Different Perspectives on FLP Impossibility

TL;DR

This paper challenges the traditional FLP impossibility result by introducing a new paradigm that separates termination from agreement, and presents an algorithm ensuring termination with initial input agreement.

Contribution

It introduces a novel paradigm for consensus termination and provides an algorithm that guarantees termination with agreement on initial inputs under asynchronous conditions.

Findings

Demonstrates that termination is possible even when agreement is impossible.

Introduces a new paradigm separating termination from agreement.

Provides an algorithm ensuring termination with initial input agreement.

Abstract

We demonstrate termination of binary consensus under the model and conditions used by Fischer, Lynch, and Patterson (FLP) to prove impossibility of binary agreement - in complete asynchrony and a possible process crash - in two steps. First, we introduce a new paradigm for consensus termination and show that impossibility of agreement is not evidence for impossibility to terminate. Next, we present a consensus algorithm that ensures termination with agreement about the initial input from the processes.