguage serving as the output of (i) and input of (ii), among other purposes).
The chosen linguistic approach is connected with the following form of SR's (where every
A stands for a lexical unit, accompanied, possibly, by markers of "morphologicalmeanings" (grammatemes), such as Plural, Preterite, etc., the subscript denoting thefunction of the given item in the sentence: Actor, Objective, Dative, Place, Direction, etc.):(1) V (Aj. A>

A» A wA„)

Each of the participant, denoted here as Ax, can of course itself consist in a g roup
headed by the verb, so that a structure of the shape (1) may be embedded, under certain
conditions (specified by a generative grammar using dependency syntax) into another such
structure. The superscript b is attached to those elements that are contextually bound, i. e.,
included in the topic; the others constitute the comment or the focus of the sentence.*
Th< topic/focus dichotomy is treated here along the lines we have already characterized
above for the empirical background; this also concerns the position of the negation
operator. If one takes into account also the delimiting features (such as Definite,•This tecto!',rammatical level, the set of SR's of this shape, could serve also as an inte lingua for automatictranslation; certainly, in many details of the lexicon and also in some features concerning the grammatemes
and other items of the syntax of this level, languages differ. It is necessary to treat such differences in a way
similar to that in which idioms are treated in binary translation. For a relatively detailed characterization of
the tectogrammatical level, cf. Sgall et al. (1969). Klein and Stechow (1974), Sgall ct al. (1975).

121

Petr Sgall
Indefinite, Specifying) the shape of an SR as given in (1) should be complemented in thef o l l o w i n g way:(2) V n , 0 « P , a m | ) J ] , (P 2 a nl2 )E 2

(Pj amj)J, (Pj+1 a , ^ ) ^

<P„

a^)^)

where the indices of the f o r m nij specify lexical units, the indices of the f o r m kj specify
the "cases" (participants, syntactic functions) and P, stands f o r one of the operators SPEC,D E F , I N D E F , EV, FEW, M A N Y , i. e., f o r d e l i m i t i n g features (understood here in thesense o f Bier^isch; f o r a discussion cf. Krizek, 1973; for the purpose o f our present
discussion, we also cl iss here every, many, and few as d e l i m i t i n g features). The f o r m u l a(2) represents an SR of a sentence with a contextually non-bound verb; i f the verb iscontextually bound, then V is attached a superscript b.
T o formulate a procedure translating (2) to the predicate calculus, we have introduced a
new operator St x (read as: " f o r x such that ..."). St is an operator with a free number ofarguments; in its nature, it is close to the epsilon operator but it is generalized f o r agreater (arbitrary, but f i n i t e ) number c f name arguments having a set character. We write
St(x)(F(x))(G(x)),
to be read " f o r any x for which F(x) holds, G(x)holds", which
can be compared with Russell's G(x(F(x)),
and x stands for a sequence of set namevariables (where no ambiguity can arise, we do riot distinguish the name o f an elementf r o m that of the set having only this one element).
The first step of this translation procedure, determined by Rule T, depends on whether theverb occurring in the given SR is or is not contextually bound.
Rule T: If the SR has the shape (2), it is rewritten as (3); i f the SR differs f r o m(2) only in that V has the superscript b, the SR is rewritten as (4):(3) St ( x k l , Sx ) ( a „ M (*[\)<vm„ <R> & \J*W
<">

St

<V \2
(St (*»„,&R) (a& . . . & a m , ( x ^ ) ) (St (R, x ^• • •* "m„ ofrXRfr,\-»l ^\ ) (R("i

& a

(x

&

xk|))

*„)))
&

"-2 k2> • • • S (Xk? & V ( R ) )%)) (a mjtl (H\:\) & • •• & amn (xj»»)

Note: It would be more accurate i f the superscript denoting the delimiting operator thatbinds the variable x k ( i = 1,2n) were included also in the f i r s t parenthesis f o l l o w i n g
the symbols St or R; but no misunderstanding can arise here.
Afterwards we eliminate, step by step, the occurrences of the symbol St ( f o r a technicalpresentation of the whole procedure, cf. Sgall, Hajicova and Benesova, 1973, pp. 199-203)
in such a way that it is replaced by one of the usual quantifiers (determined by the given
delimiting feature). After other modifications stated in an algorithmic f o r m , a formula ofthe second order predicate calculus results (see the examples in the quoted book; also
Hajicova et al., 1975).
If an SR contains the symbol Neg, Rule T is applied first, disregarding Neg; afterwards,(a) If Nog has not been assigned the supeiscript b, then the symbol N O N ( f o r logicalnegation) is written to the left of the translation of the string G(w) in the formula
representing the result of the application of T to the given SR.
(b) If Ncg b is present in the translated SR (with Vb), then N O N V instead of V is written
in the resulting formula.

122

Perspective Paper: Linguistics
The elimination of the operator St leads to the common form of formulae of predicate
logic. If tlis operator (defined for instance by means of an axiom) is retained, one of the
drawbacks of predicate logic, well known in the domain of artificial intelligence (asWinograd also quoted in his study), can be removed. The formula in its common form
does not point out how it should be used, while the corresponding representation using theoperator St denotes explicitly the distinction (and the boundary) between topic and focus.
(The importance of this from the viewpoint of his "imperative form" of semantic
representations, Winograd clearly shows in the case of input questions, as we have alreadyseen.) Thus we are informed directly what parts of the information concerned should be
only ideniified (in the activated part of the robot's storage), and what parts of the SR
should be used to modify that "given" information.
To be even more specific, let us quote an example from a logical discussion, where thisdrawback of the formulae can be illustrated (this example is far from belonging to thosein which the quoted drawback could lead to real difficulties). If, e.g., Suppes characterizes
P, the set of rules of a context-sensitive grammar, by P being included in VJ x V+ (where
V+ = V* - {0}), and the corresponding set connected with a context-free grammar by P
being included in V N x V + , then the reader must compare all the symbols of bothformulae to find the difference. If, instead, the latter formula is written in a shapecorresponding not just to "P is a part of the Cartesian product of V N and V+", but to"(here) it is V N , the Cartesian product of which with V + includes P", the symbol V N isunambiguously characterized as the (only part of) focus of the given assertion, and, in thisway it is pointed out that the relevant distinction concerns this symbol and its counterpart
in the former formula. The identification of this counterpart is much easier than a generalsearch for the relevant distinction, which would be necessary if the common shape of theformulae were used. Clearly, with more complicated (sets of) assertions, differences of thiskind would be much more pronounced.
Thus, our example shows how it is possible to translate sentences into representations
which are close enough to predicate logic for its laws of inference, etc., to be applicable
almost directly, but which lack some of its drawbacks.
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