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The translation of anaphoric relations
In this section, we intend to give an impression of the usefulness of coindex relations in translation and the translation of the relations themselves. In linguistics, a monolingual account of coindexation is quite an achievement. In machine translation, the most important part of research deals with the translation of the relations that were established monolingually.
The I-object to be translated consists of an I-structure annotated
with anaphoric relations. An I-object is the result of
the application of certain anaphoric relations (denoted by the
annotations) to a particular I-structure. The compositional
translation of an I-object is the result of the application of the
translated annotations to the translated I-structure. We
hold the view that anaphoric relations are universal in MiMo. The
translation of a relation between the I-structures I and J is that same
relation between the translations of I and J. This is summarized in
(29).
(29) the translation of an I-object:
The translation of an I-object I1 is the result of the application of
the translations of the annotations of I1 to the translation of I1's
I-structure.
The translation of an annotation R(I,J) is R(t(I),t(J)).
The final set of anaphoric relations of the target object should be
equivalent to the set that existed at the source level. The following
example illustrates principle (30) :
(30) Por que [ dice Juan [ que [ los dos creian [ que [ Pedro habia pensado [ que [ el grupo habia aplazado la reunion
Why say John that the two thought that Peter
believed that the group postponed the meeting
Inversion being obligatory in all clauses except the lowest, 'por que'
can only bind the modifier position in either the first or the second clause.
Each relation further down is excluded as more clauses would have to show
inversion then. When we ignore the bindings established at the Spanish
I-level, translation into English will produce a lot of possible
translations since 'that' may or may not be inserted in every
complementizer position in English. However, the impact of this
complementizer on possible anaphoric relations is not totally
irrelevant. According to WAHL (1987), the complementizer blocks
binding of 'why' to an empty position deeper down, cf. (31) and (32).
(31) why(i)/(j) do you think _(i) the boat sank _(j)
(32) why(i) do you think _(i) that the boat sank _
When we preserve the bindings from Spanish and we claim that
in English 'that' may never be inserted when its modifier position is bound to an
antecedent, we can deterministically arrive at the right translation :
(33) Por que [ dice Juan [ que [ los dos creian [ que [ Pedro habia pensado [ que [ el grupo habia aplazado la reunion
(34) Why [ did John say [ [ the two thought [ that [ Peter believed [ (that) the group had postponed the meeting
Both are ambiguous since both can question the reason for
John's 'saying it' and 'the two believing it'. Other interpretations are
excluded in both Spanish and English.
Definition (29) also causes some problems.
Take the following example from Italian
(cf. Chomsky 1981) :
(35) l'uomo [che mi domando [chi abbia visto]]
the man(i) of whom I wonder who(j) e(i) saw e(j)
One might wonder what the English translation would have to be in the
first place. In MiMo, the incorrect literal translation will not be
found because the necessary anaphoric relations cannot be
established. In cases like these, separate translation rules are
needed to arrive at a translation of (35). It is possible to
refer explicitly to anaphoric relations as long as they are
restricted in depth. This is necessary in case an expression
without anaphoric relations translates into one which requires a
linking between an antecedent and an anaphor. An example is (36).
(36) Jan zwemt graag 
John(i) likes _(i) to swim
Unboundedly deep embedded relations
are however not accessible by translation rules in the transfer
component.
Another problem we face deals with the interaction of anaphora and
other standard 'non-compositional' phenomena, such as the example of
Dutch 'graag' translating as 'to like' in English (see section 1).
These examples, as well as anaphora, can be handled compositionally,
as we have shown.
The interaction however poses some problems, see (37).
(37) Hoe graag zwom Jan How much did John like to swim
Since 'graag' is displaced, translation of 'graag' as the exceptional
part of the embedded sentence is not possible, given that the movement is
not undone
.
These cases are even noncompositional from
MiMo's tolerant view on compositionality.
Next: Conclusion Up: AN APPROACH TO SENTENCE-LEVEL Previous: Implementation
Gertjan van Noord
Fri Nov 25 13:16:14 MET 1994