Patent ID: 7509296

Claim:
A computer-implemented dialogue learning system for teaching a language which automatically generates from a correct expression of a sentence a plurality of incorrect expressions of the sentence, the system comprising: a template-template that contains within itself a plurality of templates and a plurality of nodes marked with label symbols that are associated with extraction rules, said system including a plurality of error rules by which the template-template can be expanded by adding a plurality of incorrect expressions of the sentence thereto as defined by the error rules, said extraction rules extracting a template from said template-template by including, excluding or modifying certain nodes of said template-template based on a value of the label symbols marking said nodes, said extracted template including at least one correct expression of the sentence and a plurality of incorrect expressions of the sentence, said system, by automatically defining a plurality of common incorrect expressions of the sentence according to the error rules, providing for automatic diagnosis of grammatical errors committed by a learner, each of said extraction rules being associated with a set of said label symbols (s 1 , s 2 , . . . s n ), with each symbol in said set being assigned one or more values, the values including at least one of an error message and a speech tag.