Hi Shunsai:

1.According to my understanding, the approvals stored in each block-approval-block are the approvals for the current block. So where are the conflicted approvals stored? If they are not stored in the history blocks, how could you tell a stackholder approves conflicted blocks. In other words, according to what should you punish the double-approving behavior to prevent "nothing at stake" problem?

2. About the instant finality. If you determine the realchain so quickly, how could you prevent the blockchain from spliting into different forks for ever when there happens something that separate the network temporaryly, like intercontinental optical fiber cable fracture?  

3. About the history attacks. Why don't you just mention that the protocol has instant finality? Because that resolved all the history attacks if it works.