LibraryConsensus2016Design paperCorpus record
Flexible Paxos: Quorum Intersection Revisited
Flexible Paxos. Heidi Howard, Dahlia Malkhi and Alexander Spiegelman.
Only quorums from different phases have to intersect. A phase-1 quorum and a phase-2 quorum must overlap. Two phase-2 quorums need not.
A reading of the public document. Not a copy of it, and not a claim about a later network that reused the name.
A system that boasts a fast quorum should say which phase got smaller and which intersection it still guarantees.
- Evidence
- Primary paper
- Re-measured
- No
- Assumptions
- 3
- Records linked
- 2
Code
Source, repository, and what is actually hosted
- arXiv:1608.06696https://arxiv.org/pdf/1608.06696
- 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.
Claim 01 · Paper model
The defect
Classic Paxos uses the same majority for every phase. That is sufficient, not necessary.
Claim 02 · Paper model
The rule
Only quorums from different phases have to intersect. A phase-1 quorum and a phase-2 quorum must overlap. Two phase-2 quorums need not.
Claim 03 · Paper model
How it is put together
You can make the common case, acceptance, a smaller quorum. You pay for that with a larger prepare quorum. Safety is still the intersection, not the word majority.
Claim 04 · Paper model
Where the claim stops
Flexible Paxos does not remove the need for a known set.
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.
01 The defect
02 The rule
Observation
What the study says
Only quorums from different phases have to intersect. A phase-1 quorum and a phase-2 quorum must overlap. Two phase-2 quorums need not.
Model
What has to hold
It is not a licence to pick quorums that miss each other.
Falsifier
What would retire it
Do phase-1 and phase-2 quorums intersect?
03 How it is put together
Observation
What the study says
You can make the common case, acceptance, a smaller quorum. You pay for that with a larger prepare quorum. Safety is still the intersection, not the word majority.
Model
What has to hold
It does not add Byzantine faults by itself.
Falsifier
What would retire it
What fails if an operator shrinks both?
04 Where the claim stops
03 Sequence
One action, as an operating tape
- 01Name the prepare quorum and the accept quorum separately.
- 02Check that every prepare quorum hits every accept quorum.
- 03Run the common path on the smaller one.
- 04Do phase-1 and phase-2 quorums intersect?
04 Load-bearing
The argument, and where a pitch drops it
Why it is still on the desk
The cut
A system that boasts a fast quorum should say which phase got smaller and which intersection it still guarantees.
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.
After the text
The cut
Later consensus systems treat quorum choice as a parameter. The 2016 note is the reason that parameter is not free.
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
Flexible Paxos does not remove the need for a known set.
Stake and threshold · Not re-measured
It is not a licence to pick quorums that miss each other.
Stake and threshold · Not re-measured
It does not add Byzantine faults by itself.
06 Divergence
What happened after the paper
Later consensus systems treat quorum choice as a parameter. The 2016 note is the reason that parameter is not free.
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
- 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
Classic Paxos uses the same majority for every phase. That is sufficient, not necessary.
What the design proposes
- You can make the common case, acceptance, a smaller quorum.
- You pay for that with a larger prepare quorum.
- Safety is still the intersection, not the word majority.
How the mechanism is specified
- Name the prepare quorum and the accept quorum separately.
- Check that every prepare quorum hits every accept quorum.
- Run the common path on the smaller one.
What this page does not treat as proven
- Flexible Paxos does not remove the need for a known set.
- It is not a licence to pick quorums that miss each other.
- It does not add Byzantine faults by itself.
Why the desk still reads it
A system that boasts a fast quorum should say which phase got smaller and which intersection it still guarantees.
09 Lexicon
Terms, opened into the record
- Phase 1
- The prepare that discovers a value that might already be chosen.
- Phase 2
- The accept that tries to choose a value.
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
Papers
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.