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<Paper uid="J94-3004">
  <Title>The Reconstruction Engine: A Computer Implementation of the Comparative Method</Title>
  <Section position="1" start_page="0" end_page="0" type="abstr">
    <SectionTitle>
CNRS, Paris
</SectionTitle>
    <Paragraph position="0"> We describe the implementation of a computer program, the Reconstruction Engine (RE), which models the comparative method for establishing genetic affiliation among a group of languages.</Paragraph>
    <Paragraph position="1"> The program is a research tool designed to aid the linguist in evaluating specific hypotheses, by calculating the consequences of a set of postulated sound changes (proposed by the linguist) on complete lexicons of several languages. It divides the lexicons into a phonologically regular part and a part that deviates from the sound laws. RE is bi-directionah given words in modern languages, it can propose cognate sets (with reconstructions); given reconstructions, it can project the modern forms that would result from regular changes. RE operates either interactively, allowing word-by-word evaluation of hypothesized sound changes and semantic shifts, or in a &amp;quot;batch&amp;quot; mode, processing entire multilingual lexicons en masse.</Paragraph>
    <Paragraph position="2"> We describe the algorithms implemented in RE, specifically the parsing and combinatorial techniques used to make projections upstream or downstream in the sense of time, the procedures for creating and consolidating cognate sets based on these projections, and the ad hoc techniques developed for handling the semantic component of the comparative method.</Paragraph>
    <Paragraph position="3"> Other programs and computational approaches to historical linguistics are briefly reviewed.</Paragraph>
    <Paragraph position="4"> Some results from a study of the Tamang languages of Nepal (a subgroup of the Tibeto-Burman family) are presented, and data from these languages are used throughout for exemplification of the operation of the program.</Paragraph>
    <Paragraph position="5"> Finally, we discuss features of RE that make it possible to handle the complex and sometimes imprecise representations of lexical items, and speculate on possible directions for future research.</Paragraph>
  </Section>
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