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.
9. The method of claim 8 , wherein each token sequence of the set of token sequences is further preceded with two symbolic start tokens and appended with one symbolic end token.