Polkadot Module Slides (#1000)

* old content moved, stubs for new * renames, updated readme, added zombienet, updated descriptions, updates duration, quiz stub * 13 - contributing test * Contributing to Polkadot SDK Shawn's slides converted to MD * schedule reorg * Introduction + coretime + fixed images * Execution sharding lecture re-merge * readme * time * remove light clients (merged separately) + remove stubs --------- Co-authored-by: Max Wegman <[email protected]> Co-authored-by: Shawn Tabrizi <[email protected]>
Polkadot-Blockchain-Academy · Jun 16, 2024 · ea638ab · ea638ab
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diff --git a/syllabus/7-Polkadot/1-decisions-of-polkadot-slides.md b/syllabus/7-Polkadot/1-decisions-of-polkadot-slides.md
diff --git a/syllabus/7-Polkadot/10-contributing-to-polkadot-slides.md b/syllabus/7-Polkadot/10-contributing-to-polkadot-slides.md
diff --git a/syllabus/7-Polkadot/11-XCMP-slides.md b/syllabus/7-Polkadot/11-XCMP-slides.md
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+---
+title: XCMP
+description: An overview of Cross-Chain Message Passing (XCMP) in Polkadot
+duration: 30 minutes
+owner: Shawn Tabrizi (Maciej Zyszkiewicz in backup) 
+---
+
+# XCMP
+
+---
diff --git a/syllabus/7-Polkadot/12-NPoS-slides.md b/syllabus/7-Polkadot/12-NPoS-slides.md
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+---
+title: Nominated Proof of Stake
+description: An introduction to Nominated Proof of Stake in Polkadot
+duration: 1 hour
+---
+
+# Nominated Proof of Stake
+
+## _in Polkadot_
+
+---
+
+## Why Proof of Stake Ser?
+
+Why do we use PoS?
+
+<div>
+
+- Tokens locked + prone to being slashed.
+- Economic Security 💸🤑.
+
+</div>
+
+<!-- .element: class="fragment" -->
+
+- Everything else (finality, parachains, etc.) is built on top of this base layer of economic security.
+
+<!-- .element: class="fragment" -->
+
+---v
+
+### Why Proof of Stake Ser?
+
+- Remember that Polkadot is at the end of the day a validator-set-as-a-service.
+- Secure Blockspace, the main product of Polkadot is provided by these validators.
+
+<img style="width: 1000px" src="../../assets/img/5-Substrate/dev-6-x-npos-vsas.svg" />
+<!-- [](../../assets/img/5-Substrate/dev-6-x-npos-vsas.svg) -->
+
+---
+
+## What is NPoS: Assumptions
+
+Assumptions:
+
+- **Validators**: those who intend to author blocks. i.e. _Validator candidate_.
+
+<!-- .element: class="fragment" -->
+
+- **Nominators/Delegators**: Those who intend to support wanna-be authors.
+
+<!-- .element: class="fragment" -->
+
+- Validation and nomination intentions can change, therefore we need **periodic elections** to
+  always choose the **active/winner validators/delegators** + hold them slashable.
+
+<!-- .element: class="fragment" -->
+
+- Every election period is called an **_Era_**, e.g. 24hrs in Polkadot.
+
+<!-- .element: class="fragment" -->
+
+---
+
+### What is NPoS: Re-inventing the Wheel
+
+---v
+
+**Solo-POS**
+
+<img style="width: 1000px" src="../../assets/img/5-Substrate/dev-6-x-npos-0.svg" />
+
+---v
+
+### What is NPoS: Re-inventing the Wheel
+
+- Authority-wanna-bees aka. validators bring their own stake. No further participation. Top validators are elected.
+
+- Problems?
+
+Notes:
+
+Low amount of stake that we can capture, impossible for those who don't want to run the hardware to join.
+
+---v
+
+**Single-Delegation-POS**
+
+<img style="width: 1000px" src="../../assets/img/5-Substrate/dev-6-x-npos-1.svg" />
+
+---v
+
+### What is NPoS: Re-inventing the Wheel
+
+- Anyone can dilute themselves in any given validators. Top validator based on total stake are
+  elected.
+- Voters are called **delegators**.
+
+- Problems?
+
+Notes:
+
+- Better, but funds might be delegated to non-winners, which get wasted.
+- In other words, there is no incentive to delegate to those that are non-winners.
+
+---v
+
+**Multi-Delegation-POS**
+
+<img style="width: 1000px" src="../../assets/img/5-Substrate/dev-6-x-npos-2.svg" />
+
+---v
+
+### What is NPoS: Re-inventing the Wheel
+
+Your stake is divided $\frac{1}{N}$ (or arbitrarily) among $N$ validators.
+
+Problems?
+
+Notes:
+
+Same issue as before.
+
+---v
+
+**Nominated Proof of Stake**
+
+<img style="width: 1000px" src="../../assets/img/5-Substrate/dev-6-x-npos-3.svg" />
+
+---v
+
+**Nominated Proof of Stake**
+
+<img style="width: 1000px" src="../../assets/img/5-Substrate/dev-6-x-npos-4.svg" />
+
+---v
+
+### What is NPoS: Re-inventing the Wheel
+
+- You name up to `N` nominees, an _algorithm_, computed either onchain or offchain, decides
+  the **winners** and **how to distribute the stake among them**.
+- Voters are called **Nominators**.
+
+---v
+
+### What is NPoS: Re-inventing the Wheel
+
+- ✅ As a nominator, you are free to express your desire to back non-winners as well. Once enough people have expressed the same desire, the non-winner will become a winner.
+<!-- .element: class="fragment" -->
+- ✅ Has a much higher chance to make sure staked tokens won't get wasted.
+<!-- .element: class="fragment" -->
+- ✅ Can optimize other criteria other than "who had more approval votes".
+<!-- .element: class="fragment" -->
+
+---
+
+## NPoS Drawbacks
+
+- We decided to solve an np-hard, multi-winner, approval based, election problem onchain 🤠.
+
+<pba-flex center>
+
+- scalability. <!-- .element: class="fragment" -->
+- scalability. <!-- .element: class="fragment" -->
+- scalability. <!-- .element: class="fragment" -->
+- scalability. <!-- .element: class="fragment" -->
+- and scalability. <!-- .element: class="fragment" -->
+
+</widget-text>
+
+- But we (strive to) get much better economic security measures in return 🌈.
+
+<!-- .element: class="fragment" -->
+
+- Long term, this can in itself be solved by what Polkadot provides best, more Blockspace 🎉!
+
+## <!-- .element: class="fragment" -->
+
+### NPoS Protocol Overview
+
+- The current NPoS protocol revolves around an **election round**, which is itself made up of 4
+  episodes.
+- This gives you an idea about how we solved the scalability issue for the time being.
+
+---v
+
+### NPoS Protocol Overview: Episode 1
+
+**Snapshot**
+
+- Enables multi-block election.
+- Allows us to not need to "freeze" the staking system.
+- Allows us to index stakers, not `AccountIds`.
+
+---v
+
+### NPoS Protocol Overview: Episode 2
+
+**Signed Submissions**
+
+- Any signed account can come up with a **NPoS solution** based on that snapshot.
+- Deposits, rewards, slash, other game-theoretic tools incorporated to make to secure.
+
+---v
+
+### NPoS Protocol Overview: Episode 3
+
+**Validator Submissions as Fallback**
+
+- As the first backup, any validator can also submit a solution as a part of their block authoring.
+
+---v
+
+### NPoS Protocol Overview: Episode 4
+
+**Fallbacks**
+
+- If all of the above fails, the chain won't rotate validators and the governance can either:
+  - dictate the next validator set.
+  - trigger an onchain election (limited in what it can do).
+
+## This was recently [used in Kusama](https://forum.polkadot.network/t/kusama-era-4543-slashing/1410) 🦜.
+
+## NPoS Objective
+
+- Given the powerful tool of NPoS, what should we aim for?
+- Let's first recap:
+
+1. Polkadot validators are the source of truth for the state transition of both the relay chain and all of the parachains + bridges.
+<!-- .element: class="fragment" -->
+2. Polkadot validator are assigned to parachains as backing group, and swapped over time.
+<!-- .element: class="fragment" -->
+3. Polkadot validators all author the same number of blocks, i.e. they are of same importance.
+<!-- .element: class="fragment" -->
+
+Notes:
+
+Point 2 is not to imply that the polkadot validator set's security is partitioned among parachains,
+security comes from approval voters.
+https://polkadot.network/blog/polkadot-v1-0-sharding-and-economic-security/
+
+---v
+
+### NPoS Objective: Election Score
+
+```rust
+pub struct ElectionScore {
+  /// The minimal winner, in terms of total backing stake.
+  ///
+  /// This parameter should be maximized.
+  pub minimal_stake: u128,
+  /// The sum of the total backing of all winners.
+  ///
+  /// This parameter should maximized
+  pub sum_stake: u128,
+  /// The sum squared of the total backing of all winners, aka. the variance.
+  ///
+  /// Ths parameter should be minimized.
+  pub sum_stake_squared: u128,
+}
+```
+
+---v
+
+### NPoS Objective: Election Score
+
+- NPoS allows us to incentivize the formation of a validator set that optimized the aforementioned `ElectionScore`.
+
+- This score is ALWAYS calculate and checked onchain. This is why we can accept solutions from the outer world.
+
+Notes:
+
+A common example: we allow signed submissions. What if they send solutions that are censoring a particular validator? if it can achieve a better score, so be it! we don't care.
+
+---v
+
+### NPoS Objective: Election Score
+
+- The default algorithm used in both the onchain/offchain solvers is the [Phragmen
+  algorithm](https://en.wikipedia.org/wiki/Phragmen%27s_voting_rules).
+- Proved to provide high fairness and justified representation properties whilst being verifiable in
+  linear time.
+
+---
+
+## NPoS Future
+
+- Fresh from the oven (Jan 2023): [Future of Polkadot Staking in the Polkadot forum](https://forum.polkadot.network/t/the-future-of-polkadot-staking/1848/2).
+- [Github issue-tracker/project](https://github.com/orgs/paritytech/projects/33)
+
+<hr>
+
+- Nomination Pools
+- Multi-page election submission
+- Operators as first class citizens.
+- fast-unstake.
+
+---
+
+## Additional Resources! 😋
+
+<img width="300px" rounded src="../../assets/img/5-Substrate/thats_all_folks.png" />
+
+> Check speaker notes (click "s" 😉)
+
+Notes:
+
+### Further Reading
+
+- Recent Kusama slashing: https://forum.polkadot.network/t/kusama-era-4543-slashing/1410
+- [A verifiably secure and proportional committee election rule](https://arxiv.org/abs/2004.12990)
+- 4.1 in [Overview of Polkadot and its Design Considerations](https://arxiv.org/abs/2005.13456)
+- [Proportional Justified Representation](https://arxiv.org/abs/1611.09928)
+- [Justified representation - Wikipedia](https://en.wikipedia.org/wiki/Justified_representation)
+
+### NPoS Protocol: More Details, Backup Slides
+
+- `bags-list`: how to store an unbounded semi-sorted linked-list onchain.
+- Nomination pools: best of both.
+- Minimum-untrusted score.
+- PJR checking: why we don't do it.
+- `reduce` optimization.
+
+### Feedback After Lecture: