8. The method of claim 7 , wherein tokenizing the at least one sequence of substrings into a set of token sequences comprises: removing known substrings having no semantic content in the domain to obtain a redacted at least one sequence of substrings; obtaining the set of token sequences from the at least one sequence of substrings by replacing each substring with a matching semantic token from the ontology; and replacing each substring having no matching semantic tokens from the ontology with a predefined unknown token.
8. The method of claim 7 , wherein tokenizing the at least one sequence of substrings into a set of token sequences comprises: removing known substrings having no semantic content in the domain to obtain a redacted at least one sequence of substrings; obtaining the set of token sequences from the at least one sequence of substrings by replacing each substring with a matching semantic token from the ontology; and replacing each substring having no matching semantic tokens from the ontology with a predefined unknown token. 10. The method of claim 8 , wherein obtaining one of the set of normalized relevance measures with respect to the domain corresponding to one token sequence of the set of token sequences comprises: obtaining a set of trigrams contained in the one token sequence; identifying entries in the trigram corpus of the domain matching each trigram in the set of trigrams contained in the one token sequence; obtaining a set of trigram probabilities in the trigram corpus corresponding to the identified trigram entries; determining a relevance measure of the one token sequence with respect to the domain based on the set of trigram probabilities; and normalizing the relevance measure of the one token sequence to obtain the one of the set of normalized relevance measures with respect to the domain for the one token sequence of the set of token sequences.