In this way, the hypertagger makes high-level microplanning decisions and the grammar and the lexicon further refine those decisions by enforcing hard constraints such as the possible subcategorization pattern of a given literal (encoded in the lexicon)-for example, sDOTnx0VVVpnx1-or the choice (encoded in the grammar trees) between a comma-conjoined relative clause (COMMAW0nx0VVVpnx1) and a relative clause introduced by and (ANDW0nx0VVVpnx1).
we use the hypertagger to rank the syntactic construct sequences in terms of naturalness while the grammar and the lexicon are used to enforce hard lexical and grammatical constraints such as the fact that a comma-separated clause must be followed by a clause introduced by a coordination word (e.g., and or or).