[esotericn]

Ah, I see the issue. It's the timestamping problem.

You have no way of detecting whether a user "bought a ticket" on seeing the inspector or not.

[lixtra]

You can do statistical analysis if certain users get checked unusually often (I.e. generate tickets only when checked). After some time you can force those users into online only mode.

[lonelappde]

That doesn't work because ticket checks are far too rate to develop a statistical model for any one user.

[esotericn]

You have no way of knowing that they generate tickets only when checked.

[dwild]

I have nearly no information about this scheme because the post got removed.

It has to be partially online, how do you pay without an online connection? Is there some kind of amount you have and then you can redeem them offline?

At one point you do require an online check in, that's for sure, that's when you find out whether the tickets were bought only when checked or not.