Quote from: monsterer on February 08, 2016, 07:39:32 PM

Quote from: TPTB_need_war on February 08, 2016, 07:10:20 PM

Rather my upthread argument is that Byzantine fault tolerance requires the ability to distinguish between a fault and a non-fault, because otherwise the system does not present the same symptoms to all observers (which is a requirement of Byzantine fault tolerance). Satoshi's PoW can't distinguish a fault (attack) from a non-fault (non-attack).

Byzantine agreement is the process of forming a consensus decision on truth in the face of faulty network participants; bitcoin achieves this. Your definition of fault is incorrect in this context; a fault is information which the majority doesn't accept as truth, which manifest themselves as orphaned branches in bitcoin. Obviously all observers of the network can see orphaned branches.

Please respect canonical definitions. Byzantine 'agreement' is not what we are talking about in this thread. We are talking about Byzantine fault tolerance. The definitions are on Wikipedia:

Quote from: TPTB_need_war on February 07, 2016, 09:47:53 PM

A system which doesn't objectively (from the perspective of all observers) know when it is failing is not Byzantine fault tolerant.

Refer again to the Wikipedia definitions:

Quote from: TPTB_need_war on February 07, 2016, 06:44:52 PM

Quote from: https://en.wikipedia.org/wiki/Byzantine_fault_tolerance

The following practical, concise definitions are helpful in understanding Byzantine fault tolerance:[3][4]

Byzantine fault
Any fault presenting different symptoms to different observers
Byzantine failure
The loss of a system service due to a Byzantine fault in systems that require consensus

This circular logic of yours is getting redundant.

A fault is clearly defined above as any inability for all observers to be mutual objective about all symptoms. I already explained that censoring transactions or double-spends can occur where some observer is harmed but other observers can't be objective about whom has been harmed or whether the harm is really taking place or which hashrate to blame the fault on.

smooth's retort is such a fault doesn't occur until a % of the network is faulty (and he swears "I didn't inhale" but he did swallow and "that woman was never under my desk" but she was on top[1]), but again we can't measure nor prove when the network is faulty. If one says "yeah it is fault tolerant but I can't ever know when it is fault tolerant" that is not telling us any state where we know that observers are observing the same symptoms. The state can never be known. It is akin to arguing that yeah if the sealed box contains X then Y, but the box can never be opened.

Thus per the definition, Satoshi's PoW design is not Byzantine fault tolerant, because the metric of when it is fault tolerant is ill defined (can't be measured). An unknowable state is as reliable (fault tolerant) and a random result, thus no reliability exists.

smooth and r0ach said that Satoshi's PoW may still have value even without being strictly Byzantine fault tolerant. I pointed out it economically must become an oligarchy and asked what advantages are those? (note I have argued the advantage of Bitcoin is it drives R&D in crypto)

[1]

Quote from: Bill Clinton

It depends on what the meaning of the word 'is' is. If theif heif 'is' means is and never has been, that is notthat is one thing. If it means there is none, that was a completely true statement. Now, if someone had asked me on that day, are you having any kind of sexual relations with Ms. Lewinsky, that is, asked me a question in the present tense, I would have said no. And it would have been completely true.