One of the fundamental problems of distributed computing that tolerates errors is the problem of the Byzantine agreement. The Byzantine agreement requires a group of parties to agree on a value in a dispersed environment, even if some of the parties are corrupt. The aim is to automate the analysis of the ABBA protocol using the methodology established in our previous paper [KNS01a] on the basis of [MQS00]. In [KNS01a], we used Cadence SMV and probabilistic model tester PRISM to test the simpler randomised MOU for Aspnes and Herlihy [AH90] which only tolerates benign shutdown errors. We achieved this through a combination of mechanical inductive proofs (for all n for non-probabilistic properties) and tests (on finished configurations with probabilistic properties) and high-quality manual proof. However, the ABBA protocol revealed a number of difficulties that were not encountered earlier: it should be stressed that we cannot automate the last inductive argument, as it is likely that the SMV cadence cannot handle likely probability, while PRISM can only deal with finite configurations and does not support data reduction. Instead, we validate the probabilistic analysis as follows. By observing that the problem can be reduced for a modeling test of a finite state analysis of the protocol, we manually construct an abstraction and model test with PRISM, which allows to validate the probabilities for No. 20 parts. In addition, we check (for a finite configuration) the accuracy of the abstraction with the CSP process algae [Ros97] and the method-based FDR tool in [KNS01a]; it depends on the ability to code probabilities in action names and therefore excludes the use of Cadence SMV.

A randomized protocol uses random attribution, z.B. electronic stoltosing, and its termination is therefore likely. The terms of a randomized contract are: We consider the randomized Byzantine Memorandum of Understanding ABBA (Asynchronous Binary Byzantine Agreement) of Cachin, Kursawe and Shoup [CKS00], which is placed in a completely asynchronous environment that allows the maximum number of corrupted parts and uses cryptography and randomization. There are n parties, an opponent who cannot corrupt as many of them as much as possible (t < n/3) and a trusted dealer.