Common knowledge revisited

TL;DR

This paper revisits the common-knowledge paradox, exploring how coarse modeling and relaxed coordination requirements can address the challenge of achieving common knowledge in real-world scenarios.

Contribution

It analyzes the paradox and proposes two solutions: coarser world modeling and relaxed coordination, to reconcile the necessity and unattainability of common knowledge.

Findings

Coarser modeling can mitigate the paradox.

Relaxing coordination requirements offers practical solutions.

The paradox remains a fundamental challenge in distributed systems.

Abstract

We consider the common-knowledge paradox raised by Halpern and Moses: common knowledge is necessary for agreement and coordination, but common knowledge is unattainable in the real world because of temporal imprecision. We discuss two solutions to this paradox: (1) modeling the world with a coarser granularity, and (2) relaxing the requirements for coordination.