Matic Network white paper

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

   Fast blocks live on the sidechain

   Users transact against a Matic chain that does not wait for Ethereum's block time. The paper's speed is this separation.

2. Claim 02 · Paper model

   Checkpoints are the bridge back

   Producers periodically commit a hash of the sidechain to Ethereum. That commitment is what a later withdrawal or dispute refers to.

3. Claim 03 · Paper model

   Fraud proofs are the enforcement

   If a checkpoint is wrong, a challenger is supposed to prove it on Ethereum during a window. The sidechain's honesty is economically enforced by that window and by stakes.

4. Claim 04 · Paper model

   Plasma is in the ancestry

   The paper sits in the family of commit-and-challenge designs. It specialises the machinery for a general sidechain with its own producers. Later Polygon systems added other proofs. This text is the checkpoint design.

5. Claim 05 · Paper model

   Deposits and withdrawals are different speeds

   Entering can be as fast as an Ethereum deposit plus a sidechain credit. Leaving waits on the checkpoint and the challenge period. The paper's user experience is asymmetric, and it should be described that way.

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 Fast blocks live on the sidechain

   Observation

   What the study says

   Users transact against a Matic chain that does not wait for Ethereum's block time. The paper's speed is this separation.

   Model

   What has to hold

   Ethereum will include that challenge. Prolonged censorship on the root is a sidechain failure mode.

   Falsifier

   What would retire it

   Is a sidechain balance being described as final on Ethereum before the window?

2. 02 Checkpoints are the bridge back

   Observation

   What the study says

   Producers periodically commit a hash of the sidechain to Ethereum. That commitment is what a later withdrawal or dispute refers to.

   Model

   What has to hold

   Ethereum will include that challenge. Prolonged censorship on the root is a sidechain failure mode.

   Falsifier

   What would retire it

   Is a sidechain balance being described as final on Ethereum before the window?

3. 03 Fraud proofs are the enforcement

   Observation

   What the study says

   If a checkpoint is wrong, a challenger is supposed to prove it on Ethereum during a window. The sidechain's honesty is economically enforced by that window and by stakes.

   Model

   What has to hold

   At least one watcher will challenge a bad checkpoint before the window ends.

   Falsifier

   What would retire it

   Is a sidechain balance being described as final on Ethereum before the window?

4. 04 Plasma is in the ancestry

   Observation

   What the study says

   The paper sits in the family of commit-and-challenge designs. It specialises the machinery for a general sidechain with its own producers. Later Polygon systems added other proofs. This text is the checkpoint design.

   Model

   What has to hold

   At least one watcher will challenge a bad checkpoint before the window ends.

   Falsifier

   What would retire it

   Is the system being cited the 2019 checkpoint chain or a later zk design?

5. 05 Deposits and withdrawals are different speeds

   Observation

   What the study says

   Entering can be as fast as an Ethereum deposit plus a sidechain credit. Leaving waits on the checkpoint and the challenge period. The paper's user experience is asymmetric, and it should be described that way.

   Model

   What has to hold

   Ethereum will include that challenge. Prolonged censorship on the root is a sidechain failure mode.

   Falsifier

   What would retire it

   Is a sidechain balance being described as final on Ethereum before the window?

03 Sequence

One action, as an operating tape

1. 01A user locks an asset on Ethereum in the root contract.
2. 02The sidechain credits the user and processes transactions under its proof-of-stake producers.
3. 03Producers publish a checkpoint of the resulting state to the root contract.
4. 04A withdrawal asks Ethereum to honour the checkpoint after the challenge window, or sooner if a later variant says so.
5. 05A challenger who shows the checkpoint does not follow the sidechain's rules can get it rolled back and the producer slashed, under the paper's dispute rules.

04 Load-bearing

The argument, and where a pitch drops it

1. A checkpoint is a claim

   The cut

   Until the window passes, Ethereum has been told a story by the producers. Users who treat the sidechain balance as already an Ethereum balance are early. The paper's security clock and the application's marketing clock are easy to confuse.

   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 checkpoint of a hash is not a validity proof. The paper's security story has to be read for what it actually checks.

2. Producer stake has to hurt

   The cut

   Fraud proofs work if the producers lose more than they gain by lying, and if someone can post the proof. A small stake and a censored challenge transaction are both fatal, in different ways.

   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 checkpoint of a hash is not a validity proof. The paper's security story has to be read for what it actually checks.

3. Later Polygon is a portfolio

   The cut

   The name came to cover a proof-of-stake chain, zk systems and app-chains. The 2019 paper does not describe all of them. A study that uses 'Polygon' to mean this checkpoint scheme should say so in the first paragraph.

   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

   Do not describe today's Polygon PoS chain as 'the Matic white paper, implemented verbatim'.

05 Register

What has to be true

• Model · Not re-measured

  At least one watcher will challenge a bad checkpoint before the window ends.

• Model · Not re-measured

  Ethereum will include that challenge. Prolonged censorship on the root is a sidechain failure mode.

• Data · Not re-measured

  The state committed is the state users can download. Withheld data recreates the Plasma problem.

• Stake and threshold · Not re-measured

  Producer stake is large relative to the value a false checkpoint could extract.

06 Divergence

What happened after the paper

Matic became Polygon. The proof-of-stake chain and its Ethereum checkpoints shipped, and the company later pursued zk rollups and other stacks. Withdrawal delays and the role of Ethereum in the original paper remain the right questions, even when a newer stack answers them with a validity proof instead of a challenge window.

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

1. Kill test 1How often is a checkpoint posted, and how long is the challenge window?
2. Kill test 2Who can challenge, and what do they need to store?
3. Kill test 3Is a sidechain balance being described as final on Ethereum before the window?
4. Kill test 4Is the system being cited the 2019 checkpoint chain or a later zk design?
5. 0 of 4 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

09 Lexicon

Terms, opened into the record

Checkpoint

A hash of sidechain state posted to Ethereum, which withdrawals and disputes refer to.

Challenge window

The period during which a bad checkpoint can be proven false on the root chain.

Sidechain

A chain with its own producers, whose link to Ethereum is the checkpoint rather than re-execution.

Root contract

The Ethereum contract that holds deposits and judges checkpoints.

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.

11 Related

The next papers, as theses

• Plasma · 2017

  Plasma: Scalable Autonomous Smart Contracts

  A 2017 construction for trees of child chains whose state commitments are posted to a parent chain, with exits so a user can leave if the child operator misbehaves. It is an ancestor of later rollup and validium designs, not a synonym for them.

• Arbitrum · 2018

  Arbitrum: Scalable, private smart contracts

  The 2018 USENIX paper on Arbitrum: a verifier that checks a manager's execution of a virtual machine by bisecting disputes, instead of re-executing every instruction. Offchain Labs' later Nitro stack is a descendant, not this paper line for line.

• Polkadot · 2016

  Polkadot: Vision for a heterogeneous multi-chain framework

  Wood's 2016 vision paper: a relay chain that provides shared security and a queue of cross-chain messages, with parachains that keep their own state transition. It is a vision paper. The live protocol has a specification of its own.