I've read various descriptions of the TGP, most of which seem vague or conflicting on the precise constraints of the problem. Specifically:
- is it always or sometimes impossible to reach consensus
- finite/infinite messages required
- given unreliable communication, is actual message loss important or not.
As another point, the depiction of the problem seems inadequate, as there's no need for the generals to always require acknowledgement for their last message if they regard previous ones:
0 A ----time info--> B
1 A <---AckForA0---- B
2 A ----AckforB0---> B
3 A <---AckforA1---- B
1... A knows B received his time info and is ok with it but might not attack if he doesn't receive confirmation for his ack.
2... B knows A received his ack because he responded.
3... A knows B got his ack because he responded
Can anyone give a better example which illustrates this specific need to rely on acks of the respective last messages.