Method and apparatus for reducing the intermediate alphabet occurring between cascaded finite state transducers
First Claim
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1. A method for removing redundant intermediate symbols from a first factor having an output side and a second factor having an input side, comprising:
- identifying a plurality of non-overlapping equivalence classes of input symbols that are diacritics on the input side of the second factor;
representing each of the plurality of non-overlapping equivalence classes with a unique symbol;
replacing on the output side of the first factor and on the input side of the second factor each occurrence of a diacritic that appears in one of the plurality of non-overlapping equivalence classes with the unique symbol that represents the corresponding equivalence class; and
minimizing the first factor and the second factor.
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Abstract
A method reduces the number of diacritics and other intermediate symbols occurring between two factors that result from any factorization such as extraction of infinite ambiguity, factorization of finitely ambiguous finite-state transducer, or bimachine factorization. The method a posteriori removes all redundant intermediate symbols. The method can be used with any two finite-state transducers (FSTs) that operate in a cascade. With longer cascades, the method can be applied pair-wise to all FSTs, preferably starting from the last pair.
13 Citations
15 Claims
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1. A method for removing redundant intermediate symbols from a first factor having an output side and a second factor having an input side, comprising:
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identifying a plurality of non-overlapping equivalence classes of input symbols that are diacritics on the input side of the second factor;
representing each of the plurality of non-overlapping equivalence classes with a unique symbol;
replacing on the output side of the first factor and on the input side of the second factor each occurrence of a diacritic that appears in one of the plurality of non-overlapping equivalence classes with the unique symbol that represents the corresponding equivalence class; and
minimizing the first factor and the second factor. - View Dependent Claims (2, 3)
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4. A method for removing redundant intermediate symbols from a first finite-state transducer (FST) having an output side and a second finite-state transducer (FST) having an input side, comprising:
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identifying a plurality of non-overlapping equivalence classes of input symbols that are diacritics on the input side of the second FST;
representing each of the plurality of non-overlapping equivalence classes with a unique symbol;
replacing on the output side of the first FST and on the input side of the second FST each occurrence of a diacritic that appears in one of the plurality of non-overlapping equivalence classes with the unique symbol that represents the corresponding equivalence class; and
minimizing the first FST and the second FST. - View Dependent Claims (5, 6, 7, 8, 9)
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10. An apparatus for removing redundant intermediate symbols from a first FST having an output side and a second FST having an input side, comprising:
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means for identifying a plurality of non-overlapping equivalence classes of input symbols that are diacritics on the input side of the second FST;
means for representing each of the plurality of non-overlapping equivalence classes with a unique symbol;
means for replacing on the output side of the first FST and on the input side of the second FST each occurrence of a diacritic that appears in one of the plurality of non-overlapping equivalence classes with the unique symbol that represents the corresponding equivalence class; and
means for minimizing the first FST and the second FST. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification