9. A computer system for determining a likelihood of a first and second document describing similar subject matter, the computer system comprising: a processor; and a memory; wherein the computer system is configured to: obtain a set of tokens for each of the first and second documents, wherein each set of tokens represents a series of characters found in its corresponding document; provide a matrix of token pairs, each token pair comprising a first token from the set of tokens corresponding to the first document and a second token from the set of tokens corresponding to the second document; generate a similarity score for each token pair in the matrix by: assigning each of the first token and the second token to one of a first type, a second type, or a third type based on the content of the tokens; setting the similarity score for the token pair to a floor value when the type of the first token is different from the type of the second token; setting the similarity score for the token pair based on a first calculation when the first token and the second token are of the first type; setting the similarity score for the token pair based on a second calculation different from the first calculation when the first token and the second token are of the second type; and setting the similarity score for the token pair based on a third calculation different from the first and second calculations when the first token and the second token are of the third type; identify those token pairs in the matrix with a similarity score above a threshold score and add the identified token pairs to a set of matched tokens; determine a similarity score for the first and second documents according to the scores of the token pairs in the set of matched tokens; and provide the determined similarity score as the likelihood of the first and second documents describing similar subject matter.
9. A computer system for determining a likelihood of a first and second document describing similar subject matter, the computer system comprising: a processor; and a memory; wherein the computer system is configured to: obtain a set of tokens for each of the first and second documents, wherein each set of tokens represents a series of characters found in its corresponding document; provide a matrix of token pairs, each token pair comprising a first token from the set of tokens corresponding to the first document and a second token from the set of tokens corresponding to the second document; generate a similarity score for each token pair in the matrix by: assigning each of the first token and the second token to one of a first type, a second type, or a third type based on the content of the tokens; setting the similarity score for the token pair to a floor value when the type of the first token is different from the type of the second token; setting the similarity score for the token pair based on a first calculation when the first token and the second token are of the first type; setting the similarity score for the token pair based on a second calculation different from the first calculation when the first token and the second token are of the second type; and setting the similarity score for the token pair based on a third calculation different from the first and second calculations when the first token and the second token are of the third type; identify those token pairs in the matrix with a similarity score above a threshold score and add the identified token pairs to a set of matched tokens; determine a similarity score for the first and second documents according to the scores of the token pairs in the set of matched tokens; and provide the determined similarity score as the likelihood of the first and second documents describing similar subject matter. 17. The computer system of claim 9 , wherein determining a similarity score for the first and second documents according to the scores of the token pairs in the set of matched tokens comprises dividing the sum of the similarity scores for of the token pairs in the set of matched token pairs by the sum of number of token pairs in the set of match tokens, the number of tokens from the first document less the number of token pairs in the set of matched tokens, and the number of tokens from the second document less the number of token pairs in the set of matched tokens.