Round duration / Fast appeal

[irenegia]

Each appeal is processed ("the trial") in rounds. Each round has a fixed duration (round_duration), this is a protocol parameter. Right now we have round_duration = 300 s (5 min). Is this a good values?

Average block time at the time of the issue: ~12s https://ycharts.com/indicators/ethereum_average_block_time#:~:text=Ethereum%20Average%20Block%20Time%20is,10.93%25%20from%20one%20year%20ago.

[irenegia]

Requirements that I know:

• it can not be too short (not below 300s) otherwise no time for executing the round protocol
• we may want to make it longer so that the $k$ rounds cover the filecoin unsealing time (2h)
  • with $k = 12$, this means round_duration = 2h / 12 = 10 minutes
• it may depends on the blockchain on which we launch the alpha. Indeed in each round we need to have enough time to be sure that the message (the failure message) goes on chain (ie, round_duration larger than duration)

[irenegia]

idea: can we have different params in the same smart contract?

Add a field to the deal structure to mark it as "fast conflict resolution", in this case appeal rounds will be much shorter ( is 2 secs per round feasible?)

• note: fast retrieval looks more a TTFB than the entire download time.

[irenegia]

• likely not possible on FEVM/FVM because confirmation is 60s, see #97
• still make sense for arbitrum