This topic is about reducing fixed node dominance by increasing committee size. It will address some questions and (hopefully) further clarify the response detailed here: Incognito 2022: Technical Roadmap
Seasoned validators will be familiar with a lot of this info, but i’ll include some details here for general readers too.
Incognito is a Proof of Stake network that needs at least 68.75% committee votes for a newly created block to be added to the blockchain. The committee size is currently 32. The core team has 22 fixed nodes to keep the network stable at this early stage. This is not decentralized; in other words, a new proposed block will be created and verified by these 22 fixed nodes with or without community nodes.
After a rough start when slashing was implemented and non-functioning community nodes plummeted, all nodes are performing much better, and so should have more voting power.
1. Why is increasing committee size better for decentralization and security than reducing fixed slots?
Both options result in the same % reduction of fixed nodes dominance. However, in the option where committee size remains the same, fixed nodes just need to collude with 7 community nodes to produce a malicious block. If committee size is increased, they will need to collude with 11 community nodes to do so (11 and 22 respectively for phase 2).
2. Why is increasing committee size important groundwork?
Increasing committee size is a thing that needs to happen at some point anyway. When fixed node dominance is less, we need as many healthy nodes as possible to ensure stability. The more healthy nodes in the committee, the better. We have outlined this in past proposals and roadmaps ([Shipped] Dynamic committee size).
Quick summary of the dynamic committee size project: max committee size will be increased to 48 and 64 slots in 2 phases to reduce fixed node dominance to 46% and 34% respectively. Please note that these are max committee sizes; the actual size may dynamically increase or decrease depending on network stability.
TLDR for points 1 and 2: Reducing fixed nodes vs. increasing committee size may result in the same percentage of dominance, but the second is a more secure way to increase decentralization, and is a better decision for the long term.
3. What does this mean for processing power needed?
CPU usage is only high if a node has to re-sync data of a new shard from scratch. As long as it’s not slashed to be randomly reassigned to a new shard, it can continue syncing data of the same shard. This is very lightweight. In a PoS network, the CPU cost for participating in consensus is not significant.
4. How does increasing committee size not dilute earnings?
Increasing committee size means a node will stay in a committee longer; the reward per block may be divided among more nodes, but the earning period will be extended. Additionally, expanding committee size also means community nodes on the whole will increasingly take the majority of earnings.
Currently, in a committee, fixed nodes earn about 68.75% of block rewards for shard committees since they occupy 22 out of 32 slots. When fixed node dominance is decreased to 46% (22 out of 48 slots in a committee), community nodes will earn about 54% of block rewards for shard committees and fixed nodes will earn 46%.
Similarly, when we decrease fixed node dominance to 34% (22 out of 64 slots in a committee) community nodes will earn about 66% of block rewards for shard committees and fixed nodes will earn 34%.
These 2 phases are just the start. The long term goal is still to continue working to reduce fixed slots to as small an amount as possible.
Ideally, only a few block proposers will be needed for fault tolerance.
5. What is a block proposer?
A proposer is a validator that proposes a new block; other nodes then verify the proposed block.
I hope this helps. Please let me know if you have any further questions or concerns, and we’ll do our best to answer them.