11. The method of claim 6 , where the variation of context in which the sequence occurs, HP(S), is calculated as 
 HP ( S )=MIN( HLP ( S ), HRP ( S )) where MIN defines a minimum operation, S represents the sequence, HLP(S) is defined as the number of continuations to the left of the sequence that cover a predetermined percentage of all cases in the collection of documents and HRP(S) is defined as the number of continuations to the right of the sequence that cover the predetermined percentage of all cases in the collection of documents.
6. The method of claim 1 , where the variation of context in which the sequence occurs is calculated relative to a collection of documents.