Use of possessive determiners with adjectives

Question

I've read this thread and while it does seem to give me the answer I am looking for, I still wanted to ask a related question.

Let's take the following sentences as examples:

"He lives in a flat, and she lives in his same flat."

"He lives in a flat, and she lives in his flat."

"He lives in a flat, and she lives in the same flat."

Considering the aforementioned thread, it should be fine to have an adjective come after a possessive determiner ("same" coming after "his"), however this kind of sentence doesn't sound right to me. Sentences 2 and 3 do seem like grammatically correct alternatives, though I can't figure out why they are correct whilst the 1st sentence is not.

Could anyone tell me if this kind of structure (sentence 1) is fine or not, and explain why it is/isn't so?

Answer 1

Adjectives usually fulfil one of three roles.

Adjectives being used as identifiers are adjectives being used to pick out a particular referent in a given context (Pass me the red book, would you, please?)

Adjectives being used as classifiers are adjectives being used to identify a whole general subset (Electric lighting is the norm nowadays).

Adjectives being used as descriptors are adjectives being used to add general information about the referent's attributes (The cloudless sky was beautiful and clear), rather than to single out an element or subset.

[see Polysemy: Flexible Patterns of Meaning in Mind and Language ... edited by Brigitte Nerlich, Zazie Todd, Vimala Herman]

Obviously, a given adjective isn't restricted to one role. Less obviously, the role an adjective is playing in a given sentence may be difficult to judge.

The identifier role of an adjective is very similar to the role of some determiner types (demonstrative and possessive) and one might expect that grammatical behaviour might reflect this to a certain degree. Though 'his new flat' is fine ('new' may be an identifier or descriptor here), 'his same flat' sounds almost as bad as 'his those flats'. 'Same' and 'different' are actually classified in a group known as 'adjectives of selection' [see Coppock: The Predicativity Principle, slide 31]. So is 'exact'; 'his exact answer' sounds idiomatic, while, I'd say, 'his exact flat' doesn't.

As usual, what seemed a nice concise answer turns out to be a rule-of-thumb, with exceptions.