Abstract: The present invention provides a dialogue system in which semantic ambiguity is reduced by selectively choosing which semantic structures are to be made available for parsing based on previous information obtained from the user or other context information. In one embodiment, the semantic grammar used by the parser is altered so that the grammar is focused based on information about the user or the dialogue state. In other embodiments, the semantic parsing is focused on certain parse structures by giving preference to structures that the dialogue system has marked as being expected.

Abstract: A method of calculating trigram path probabilities for an input string of text containing a multi-word-entry (MWE) or a factoid includes tokenizing the input string to create a plurality of parse leaf units (PLUs). A PosColumn is constructed for each word, MWE, factoid and character in the input string of text which has a unique first (Ft) and last (Lt) token pair. TrigramColumns are constructed which define corresponding TrigramNodes each representing a trigram for three PosColumns. Forward and backward trigram path probabilities are calculated for each separate TrigramNode. The sums of all trigram path probabilities through each PLU are then calculated as a function of the forward and backward trigram path probabilities. Systems and computer-readable medium configured to implement the methods are also provided.

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.

Abstract: A method factors an ambiguous finite state transducer (FST) into two finite state transducers. The first FST is functional (i.e., unambiguous). The second FST retains the ambiguity of the original FST but is fail-safe (i.e., no failing paths) when applied to the output of the first FST. That is, the application of the second FST to an input string never leads to a state that does not provide a transition for the next symbol in the input. Subsequently, the first FST can be factorized into a left-sequential FST and a right-sequential FST that jointly represent a bi-machine.

Abstract: A method factors an input finite state transducer (FST) with unknown symbols into a left-sequential FST and a right-sequential FST while avoiding direct factorization of the unknown symbols. The left-sequential FST is formed by replacing each occurrence of the unknown symbol in the input FST with a sequence of the unknown symbol and a diacritic. The right-sequential FST is formed by replacing each occurrence of the diacritic with a symbol representative of an empty string and an output symbol.