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For some reason I thought that the Byzantine Generals problem was all about coordinated action and TCP handshakes and stuff. I.e. two Byzantine generals are bes
by OskarS 10y ago
For some reason I thought that the Byzantine Generals problem was all about coordinated action and TCP handshakes and stuff. I.e. two Byzantine generals are besieging a city from opposite sides. In order to successfully invade it, they have to attack at the same time. General A sends a messenger to General B saying "attack tomorrow at 1 PM". But the messenger might be captured, so General A wants to be sure that General B got the message, because if General A attacks alone he's doomed.
So General B sends a messenger back saying "i got the message!". But now General B is unsure that General A got the return messenger. If the return messenger was captured, General A will think that General B didn't get the original message and will not attack, so if General B attacks, he's doing it alone. General B thus needs to know that General A got the return message. So General A sends a return-return messenger. And General B sends a return-return-return messenger. And on and on and on.
- jobigoud 10y agoThat's the Two Generals problem which is a special case of the Byzantine Generals problem.
- erikb 10y agoCould you explain further, e.g., why this is a subset of the general Byzantine Generals problem and what the BG problem is exactly? Because both descriptions don't really match the same problem set, as far as I see.
- jobigoud 10y agoFrom Lamport's paper: > two generals have to come to a common agreement on whether to attack or retreat, but can communicate only by sending messengers who might never arrive. I stole the idea of the generals and posed the problem in terms of a group of generals, some of whom may be traitors, who have to reach a common decision.