Are determiners heads?

The paper focuses on the relation between the determiner (D) and the common noun (N) in a noun phrase (NP). Four facts show that D depends on N: only N is relevant to whether NP can be used as an adjunct; possessive determiners are similar to clearly dependent possessives e.g. in Dutch and German; N decides whether or not D is obligatory; and in English only one D is possible per N. Three other facts show the converse, that N depends on D: in many languages D sometimes fuses with a preceding preposition (e.g. French de le = du ; English for each = per ); D decides whether or not N is obligatory; the ellipsis of N is a regular example of dependent ellipsis. Therefore D and N are mutually dependent, a relation which requires the structural flexibility offered by Word Grammar. This does not mean that NP has two heads, but rather that either D or N may be the head.