THE TRANSFER OP FINITE VERB FORMS IN A MACHINE 
TRANSLATION SYSTEM 
Bente Maegaard 
Institut for anvendt og matematlsk lingvlstik, 
K~benhsvns Universltet 
NJalsgade 96, DK-2300 K~benhavn S, De:m~ark 
This paper is based on work done Jointly by Hanne Ruus, Ehbe 
Spang-Hanssen and the author, all of the University of Copen~ 
hagen. The work was done within the framework of EUROTRA and 
sponsored by the Commission of the European Community. Work 
on this paper was begun whilst the author was at ISSCO, 
Genev a. 
Throughout this paper we shall imagine a machine trans- 
lation system which performs the following: correct analysis 
of source language, correct structure of target language sent- 
ence, correct choice of words in the target language. In this 
enviro~.ent we shall discuss some aspects of the problem of 
constructing the correct finite verbal form. The languages in- 
volved are the languages of the European Community. It is 
obvious that it is not possible simply to use the "same" 
morphological form in the target language as in the source 
language: verbal tenses are not the same in all languages 
(not even in languages as closely related as those considered) 
and even where the same tenses exist they do not necessarily 
have the same distribution. So a mapping has to be defined. 
AS EUROTRA is in its conception multilingual this mapping 
should not be defined on a binary basis (between pairs of 
languages), but should rather consist in a definition of some 
basic and global interpretations of the morphology of verbs in 
the languages considered. 
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The study can.not be restricted to morphology proper. 
Meanings that are expressed morphologically (by auxiliaries 
or flexives) in one language might be expressed lexically (by 
the use of particular lexical units) in other languages. As an 
example~ take the progressive aspect in English: En. they are 
~it_~_i~_n~ -~ Fr. ils 4crivent / ils @ont en train d'4crire, --~ 
--~ Danish de skTiver / de sidder cg skriver / de er i f~rd 
wed at ~krlve.l.e. the progressive aspect which is expressed 
in English by morphological mesns, is in French and Danish 
either not expressed or expressed by certain lexical units. 
It is very important to realize the impact of this, There 
is often a tendency to think that in the analysis of language 
a borderline can be drawn between morphological information 
and lexioal information. This is true to s large extent when 
only one language is considered, but it is certainly not true 
in a multilingual environment. Roughly speaking, the system 
should take into account all pieces of information which can 
be expressed morphologically in at least one language. 
The propose~ e.yetem for the representation of verbal forms. 
The system as such will contain the global information, 
i.e. the information which has to be transferred to other 
languages. In this paper only the transfer of active finite 
verb forms with respect to tense will be considered, i.e. 
modality, voice, etc. is not taken into account. 
Apart from this global information the system can for 
each language be expanded with all kinds of local information 
which is useful for analysis or for generation. Some morpho- 
logical phenomena are only grammatically bound and do not 
carry any semantic meaning that should be coded for the use 
of other languages, e.g. the use of the subjonctif in French 
subordinate clauses following ll faut que. Information about 
this subjonctif can be regarded as internal to French and 
should not be expressed in the global system. 
The variables proposed to describe the semantic content 
of tense and aspect are the following (Note that tens_...._ee is 
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used in a very general meaning. Tense is determined by values 
of time and aspect. It should also be noted that the use of 
the concepts aspect and Aktionsart has been de£indd with 
respect to the languages involved and consequently is not 
necessarily the traditional one): 
TENSE ::s (AXIS, PROSPECTIVE, RETROSPECTIVE, ASPECT, 
AKTIONSART ) 
AXIS :'- l~C \[ TU~C 
PROSPECTIVE z -- PROSPECT- I PROSPECT+ 
RETROSPECTIVE : := RE~RO- I RETRO+ ~ CONTINUOUS I """ 
ASPECT : :. nul._.~l ~ EMPHATIC PROGRESSIVE 
AKTIONSART ::= DURATIVE ~ NON-DURATIVE 
Suggestions of other values (for English, for the examples 
below) : 
AKTIONSART ::= DYNAMIC ~ STATIVE or perhaps rather 
ACTIVITY VERB ~ PROCESS VERB I TRANSITIONAL 
EVENT VERB 
For adverbs a value TIMEWI~lq. 
In the paper the use of the variables and their values 
will be explained. Here only a few remarks can be made. 
1. The system is viewed as operating in all languages on 
two time axes, one for the tenses that are anchored in the 
present, and a parallel one for the tenses that are anchored 
in the past (NUNC and TUNC, respectively), 
2. The RETROSPECTIVE value CONTINUOUS is used for events 
that are still going on: F~. il demeure la depui~ un mois 
end En. He has l~.ved there fo r" a month will get the same 
values: (I~NC, PROSPECT-, CONTINUOUS, null, DURATIVE). 
3. More values for the RETROSPECTIVE variable is to be 
foreseen. 
4. In English it is not possible to have the prefect tense 
with an adverbial of the type TIMEWHEN. So a rule of the 
generation ~smmar of English will say that (~UNC, PROSPECT-, 
RETRO+ ..,..) + TI~WHEH -~ (TUNC, PROSPECT-, RETRO-,..,..) 
5. Certain verbs in English tend to prefer the progressive 
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aspect. Consequently the AKTIONSART must be expanded as to be 
able to express these facts: 
A simulation of the system made on some Community texts 
shows good results. 
A text is shown in the appednix An French (source) and 
in English. Both versions are official Community texts. For 
each verbal form which is finite in French and has a finite 
equivalent in English is shown how the system works. 
a adopt ~ (NUNC, PROSPECT-, RETRO+, null, NON-DURATIVE) + 
. ~u~.WH~N --@ 
a ~t___~ (~NUNC, PROSPECT-, KETRO+, null, DURATIVE) + 
+ TIMEWHEN ---~ wa.~s 
a au~nent~ --~ ros_._e 
(NB. The TIMEWHEN value from the previous sentence must 
be used, otherwise we get the prefect tense) 
a @t..___~ -~ wa_~s (because of TIMEWHEN) 
ont ~t6 -@ have been 
ont baiss~ (NUNC, PROSPECT-, RETRO+, ..., DURATIVE) ÷ 
+ TRANSITIONAL EVENT VERB -9 have been fallin~ 
~'est d~t~rior@e as above, with the AKTIONSART being PROCESS 
VERB --> has been deterioratin~ 
~ont tombte a. (NUNC, PROSPECT-, RETRO+, ..., NCN-DURATiVE) -9 
-~ have dropp@d to 
(NB. the English version in fact has dropped to, but as 
there is no TIMEWHEN this is not possible to obtain 
with the system. However it is possible to choose 
both translations from the French original. 
Note furthermore, that tombe_.__~r in the meaning "decrease" 
is DURATIVE, while tomber~a is NON-DURATIVE). 
To our knowledge no other system has been proposed which 
works for more than one language. Reichenbach's system is made 
for English and shows deficiences even for English. Bruce "s 
system repairs these deficiences and works for English, but 
relies heavily on the structure of English verbal forms and 
cannot easily be brought to work for other languages as well. 
- 193 - 
The system which we have proposed seems promising, but still 
a good deal of work is needed to define adequate values for 
the different variables. 
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APPENDIX 
Charbon 
2oi.96. La Commission a adopt6 le 19 avril 1979, apres 
consultation du Comit4 consul%atif OEOA (Bull. CE 3-1979, 
point 2.3.75), le rapport annuel sum le march~ charbonnier de 
la Commumaut4 en 1978 et see perspectives pour 1979 (JO C 120 
du 14.5.1979). 
Avec quelque 287 millions de tonnes, la consommation de 
charbon a ~t~ environ la m~me en 1978 q~'en 1977, oependant 
q~e. la oo~atlon du charbon destin~ a la production 
d 61ectricit6 a au~nent~ de 5~ environ pour atteindre 159 
millions de tonnes environ en 1978 contre 151 millions de 
tonnes 1 annie pr~c~dente. Avec 238 millions de tonnes environ 
la production d~ charbon de la Communaut~ en 1978 a 4t6 in- 
f~rieume de l~ a cells de 1977; elle ee caract~rise surtout 
par une 16g~re augmentation de la production au Royaume-Uni 
et par de l~ger, reculs ailleurs. 
Les hausses de prlx du charbon de la Communaut~ ont ~t~ 
modifies. Toutefois, comme les prix du march~ mo~xprlm~s 
dans la p~upart des monnaies de la Communaut~ ont balsa6 du 
falt de 1 affaiblissement du dollar am~rioqin, la position con- 
ourrentielle du charbon de la Communaut~ s est d~t~rior6e 
oonsid~rablement. N~amnoins, les importatfons de charbon en provenance de pays tiers ont dimlnu~ de 1,5~ et sont tomb~e~ 
a 45 millions de tonnes, dont plus de la moiti~ de charb6n vapeur. 
Coal 
2.1.96. After consulting the ECSO Consultative Committee 
(Bull. EC 3-1979, point 2.3.75), on 19 April the Commission ~ 
the annual report on the Communi~ coal market in 1978 
forecasts for 1979 (OJ C 120 of 14.5.1979). 
At around 287 million tonnes coal consumption was about the 
same in 1978 as in 1977, while consumption for-6Tectrlcity 
generation rose by about 58 to reach roughly 159 million t in 
1978 as oom~-~d with 151 million t the previous year. Commun- 
was ity coal production in 1978"I~ma about 238 million t or some 
18 lower than in 1977, the features being a slight rise 
in production in the UK and slight drops elsewhere. 
Price increases of Community coal have he qn moderate. However, 
as world market prices expressed ih most Community cttrrencles 
have been fallin~ because of the weakening of the US dollar, 
the competitiveness of Community coal has been deterioratin~ 
considerably. Nevertheless, coal imports from third countries ~o 
bY about 1.5% to 45 million t, of which over half was 
alo 
- 195 - 

References 

Bruce: A Model for Temporal References and Its Application 
in a Question Answering Program. Artificial Intelligence 
1972, vol 3, PP 1-25. 

Greenbaum, Quirk, Leech, Svartvik: A Qramm~r of Contemporary 
E~lish. Longman. London 1976. 

Maegaard, Ruus, Spang-Hanssen: Investigation of the Verbal 
S2stemfor.EUROTRA, Report for the EEC, 1981. 

Reichenbach: Elements of S~mbolic LoKic. Macmillan. New York 
1947, pp 287-298. 
