I have to agree with franky1, c'mon, not sure who your trying to fool, if you have made about 200+ posts here you probably can answer these questions just by having read them at some-point when it was asked by others or you through personal research find the answers.
You have been involved with this forum for nearly 4 years and have not found the answer to your extraordinarily vague questions. Based on your question and post count, people will assume you have purchased this legendary user account.
Ok, so I'm a noob who purchased this account. Now, what is the answer?
Franky1 largely answered this but I can take a crack real quick:
What is the minimal set of assumptions that must be correct for Bitcoin to function properly?
- Electricity, Internet, Two computers which are networked together running compatible Bitcoin Clients.
For example, we assume that it's possible to distinguish work done during mining of bitcoins VS work done during mining of other coins. If we wasn't able to identify blockchain belonging to Bitcoin then any coin with higher cumulative difficulty would "overwrite" work/electricity burned for Bitcoin.
- Since every single block in the chain includes a hash of the entire previous blocks data, this would be fine with your assumptions, for the user to "overwrite" they will actually have to be using the exact same blockchain as everyone else to with the exact same data previously hashed as everyone else in the world. Otherwise they will be adding blocks to their alternative blockchain that no network participants will recognize as the real chain because the alternative chain would never be able to grow longer than the real blockchain read section 11:
https://bitcoin.org/bitcoin.pdfThe attackers chain would always be behind, unless they held a significant portion of the network like pointed out by others previously.