Hello Paul,
"Proof of approval is an approximation of a PoS chain in which every block is signed by all the stake in the system"?
How about this?
Proof-of-Approval is a stake based protocol where every block is signed by the stake majority and every epoch is signed by almost the entire stake in the system.
Regards,
Shunsai
The ultimate goal, though, is to have the entire stake in the system sign every block, isn't it? I know that would be totally unfeasible because of the size of the data, but this is the security model you're aiming to approximate?