This makes the syntactic structures simpler. Together with the fact that Lexicase is a very constrained theory even when compared to other DGs, this provides evidence for our general approach. Simple and accurate measure of syntactic difficulty Richard Hudson proposed a measure of syntactic difficulty based on the number of words occuring between a dependent and its governor, called dependency distance . In general, words also have properties, which might contain one attribute, e.g. the word class, encoding the distribution. Maybe Radford was saying that there must be distinction between the word class, which is a lexical property, and the distribution of the phrase headed by the word, which is also influenced by other words in the phrase.
Phrasal categories are necessary to describe recursion.
Clearly, a word of class X may govern other words of class X, giving you recursion without phrasal categories. State University of New York Press. Recent Trends in Dependency Syntax. Lobin et al. Japanische Morphosyntax .