Speaker: Andrea Rizzini
September 14th, 2026 | 10:00 am
DEIB, BIO1 Room (Bld. 21)
Contact: phd-inf@polimi.it
Abstract
On September 14th, 2026, at 10:00 am Andrea Rizzini, PHD Student in Information Technology, will give a seminar on "Deterministic limits and randomized consensus: the road to Algorand" in DEIB, BIO1 Room (Building 21).Byzantine agreement is the backbone of every replicated system. Starting from the consensus problem and the standard modelling choices, this talk revisits the Dolev-Strong protocol, which achieves Byzantine broadcast with optimal resilience assuming a public-key infrastructure, at the price of a number of rounds that grows with the number of faults and a quadratic amount of signed traffic. Both bounds are known to be optimal for deterministic protocols, so scaling to large networks requires changing the assumptions rather than sharpening the analysis. We then follow the randomized route: committees sampled afresh in every round through an unbiasable cryptographic lottery, honest-majority guarantees obtained from concentration bounds, and the resulting communication cost that grows only linearly in the number of parties, leading to Algorand BFT.