[cap-talk] impossibility of solving the "coordinated
attack problem" ("generals problem")
Jed at Webstart
donnelley1 at webstart.com
Thu Feb 2 18:52:02 EST 2006
At 02:36 PM 2/2/2006, Valerio Bellizzomi wrote:
>On 02/02/2006, at 14.14, Jed at Webstart wrote:
>...What it really means is
> >that it is NEVER possible to come to agreement, to do the
> >"coordination" and to have both entities agree. I think perhaps
> >an algorithmic approach is the best way to clarify the fundamental
> >problem. You really have to put yourself in the position of the
> >boss or the lieutenant. Let's try laying out possible algorithms:
>At some point someone makes a decision of trust: he trusts that the
>messenger will arrive, and so he executes the action anyway.
I don't think there is an "alternatively".
>if the communication is simultaneous in both directions,
It is, or at least it can be, of course, but the decision is made on
one side only.
>it just takes one round-trip in both directions.
To do what? Not come to agreement/coordination.
>In this case it is a question
>of timing. If one messenger arrives out of time, the algorithm must
I don't understand what you're getting at above. In any case
the last one to send a message is in an ambiguous situation
and can't be confident/sure that the attack is "coordinated".
That last message might not arrive. There is no way out
of this "paradox"/problem.
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