[Grammar] That's an old guitar of Tommy's.

[kadioguy]

Hi, members.

This is a simpler thread of this.

You may be on the right track, but I don't think it's a hard and fast rule. She's an old girlfriend of mine definitely works. That's an old guitar of mine would not, I think, raise eyebrows. It's an old house of mine is more of a stretch.

Replace "mine" with Tommy's and only the "girlfriend" sentence works.

I don't know why the following two don't work.

(a) That's an old guitar of Tommy's.
(b) It's an old house of Tommy's.

But (c) works.

(c) Can't you throw out that old bike of Tommy's?

Could you tell me?

 

[kadioguy]

You have already asked this question here: https://www.usingenglish.com/forum/threads/280277-the-property-of-the-residents

Yes, but I am afraid that that thread is mixed up, so I started up a simpler one here.

Please see the last part of the last post there.

(Update)

I think that this thread is still a little mixed up, so I'll start up a simpler one.

 

[kadioguy]

Life will get even more mixed up if some people respond in the other thread and others respond here.

Thank you for the reply.
That wouldn't be my wish. I'll close that one.

 

[jutfrank]

I don't know why the following two don't work.

(a) That's an old guitar of Tommy's.
(b) It's an old house of Tommy's.

But (c) works.

(c) Can't you throw out that old bike of Tommy's?

Could you tell me?

I think they're all okay. They follow my rule by using a possessive 's after a person's name.

I'll add something to my rule that I think is something of an exception:

With: a friend of + person, it sounds okay if you don't use the apostrophe 's. I think this is a special case.