3. The method of claim 2 , further comprising calculating the first numerical value using an equation having a form: 
 P ( a,b,c,d,e,f , . . . )= P ( a ) P ( b|a ) P ( c|a,b ) P ( d|a,b,c ) P ( e|a,b,c,d ) P ( f|a,b,c,d,e )= P ( a ) P ( b|a ) P ( c|a,b ) P ( d|b,c ) P ( e|c,d ) P ( f|d,e ), wherein terms having the form P(a) correspond to a uni-gram probability, terms having the form P(b|a) correspond to a bi-gram probability, and terms having the form P(c|a, b) correspond to a tri-gram probability.
2. The method of claim 1 , wherein the plurality of tokens each corresponds to a word of the first sentence.