They are in one of the cases pointed out, not the other two. The novel idea is to have two networks compete against each other in a two-player minimax game, dev

They are in one of the cases pointed out, not the other two. The novel idea is to have two networks compete against each other in a two-player minimax game, developing progressively better strategies until something like Nash equilibrium is reached--at which point you have one well-trained classifying network and one well-trained generating network.