We covered a lot of ground in this series. We started with the following objectives:

• Propose an alternate and more approachable definition of consensus.
• Expand the definition into concrete requirements.
• Break the problem down into goal-oriented rules.
• Provide algorithms and approaches to satisfy the rules with adequate explanations to prove correctness and safety.
• Show that existing algorithms are special cases of this generalization.

Below is a summary of the topics we covered.

This section covers topics that were deferred in the previous parts. However, these are necessary to deploy consensus systems in production.

This section discusses various approaches to achieving consistent reads in a consensus protocol.

This section discusses ways to change the durability rules for a consensus system. As you will see below, any approach that respects the governing rules is sufficient to safely effect these changes.

This section covers the second part of a leadership change: The discovery of the best timeline and its propagation to prepare for the next leadership.

This section covers ways to satisfy the prerequisites for a leader change: Revoke previous leaderships and recruit nodes for the new leader candidate.

In this section we will discuss the challenges of ordering decisions when multiple agents are involved.

In this section we will cover how to fulfill requests in a generalized consensus system.

This section discusses the fundamental governing rules of any consensus system.

This section sets the requirements for a generalized consensus system.