Nouns as modifiers

[Jase]

When a noun is used to modify another noun, how is it represented in X-bar Theory? It’s funny that Carnie has not yet explained this (or I missed it), and yet he gave us several exercises with it in the GPS sections of chapter 7.

For example, see number GPS5(b): Linguistics students like phonetics tutorials. If linguistics and phonetics were adjectives, we would go [NP [N'...[AdjP...[N...]]], but that isn’t the case.

I’ve attached a tree image with my question more specifically worded. Thanks!

[Jase]

I accidentally used D' instead of D in the image. Please, ignore that.

[Daniel]

This is a good essay I've seen assigned in classes that use his book

Either analysis is possible-- you could say that it's possible to modify a noun with a noun (and add the appropriate PSRs), or you could say that in those instances the N becomes an A and use the normal AP rule.

The distinction, which you can work out yourself if you'd like, depends on distributional criteria.

Consider, for example:
*The very water fountain.
The very large fountain.
*The linguistics student is better than the physics one.
The nice student is better than the mean one.