indefinite article before a possessives

[birdeen's call]

Possesives are determiners and a noun can take only one determiner. Therefore

The Tom's car is red.

is incorrect unless it's an unlikely case a specific Tom we want to talk about.

It has always been a difficult rule for me to abide by. I recently wrote

"Thick as a Brick" is also the title of Jethro Tull's prog masterpiece.

After posting it, I went out and couldn't remember if I didn't write "a Jethro Tull's prog masterpiece". The problem is that it doesn't sound wrong to me and I was sure I could have written it. Actually, it sounds better to me. In my mind, it's "one of the masterpieces by Jethro Tull". Or, again violating the rule, "one of the (Jethro Tull's masterpieces)". I see "Jethro Tull's" as an adjective here. If there was an adjective like "jethrotullian", all of these phrases would be correct after substituting "jethrotullian" for "Jethro Tull's".

I could try to believe that it's just my stubborn Polish brain refusing to accept reality. But it's impossible when I think of the phrase "a children's book". Clearly, this is exactly a possessive used like a regular adjective. "A" doesn't (what's the word, determine?) "children", but "children's book".

Could you please explain to me when exactly is it possible use possessives this way. I know "children's book" is a fixed phrase. But it must have been conceived by a native mind so maybe it's not impossible in other cases?

[5jj]

A children's book is a book for children, not a book belonging to children, though there is nothing wrong with the children's book, and we can have John's children's book.

John's children's books are in the chest in the attic.

This could mean either his juvenile books or the books of John's children; context will make that clear.

We can't have the John's book.

[Raymott]

Possesives are determiners and a noun can take only one determiner. Therefore

The Tom's car is red.

is incorrect unless it's an unlikely case a specific Tom we want to talk about.

It has always been a difficult rule for me to abide by. I recently wrote

After posting it, I went out and couldn't remember if I didn't write "a Jethro Tull's prog masterpiece". The problem is that it doesn't sound wrong to me and I was sure I could have written it. Actually, it sounds better to me. In my mind, it's "one of the masterpieces by Jethro Tull". Or, again violating the rule, "one of the (Jethro Tull's masterpieces)". I see "Jethro Tull's" as an adjective here. If there was an adjective like "jethrotullian", all of these phrases would be correct after substituting "jethrotullian" for "Jethro Tull's".

You're talking about "a Jethro Tull masterpiece". You're right - you cannot have "a Jethro Tull's masterpiece." It's a masterpiece of Jethro Tull. (I don't know what 'prog' means, so I haven't used it).

You can say:
"The Choral Symphony is Beethoven's masterpiece." (ie. his major work).
"The Choral Symphony is a Beethoven masterpiece." (ie. one of his major works).
You cannot say:
"The Choral Symphony is a Beethoven's masterpiece." (unless you're being clever, and implying that there are more than one Beethoven being talked about, and the Choral Symphony is a masterpiece of one of these Beethovens.)

[birdeen's call]

A children's book is a book for children, not a book belonging to children, though there is nothing wrong with the children's book, and we can have John's children's book.

John's children's books are in the chest in the attic.

This could mean either his juvenile books or the books of John's children; context will make that clear.

We can't have the John's book.

Yes, I know we can't. And this does sound wrong to me. I must say I'm having trouble understanding where my problem lies.

What do you think about my Jethro Tull examples? Do they strike you as incorrect? Are they possible utterances in native speech?

Are there any more examples of phrases like "a children's book"?

[birdeen's call]

You're talking about "a Jethro Tull masterpiece". You're right - you cannot have "a Jethro Tull's masterpiece." It's a masterpiece of Jethro Tull. (I don't know what 'prog' means, so I haven't used it).

You can say:
"The Choral Symphony is Beethoven's masterpiece." (ie. his major work).
"The Choral Symphony is a Beethoven masterpiece." (ie. one of his major works).
You cannot say:
"The Choral Symphony is a Beethoven's masterpiece." (unless you're being clever, and implying that there are more than one Beethoven being talked about, and the Choral Symphony is a masterpiece of one of these Beethovens.)

Thank you. I understand.

("Prog" means progressive rock.)

[5jj]

What do you think about my Jethro Tull examples? Do they strike you as incorrect? Are they possible utterances in native speech?
I think Raymott has answered that.

Are there any more examples of phrases like "a children's book"?
A Student's/Teacher's book, a Town Marshal('s) badge, a miner's lamp, a nurse's uniform, ...

5

ps, later: I meant to emphasis 'think' in my first sentence.

[birdeen's call]

Thank you very much. This was very helpful. (Even if not very pleasing. I really hate it when my intuitions are wrong.)