In my another post (Using "far away" and "far from" when talking about the position of adverb) I said
Provided that post is to discuss the position of the adverb "carefully", similar to the guy A in previous example, is it grammatical and idiomatic to say in the following way?
where I use infinitive form of discuss.
Actually, I am not sure if I use the right form. Consider other 2 possibilities
that post is discussing ...
that post discusses ...
In this situation, which one should I use?
Is there some kind of rules for this?