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<Paper uid="P98-1056">
  <Title>Syntactic and Semantic Transfer with F-Structures*</Title>
  <Section position="7" start_page="344" end_page="345" type="concl">
    <SectionTitle>
5 Discussion
</SectionTitle>
    <Paragraph position="0"> We have presented two alternative architectures for transfer in LFG. In both cases, transfer is driven by the transfer module developed and implemented by Dorna and Emele (1996a). In the case of syntactic transfer, transfer is defined on term representations of f-structures. In the case of semantic transfer, transfer is defined on UDRS translations of f-structures. Fstructure, term and UDRS correspondences are defined in the Appendix. The transfer rules are bi-directional, as are the f-structure-term and f-structure-UDRS correspondences.</Paragraph>
    <Paragraph position="1"> Co-description based approaches (Kaplan and Wedekind, 1993) require annotation of source and target lexica and grammars. By contrast, both approaches presented here support modular grammar development: they don't involve additional coding in the grammar specifications.</Paragraph>
    <Paragraph position="2"> An important issue, noted above, is the problem of ambiguities and ambiguity preserving transfer. F-structures and UDRSs are underspecified syntactic and semantic representations, respectively. Both support ambiguity preserving transfer to differing degrees (NP scope, operators, adjuncts). F-structure based syntactic represen- null tations may come up against structural mismatches in transfer. The original co-description based approach in (Kaplan et al., 1989) faced problems when it came to examples involving embedded head-switching and multiple adjuncts (Sadler and Thompson, 1991), which led to the introduction of a restriction operator, to enable transfer on partial f-structures or semantic structures (Kaplan and Wedekind, 1993). One might suppose that the need to refer to partial structures is an artifact of the correspondence-based approach, which doesn't allow the mapping from a single node of the source f-structure to distinct nodes in the target f-structure without violation of the functional property of the correspondence. On closer inspection, though, the rewriting approach to syntactic f-structure-term translations presented above suffers from the very same problems that were met by the correspondence-based approach in (Kaplan et al., 1989).</Paragraph>
    <Paragraph position="3"> By contrast, transfer on the semantic UDRS representations does not suffer from such problems. Head switching is dealt with in the construction of semantic representations. Under-specified semantic representations in the form of UDRSs (or related formalisms) offer the following advantanges for transfer: they abstract away from cross-language configurational variation to facilitate transfer. Unlike the original restriction operator approach (Kaplan and Wedekind, 1993) whenever possible they avoid the detour of multiple transfer on disambiguated representations. At the same time they provide a flexible encoding of information essential to steer transfer. null Of course, semantics does not come for free nor does it always blend as seamlessly with syntactic representations as one would hope for. Semantics has to be encoded in the grammar or defined in terms of correspondences as below.</Paragraph>
    <Paragraph position="4"> System design has to address the question where to do what at which cost. Semantic representations pay off when they are useful for a number of tasks: evaluation (as against a database), inference and transfer. Even more so when existing resources can be interfaced qua semantic representations: in our case the tested transfer methodology and resources developed in (Dorna and Emele, 1996a).</Paragraph>
  </Section>
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