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2 stable releases
2.0.2 | Apr 3, 2021 |
---|---|
2.0.1 | Apr 2, 2021 |
#11 in #tetcoin
145 downloads per month
Used in 16 crates
(3 directly)
550KB
12K
SLoC
A set of election algorithms to be used with a tetcore runtime, typically within the staking sub-system. Notable implementation include:
seq_phragmen
: Implements the Phragmén Sequential Method. An un-ranked, relatively fast election method that ensures PJR, but does not provide a constant factor approximation of the maximin problem.phragmms
: Implements a hybrid approach inspired by Phragmén which is executed faster but it can achieve a constant factor approximation of the maximin problem, similar to that of the MMS algorithm.balance_solution
: Implements the star balancing algorithm. This iterative process can push a solution toward being morebalances
, which in turn can increase its score.
Terminology
This crate uses context-independent words, not to be confused with staking. This is because the election algorithms of this crate, while designed for staking, can be used in other contexts as well.
Voter
: The entity casting some votes to a number of Targets
. This is the same as Nominator
in the context of staking. Target
: The entities eligible to be voted upon. This is the same as
Validator
in the context of staking. Edge
: A mapping from a Voter
to a Target
.
The goal of an election algorithm is to provide an ElectionResult
. A data composed of:
winners
: A flat list of identifiers belonging to those who have won the election, usually ordered in some meaningful way. They are zipped with their total backing stake.assignment
: A mapping from each voter to their winner-only targets, zipped with a ration denoting the amount of support given to that particular target.
// the winners.
let winners = vec![(1, 100), (2, 50)];
let assignments = vec![
// A voter, giving equal backing to both 1 and 2.
Assignment {
who: 10,
distribution: vec![(1, Perbill::from_percent(50)), (2, Perbill::from_percent(50))],
},
// A voter, Only backing 1.
Assignment { who: 20, distribution: vec![(1, Perbill::from_percent(100))] },
];
// the combination of the two makes the election result.
let election_result = ElectionResult { winners, assignments };
The Assignment
field of the election result is voter-major, i.e. it is from the perspective of
the voter. The struct that represents the opposite is called a Support
. This struct is usually
accessed in a map-like manner, i.e. keyed vy voters, therefor it is stored as a mapping called
SupportMap
.
Moreover, the support is built from absolute backing values, not ratios like the example above.
A struct similar to Assignment
that has stake value instead of ratios is called an
StakedAssignment
.
More information can be found at: https://arxiv.org/abs/2004.12990
License: Apache-2.0
Dependencies
~3–12MB
~122K SLoC