2. Challenges for decentralized electronic money creation How to remove the need of central organization and trust to one party? How to ensure honest voting process in anonymous, trustless, decentralized system? How to prevent double-spending? How to encourage users to join the system?
6. Step 3. Verification of the incoming cheque Everybody can verify unique identifier in their own copy of the database (blockchain).
8. Most important questions How many participants have to vote to accept or reject particular transaction? How can you define “participant”? Is it a person or a piece of code? How many participants take part in the voting process? Do they know and trust each other? Probably not. How to ensure honest voting process in such conditions?
10. How does “hard task” should look like? Everybody has a chance to win It should be able to prevent fraud Everybody can verify results The result of one participant cannot be stolen by another It should encourage participants to work more The closest analogue of such a task is participation in the lottery – everybody has a chance to win, but those who buy more will more likely win.
11. Mining in Bitcoin it is just a process of permanent checking answers for certain mathematical equation. It is not connected to transaction verification – it is just needed to prevent votes “buying”.