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LibraryConsensus1988Design paperCorpus record

Consensus in the Presence of Partial Synchrony

Partial Synchrony. Cynthia Dwork, Nancy Lynch and Larry Stockmeyer.

Safety can hold with no timing assumption. Liveness can wait for a period, after some unknown instant, when messages arrive within a bound.

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

Ask a BFT designer which property dies when packets are late. If the answer is safety, they are not in this model.
Evidence
Primary paper
Re-measured
No
Assumptions
3
Records linked
4

Code

Source, repository, and what is actually hosted

  • Journal of the ACMhttps://groups.csail.mit.edu/tds/papers/Lynch/jacm88.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

    Fully asynchronous consensus with even one fault is impossible, and a fully synchronous network is a fairy tale.

  2. Claim 02 · Paper model

    The rule

    Safety can hold with no timing assumption. Liveness can wait for a period, after some unknown instant, when messages arrive within a bound.

  3. Claim 03 · Paper model

    How it is put together

    The GST, the global stabilisation time, is unknown to the protocol. Timeouts can be used for liveness without being used for safety. The model sits between FLP and a lockstep network.

  4. Claim 04 · Paper model

    Where the claim stops

    Partial synchrony is a model, not a product.

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

    Fully asynchronous consensus with even one fault is impossible, and a fully synchronous network is a fairy tale.

    Model

    What has to hold

    Partial synchrony is a model, not a product.

    Falsifier

    What would retire it

    What is the fault threshold in the model they claim?

  2. 02 The rule

    Observation

    What the study says

    Safety can hold with no timing assumption. Liveness can wait for a period, after some unknown instant, when messages arrive within a bound.

    Model

    What has to hold

    It does not excuse a chain that reorgs committed blocks.

    Falsifier

    What would retire it

    Does a committed decision ever roll back when messages are delayed?

  3. 03 How it is put together

    Observation

    What the study says

    The GST, the global stabilisation time, is unknown to the protocol. Timeouts can be used for liveness without being used for safety. The model sits between FLP and a lockstep network.

    Model

    What has to hold

    Timeouts in the implementation may be cruder than the model.

    Falsifier

    What would retire it

    What is the fault threshold in the model they claim?

  4. 04 Where the claim stops

    Observation

    What the study says

    Partial synchrony is a model, not a product.

    Model

    What has to hold

    Partial synchrony is a model, not a product.

    Falsifier

    What would retire it

    What is the fault threshold in the model they claim?

03 Sequence

One action, as an operating tape

  1. 01Processes propose. Agreement and validity are required even while the network is wild.
  2. 02After GST, honest messages get through and a decision is reached.
  3. 03A protocol that forks when messages are late has put safety on the clock.
  4. 04Does a committed decision ever roll back when messages are delayed?

04 Load-bearing

The argument, and where a pitch drops it

  1. Why it is still on the desk

    The cut

    Ask a BFT designer which property dies when packets are late. If the answer is safety, they are not in this model.

    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

    Partial synchrony is a model, not a product.

  2. After the text

    The cut

    PBFT and HotStuff cite this split. Nakamoto consensus does not: its confirmation is probabilistic and timing is the security assumption.

    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

  • Network · Not re-measured

    Partial synchrony is a model, not a product.

  • Model · Not re-measured

    It does not excuse a chain that reorgs committed blocks.

  • Model · Not re-measured

    Timeouts in the implementation may be cruder than the model.

06 Divergence

What happened after the paper

PBFT and HotStuff cite this split. Nakamoto consensus does not: its confirmation is probabilistic and timing is the security assumption.

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

Fully asynchronous consensus with even one fault is impossible, and a fully synchronous network is a fairy tale.

What the design proposes

  • The GST, the global stabilisation time, is unknown to the protocol.
  • Timeouts can be used for liveness without being used for safety.
  • The model sits between FLP and a lockstep network.

How the mechanism is specified

  • Processes propose. Agreement and validity are required even while the network is wild.
  • After GST, honest messages get through and a decision is reached.
  • A protocol that forks when messages are late has put safety on the clock.

What this page does not treat as proven

  • Partial synchrony is a model, not a product.
  • It does not excuse a chain that reorgs committed blocks.
  • Timeouts in the implementation may be cruder than the model.

Why the desk still reads it

Ask a BFT designer which property dies when packets are late. If the answer is safety, they are not in this model.

09 Lexicon

Terms, opened into the record

GST
An unknown time after which the network behaves for long enough.
Safety
Two honest parties never decide differently.

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.