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process is not of interest for us, as the only thing that will be used is the 102 dictionary. 103 

The patterns contained in the dictionary D ( x ) are then sorted in ascend- 104 ing alphabetical order to enable the binary search of each pattern in time 105 O ( logN ), where N is the number of entries in D ( x ). The dictionary is finally 106 stored for future use: this procedure may be carried out offline and has to be 107 performed only once for each data instance. Whenever a string x is checked 108 against a database containing n dictionaries, a dictionary D ( x ) is extracted 109 from x as described and matched against each of the n dictionaries. The 110 FCD between x and an object y represented by D ( y ) is defined as: 111 

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where | D ( x ) | and | D ( y ) | are the sizes of the relative dictionaries, repre- 112 sented by the number of entries they contain, and ∩ ( D ( x ) ,D ( y )) is the num- 113 

