Possessive pronoun and definite article

Question

I wanted to ask a question about the possessive pronouns in Spanish.

I was learning about possessive pronouns e.g. el mío and I was given the following sentence:

No me gusta este bolso rojo, prefiero el suyo.

However, when reading texts online, I would often find the definite article being dropped e.g.:

El auto azul es mío.

I was wondering whether the definite article being removed is just to simplify the sentence during speech and written form, or whether the definite article should actually not be included in the sentence at all (as I have learnt).

My question is, which sentence is therefore correct (or are both correct):

No me gusta este bolso rojo, prefiero el suyo.

or

No me gusta este bolso rojo, prefiero suyo.

Answer 1

The forms:

• mío/a/s
• tuyo/a/s
• suyo/a/s

can be used with an article as follows:

1- Un bolso mío es rojo. (A bag of mine is red)

2- El bolso mío es rojo. (The bag that is mine is red) (This is more emphatic than "Mi bolso es rojo")

3- Ese bolso rojo es el mío. (That bag over there is the one that belongs to me)

Without an article, the mentioned possessives can only be used in the predicate with the verb "ser":

4- Ese bolso rojo es mío. (That bag is mine)

As regards the final question:

• No me gusta este bolso rojo, prefiero el suyo. IS CORRECT (I prefer yours)

but

• No me gusta este bolso rojo, prefiero suyo. IS NOT because, as explained under (4), such possessives can only be used predicatively without an article with copulative verbs "ser" or "parecer" to mean "belong to sb" (or "seem to belong to sb").