I learned that you use "for -ing" and not a 'to' infinitive when you want to say the purpose of a tool, but I am not so sure about it.
People told me I should say:
This computer is for you to attend lectures. (1a)
This computer is for attending lectures. (1b)
This computer is to attend lectures. (1c)
However, can't a 'to' infinitive alone be used as an adjective to indicate the purpose? For example, can't I say:
You have a computer to attend class. (2a)
You have a computer for you to attend class. (2b)
If I can, what do you think makes such a difference between the 1s and 2s?