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<Paper uid="W06-1501">
  <Title>References</Title>
  <Section position="7" start_page="5" end_page="5" type="evalu">
    <SectionTitle>
6 Experimental Results
</SectionTitle>
    <Paragraph position="0"> While our approach does not rely on any annotated corpus for LA, nor on a parallel corpus MSA-LA, we use a small treebank of LA (Maamouri et al., 2006) to analyze and test our approach. The LA treebank is divided into a development corpus and a test corpus, each about 11,000 tokens (using the same tokenization scheme as employed in the MSA treebank).</Paragraph>
    <Paragraph position="1"> We rst use the development corpus to determine which of the transformations are useful. We use two conditions. In the rst, the input text is not tagged, and the parser hypothesizes tags. In the second, the input text is tagged with the gold (correct) tag. The results are shown in Table 1.</Paragraph>
    <Paragraph position="2"> The baseline is simply the application of a pure MSA Chiang parser to LA. We see that important improvements are obtained using the lexical mapping. Adding the SVO transformation does not improve the results, but the NEG and BD transformations help slightly, and their effect is (partly)  periments on input without POS tags.) The evaluation on the test corpus con rms these results. Using the NEG and BD transformations and the small lexicon, we obtain a 17.3% error reduction relative to the baseline parser (Figure 2). These results show that the translation lexicon can be integrated effectively into our synchronous grammar framework. In addition, some syntactic transformations are useful. The SVO transformation, we assume, turns out not to be useful because the SVO word order is also possible in MSA, so that the new trees were not needed and needlessly introduced new derivations. The BD transformation shows the importance not of general syntactic transformations, but rather of lexically speci c syntactic transformations: varieties within one language family may differ more in terms of the lexico-syntactic constructions used for a speci c (semantic or pragmatic) purpose than in their basic syntactic inventory. Note that our tree-based synchronous formalism is ideally suited for expressing such transformations since it is lexicalized, and has an extended domain of locality. Given the impact of the BD transformation, in future work we intend to determine more lexico-structural transformations, rather than pure syntactic transformations. However, one major impediment to obtaining better results is the disparity in genre and domain which affects the overall performance. null</Paragraph>
  </Section>
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