Mutation and constituent structure in Welsh

Like the other Celtic languages, Welsh has systems of word-initial consonant alternations known as mutations. Typically, mutation is triggered by an immediately preceding lexical item of some kind. However, Harlow (1989) pointed out that there are examples where mutation seems to be triggered by an immediately preceding NP. Borsley and Tallerman (1998) argue that mutation is in fact triggered by any immediately preceding and c-commanding phrase. This proposal seems a promising one, but it faces a number of problems. Some of the problems are associated with assumptions specific to the Principles and Parameters (P&P) framework, but others look like problems for any theoretical framework. It seems, however, that a version of the Head-driven Phrase Structure Grammar (HPSG) framework can provide a simple account of the facts in which the various problems disappear. More generally, it seems that whereas P&P assumptions about syntactic structure are quite problematic in this area, HPSG provides just the right sort of syntactic structure to give a satisfactory account of the process. (C) 1999 Elsevier Science B.V. All rights reserved.