adjective pronominalization with の

Question

大きいのはいくらですか。　

きれいなのを買いました。

I found those phrases here. From my understanding these mean:

大きいの = the ones that are big

きれいなの = the one that is pretty | the ones that are pretty

Am I right? I didn't manage to find any explanation online and on my grammar book. Is it correct to use the same construction with other tenses, like 大きくないの (= the one that is not big) or きれいだったの (= the one that was pretty)?

Answer 1

Your interpretation is correct.

In these 2 sentences, the objects that the adjectives refer to were omitted. They are probably mentioned before these phrases. If an adjectival phrase refers to something that is already known, the object can be referred to by の.

And yes, it can be used with other tenses too. The usage is exactly the same.