Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Model Checking and Synthesis for Optimal Use of Knowledge in Consensus Protocols

Kaya Alpturer, Gerald Huang, Ron van der Meyden

TL;DR

This work applies epistemic model checking with MCK to analyze Simultaneous and Eventual Byzantine Agreement under practical, limited information-exchange models, aiming to identify opportunities for earlier decisions and to synthesize optimal protocols. It formalizes SBA and EBA specifications, leverages knowledge-based programs, and demonstrates automatic synthesis of implementations relative to chosen information exchanges and failure models. Through modeling variants of information exchange (FloodSet, counting crashes, memory of count, and Dwork–Moses) and error models (crash and omissions), the study reveals when common knowledge enables earlier termination and how synthesis scales. The results show feasibility for small-scale instances and provide benchmarks and insights for improving epistemic model checking and synthesis, while acknowledging significant scalability limitations and suggesting avenues for future parametric and algorithmic improvements.

Abstract

Logics of knowledge and knowledge-based programs provide a way to give abstract descriptions of solutions to problems in fault-tolerant distributed computing, and have been used to derive optimal protocols for these problems with respect to a variety of failure models. Generally, these results have involved complex pencil and paper analyses with respect to the theoretical "full-information protocol" model of information exchange between network nodes. It is equally of interest to be able to establish the optimality of protocols using weaker, but more practical, models of information exchange, or else identify opportunities to improve their performance. Over the last 20 years, automated verification and synthesis tools for the logic of knowledge have been developed, such as the model checker MCK, that can be applied to this problem. This paper concerns the application of MCK to automated analyses of this kind. A number of information-exchange models are considered, for Simultaneous and Eventual variants of Byzantine Agreement under a range of failure types. MCK is used to automatically analyze these models. The results demonstrate that it is possible to automatically identify optimization opportunities, and to automatically synthesize optimal protocols. The paper provides performance measurements for the automated analysis, establishing a benchmark for epistemic model checking and synthesis tools.

Model Checking and Synthesis for Optimal Use of Knowledge in Consensus Protocols

TL;DR

This work applies epistemic model checking with MCK to analyze Simultaneous and Eventual Byzantine Agreement under practical, limited information-exchange models, aiming to identify opportunities for earlier decisions and to synthesize optimal protocols. It formalizes SBA and EBA specifications, leverages knowledge-based programs, and demonstrates automatic synthesis of implementations relative to chosen information exchanges and failure models. Through modeling variants of information exchange (FloodSet, counting crashes, memory of count, and Dwork–Moses) and error models (crash and omissions), the study reveals when common knowledge enables earlier termination and how synthesis scales. The results show feasibility for small-scale instances and provide benchmarks and insights for improving epistemic model checking and synthesis, while acknowledging significant scalability limitations and suggesting avenues for future parametric and algorithmic improvements.

Abstract

Logics of knowledge and knowledge-based programs provide a way to give abstract descriptions of solutions to problems in fault-tolerant distributed computing, and have been used to derive optimal protocols for these problems with respect to a variety of failure models. Generally, these results have involved complex pencil and paper analyses with respect to the theoretical "full-information protocol" model of information exchange between network nodes. It is equally of interest to be able to establish the optimality of protocols using weaker, but more practical, models of information exchange, or else identify opportunities to improve their performance. Over the last 20 years, automated verification and synthesis tools for the logic of knowledge have been developed, such as the model checker MCK, that can be applied to this problem. This paper concerns the application of MCK to automated analyses of this kind. A number of information-exchange models are considered, for Simultaneous and Eventual variants of Byzantine Agreement under a range of failure types. MCK is used to automatically analyze these models. The results demonstrate that it is possible to automatically identify optimization opportunities, and to automatically synthesize optimal protocols. The paper provides performance measurements for the automated analysis, establishing a benchmark for epistemic model checking and synthesis tools.
Paper Structure (21 sections, 1 theorem, 3 equations, 3 tables, 1 algorithm)

This paper contains 21 sections, 1 theorem, 3 equations, 3 tables, 1 algorithm.

Table of Contents

  1. Introduction
  2. Semantic Model
  3. Communication and Failure Models
  4. Specifications
  5. Knowledge-Based Program - Simultaneous Byzantine Agreement
  6. The Model Checker MCK
  7. Information Exchange Protocols for SBA
  8. FloodSet Protocol
  9. Counting the number of crashed agents
  10. Diff: Memory of Count
  11. Dwork-Moses
  12. Knowledge Based Program - Eventual Byzantine Agreement
  13. Information Exchanges for Eventual Byzantine Agreement
  14. Information Exchange $\mathcal{E}^{min}$
  15. Information Exchange $\mathcal{E}^{basic}$
  16. ...and 6 more sections

Key Result

proposition 1

Let $\mathcal{E}$ be an information exchange protocol and let $\mathcal{F}$ be failure model, and let protocol $P$ be an implementation of $\mathbf{P}$ relative to $\mathcal{E}$ and $\mathcal{F}$.

Theorems & Definitions (1)

  • proposition 1