(13) Lexical entries in basic structures must have the thematic roles of their arguments associated with their grammatical functions withouth crossing links between the tiers of Figure 2, and with exactly one thematic role linked to SUBJ. Predicates that respect the no-crossing-links provision of (13) may be called "canonical"; those that violate it are "noncanonical". [...] a learning procedure for canonical mapping [...] can be called L2: namely, create a lexical entry for a predicate by assigning grammatical functions to its thematic roles in such a way that (13) is respected.
- Pinker (2004), a pag.247