### Ver Post

## Inesc - ID - Talk by Michel Raynal

13 Novembro 2014, 12:54 - Lucília Abreu

Appeared in PODC 2014**Abstract**

This talk presents a new round-based asynchronous consensus algorithm that copes with up to t<n/3 Byzantine processes, where n is the total number of processes. In addition of being signature-free and optimal with respect to the value of t, this algorithm has several noteworthy properties: the expected number of rounds to decide is four, each round is composed of two or three communication steps and involves $O(n²) messages, and a message is composed of a round number plus a single bit. To attain this goal, the consensus algorithm relies on a common coin as defined by Rabin, and a new extremely simple and powerful broadcast abstraction suited to binary values. The main target when designing this algorithm was to obtain a cheap and simple algorithm. This was motivated by the fact that, among the first-class properties, simplicity –albeit sometimes under-estimated or even ignored-- is a major one.**Bio **http://www.irisa.fr/prive/raynal/ **Keywords**: Abstraction, Asynchronous message-passing system, Broadcast abstraction, Byzantine process, Common coin, Consensus, Distributed algorithm, Optimal resilience, Randomized algorithm, Signature-free algorithm, Simplicity.

The information are available here http://www.inesc-id.pt/seminars.php