nltk.PCFG.is_nonlexical¶

PCFG.is_nonlexical()¶

Return True if all lexical rules are “preterminals”, that is, unary rules which can be separated in a preprocessing step.

This means that all productions are of the forms A -> B1 ... Bn (n>=0), or A -> “s”.

Note: is_lexical() and is_nonlexical() are not opposites. There are grammars which are neither, and grammars which are both.