2. The method of claim 1 , said knowledge derived from said historical conversational transcripts comprising: clustering textual segments in said historical conversational transcripts into groups of related textual segments; representing each of said groups of related textual segments by a representative syntax; forming a sequence of said representative syntax for each historical conversational transcript; finding frequently occurring subsequences from said sequence of representative syntax; and finding distinct and long frequently occurring subsequences from said frequently occurring subsequences.
5. The method of claim 2 , each said sequence of representative syntax comprises a segment of conversational transcripts belonging to each of said groups of related textual segments.