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Paxos Made Simple

Paxos Made Simple. Leslie Lamport.

The same two-phase majority protocol, written as pseudocode: prepare, accept, and learn.

A reading of the public document. Not a copy of it, and not a claim about a later network that reused the name.

Use this, not a blog summary, when someone claims a log is Paxos. The safety rule is the promise, not the word consensus.
Evidence
Primary paper
Re-measured
No
Assumptions
3
Records linked
2

Code

Source, repository, and what is actually hosted

  • Lamporthttps://lamport.azurewebsites.net/pubs/paxos-simple.pdf
  • The source URL is not a GitHub repository. No code remote is invented.
  • Full text is not mirrored. Public availability is not a licence to copy the file onto this site.
  • Add to a reading list

01 Claim ledger

What the paper is allowed to say

Each row is a sentence already in the study. The status is the same on every row: a model claim, not a live measurement.

  1. Claim 01 · Paper model

    The defect

    The original parliament paper is hard to implement from. Engineers needed the algorithm without the metaphor.

  2. Claim 02 · Paper model

    The rule

    The same two-phase majority protocol, written as pseudocode: prepare, accept, and learn.

  3. Claim 03 · Paper model

    How it is put together

    One leader can run many instances, one per log slot. Acceptors are the memory. Learners are the readers. A value sticks once a majority has accepted it.

  4. Claim 04 · Paper model

    Where the claim stops

    The note is not a failure detector.

02 Three cuts

Observation, model, falsifier

A desk does not stop at the summary. Each claim is cut three ways, using only this study's own assumptions and checks. Nothing here is a new figure.

  1. 01 The defect

    Observation

    What the study says

    The original parliament paper is hard to implement from. Engineers needed the algorithm without the metaphor.

    Model

    What has to hold

    The note is not a failure detector.

    Falsifier

    What would retire it

    Is each log slot its own decision?

  2. 02 The rule

    Observation

    What the study says

    The same two-phase majority protocol, written as pseudocode: prepare, accept, and learn.

    Model

    What has to hold

    It does not tell you how to choose the leader.

    Falsifier

    What would retire it

    Do learners wait for a majority or for the leader?

  3. 03 How it is put together

    Observation

    What the study says

    One leader can run many instances, one per log slot. Acceptors are the memory. Learners are the readers. A value sticks once a majority has accepted it.

    Model

    What has to hold

    It does not tell you how to choose the leader.

    Falsifier

    What would retire it

    Do learners wait for a majority or for the leader?

  4. 04 Where the claim stops

    Observation

    What the study says

    The note is not a failure detector.

    Model

    What has to hold

    The note is not a failure detector.

    Falsifier

    What would retire it

    Is each log slot its own decision?

03 Sequence

One action, as an operating tape

  1. 01The proposer picks a number higher than any it has used.
  2. 02Acceptors promise not to accept a lower number and report any accepted value.
  3. 03The proposer then asks them to accept a single safe value.
  4. 04Is each log slot its own decision?

04 Load-bearing

The argument, and where a pitch drops it

  1. Why it is still on the desk

    The cut

    Use this, not a blog summary, when someone claims a log is Paxos. The safety rule is the promise, not the word consensus.

    Why it carries weight

    If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.

    Where it is dropped

    A later client, parameter or reward formula is a different object from this paragraph.

  2. After the text

    The cut

    Production systems added leases, batching and reconfiguration. Those are extra. The ballot rule is the paper.

    Why it carries weight

    If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.

    Where it is dropped

    A later client, parameter or reward formula is a different object from this paragraph.

05 Register

What has to be true

  • Model · Not re-measured

    The note is not a failure detector.

  • Model · Not re-measured

    It does not tell you how to choose the leader.

  • Network · Not re-measured

    It does not make a network synchronous.

06 Divergence

What happened after the paper

Production systems added leases, batching and reconfiguration. Those are extra. The ballot rule is the paper.

A later client, parameter set, or reward formula is a different object. Cite this paper for the mechanism. Cite a primary release for the network. This desk has not re-run the proof.

07 Pre-mortem

What to check before you use the idea

  4. 0 of 3 marked on this browser. A mark is a reading note, not a pass, a rating, or a recommendation.

08 Anatomy

The paper, in the order a builder needs

The problem it names

The original parliament paper is hard to implement from. Engineers needed the algorithm without the metaphor.

What the design proposes

  • One leader can run many instances, one per log slot.
  • Acceptors are the memory. Learners are the readers.
  • A value sticks once a majority has accepted it.

How the mechanism is specified

  • The proposer picks a number higher than any it has used.
  • Acceptors promise not to accept a lower number and report any accepted value.
  • The proposer then asks them to accept a single safe value.

What this page does not treat as proven

  • The note is not a failure detector.
  • It does not tell you how to choose the leader.
  • It does not make a network synchronous.

Why the desk still reads it

Use this, not a blog summary, when someone claims a log is Paxos. The safety rule is the promise, not the word consensus.

09 Lexicon

Terms, opened into the record

Acceptor
A replica that stores promises and accepted values.
Proposer
A process that tries to get one value chosen.

10 Repository

Every linked record on this page

Underlined words open a page that already exists: a concept, a protocol profile, a failure record, or another paper. If a word is not underlined, this desk does not have a record for it.

Concepts

This is Blockchain Lab's reading of a public design paper. It is not the paper, not a copy of it, and not an offer of tokens, equity, custody or a partnership. Later network behaviour can diverge from the text. Nothing here is investment, legal or technical advice.

Research status: Design paper. Last reviewed: 1 October 2026. This is a reading of a public paper, not investment, legal or security advice.