In a book(Wren and Martin updated Indian edition) I am reading it is said:
The forms my, our, your, her, their are called Possessive Adjectives because they are used with nouns and do the work of Adjectives; as,
This is my book.
Those are your books.
That is her book.
My understanding is that my, your and her can be replaced with adjectives in the above sentences as:
This is the red book.
These are better books.
That is a small book.
In the book I am reading, it further says mine, yours, hers are possessive pronouns, as used in following sense:
This book is mine.
These books are yours.
That book is hers.
That idea of yours is excellent.
But my question is that mine, yours, hers are infact taking the position of Predecative adjectives as:
This book is red
These books are better
This book is small
So, can mine, yours, hers be considered as Possessive adjectives? If not then why?