The application of lexical rules is a third way in which the child could acquire lexical entries. Naturally, this begs the question of how lexical rules themselves are learned. Here is a mechanism proposed in Pinker [Pinker, Steven, 1982, A theory of the acquisition of lexical interpretive grammars, in Bresnan, J., ed., "The mental representation of grammatical relations, MIT Press, Cambridge], which I will call L3: L3. If a predicate has two lexical entries each with the same number and type of arguments but with different grammatical functions encoding these arguments, coin a lexical rule that specifies the replacement of each function in the first lexical entry by its counterpart in the second. The lexical rule also should add or delete any feature equations that distinguish the two entries.
- Pinker (2004), a pag.250