Active set expansions, what do they do?

Recently I have seen many people attribute an expansion in the active set by the Technical Committee as being directly correlated with certain validators getting into the active set, and wanted to clarify this for everyone.

The expansion in the active set as proposed and decided by the Technical committee, simply increases the number in which Phragmen Algorithm calculates each era’s active set on.

These expansions in the active set by the Technical Committee do not select validators A,B,C.

For example:
Active set params are at 72 operators.
Phragmen calculates out of the whole waiting list, who are the 72 operators that provide the most economic security to the chain.

Active set params then change to 77 (as the proposal just passed will enact later this week).
Phragmen is then calculating for the 77 validators out of the entire waitlist that provide the most economic security to the chain for the following days era.

So then how does a validator ensure they get selected?
A validators total stake is the primary factor in being selected for on chain operations by Phragmen.
Increasing your validators total stake is the goal!
Whether this is via the nomination program + retail stake, or retail stake alone, the more stake you have, the more chance you have of being selected for each days operations.

More on Phragmen:
Since validators are paid almost equally in in each era, it is important that the stake behind each validator is uniformly spread out. Phragmen algorithm will try to optimize three metrics when computing a solution graph of nominators and validators:

  1. Maximize the total amount at stake.
  2. Maximize the stake behind the minimally staked validator.
  3. Minimize the variance of the stake in the set.**

This means that as the active set number is set to 77, 77 validators will be chosen for tomorrow’s active set (out of the entire bonded waitlist), and the following day it may well be exactly the same 77, or change, if the stake ratios between certain operators has shifted enough.

How does the nomination program fit into this?
The Nomination Program Committee, approves wait-listed validators to receive nominations from the Foundation.

As Phragmen is selecting validators for on chain operations based on stake, a nomination from the foundation assists validators in being selected by Phragmen for on chain operations.

Conclusion:
Total stake (foundation provided or retail provided) goes towards being selected for on chain operations by Phragmen in its daily calculation.
If the lowest staked active set validator has 20m Avail today, and someone comes in and stakes 22m Avail today, most likely Phragmen will switch them in for that lower staked validator for the following Era.

The expansions in the active set as managed by the TC simply changes the amount of validators in each era in the Phragmen calculation, it does not select those validators.

The selection is done by Phragmen each day for the following Era.
This means, that the expansions in the active

6 Likes