On clashes and lapses

In phonology, one of the generalisations that seems to hold true across most, if not all, languages is that the overall rhythmic pattern tends to be organised such that there is an alternation of strong and weak syllables (cf. among others, Hayes 1980, 1984; Prince 1983; Selkirk 1984). In other words, languages tend to avoid strings of adjacent strong syllables, as well as strings of adjacent weak syllables. These generalisations are expressed by clauses (a) and (b), respectively, of Selkirk's Principle of Rhythmic Alternation (PRA): (1) Principle of Rhythmic Alternation (Selkirk 1984: 52) a. Every strong position on a metrical level n should be followed by at least one weak position on that level b. Any weak position on a metrical level n may be preceded by at most one weak position on that level Of course, the underlying rhythmic patterns of a language are not always in conformity with the PRA.