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<Paper uid="P06-1123">
  <Title>Empirical Lower Bounds on the Complexity of Translational Equivalence [?]</Title>
  <Section position="2" start_page="0" end_page="0" type="abstr">
    <SectionTitle>
Abstract
</SectionTitle>
    <Paragraph position="0"> This paper describes a study of the patterns of translational equivalence exhibited by a variety of bitexts. The study found that the complexity of these patterns in every bitext was higher than suggested in the literature. These findings shed new light on why &amp;quot;syntactic&amp;quot; constraints have not helped to improve statistical translation models, including finite-state phrase-based models, tree-to-string models, and tree-to-tree models. The paper also presents evidence that inversion transduction grammars cannot generate some translational equivalence relations, even in relatively simple real bi-texts in syntactically similar languages with rigid word order. Instructions for replicating our experiments are at</Paragraph>
  </Section>
class="xml-element"></Paper>