Re: Third wheel
"Recording the correction of a mistake "
That's something easily done by a traditional database. The main "selling point" of blockchain is exactly that it cannot be manipulated by a single actor or small group of actors, everyone has to agree to the change. In a well-implemented blockchain you wouldn't try and correct something already done, because everyone on the blockchain has to agree and that ain't gonna happen. You reverse the original transaction, create the correct transaction anew, and swallow the transaction charges as the cost for having an error. This way only the 2 parties to the transaction have to agree to the reversals.