Class BottomTwoRunoff<C>

Each round:

Rank remaining candidates by FPTP (first-choice votes).
Take the bottom-2 candidates from that ranking.
Eliminate whichever of the two loses a head-to-head FPTP matchup.

The head-to-head step in (3) is implemented by prepending tb(FirstPastThePost) to the tieBreakers array — so it will always appear as the first entry in tieBreakSteps. Any additional tieBreakers you supply are applied after FPTP if the head-to-head itself ends in a tie.

Electowiki: Bottom-Two-Runoff IRV

Type Parameters

C extends string

Hierarchy

RoundBallotMethodTb<C>
- BottomTwoRunoff

Index

Constructors

constructor

new BottomTwoRunoff<C extends string>(
    input: {
        ballots: Ballot<C>[];
        candidates: C[];
        tieBreakers?: TbEntry<C>[];
    },
): BottomTwoRunoff<C>
Type Parameters
- C extends string
Parameters
- input: { ballots: Ballot<C>[]; candidates: C[]; tieBreakers?: TbEntry<C>[] }
Returns BottomTwoRunoff<C>
Overrides RoundBallotMethodTb<C>.constructor
- Defined in methods/bottom-two-runoff/index.ts:25

Properties

`Protected` `Readonly`ballots

ballots: Ballot<C>[]

`Readonly`candidates

candidates: C[]

`Static` `Readonly`isRandom

isRandom: boolean = false

`Static` `Readonly`needsBallot

needsBallot: true

`Static` `Readonly`needsMatrix

needsMatrix: boolean = false

Accessors

matrix

get matrix(): Matrix<C>
Return a matrix of duels from all the ballots

Returns Matrix<C>
Inherited from RoundBallotMethodTb.matrix
- Defined in classes/ballot-method.ts:22

Methods

canonicalRanking

canonicalRanking(): C[][]
Returns C[][]
Inherited from RoundBallotMethodTb.canonicalRanking
- Defined in classes/method.ts:26

computeRounds

computeRounds(): Round<C>[]
Returns Round<C>[]
Inherited from RoundBallotMethodTb.computeRounds
- Defined in classes/round-ballot-method.ts:52

deTie

deTie(): C[][]
Returns C[][]
Inherited from RoundBallotMethodTb.deTie
- Defined in classes/method.ts:36

ranking

ranking(): C[][]
Result of the vote. The first item lists the winners of the vote.

For example this ranking means that Bear wins, Sheep is second and Lion third [ [ 'Bear' ], [ 'Sheep' ], [ 'Lion' ] ]

Returns C[][]
Inherited from RoundBallotMethodTb.ranking
- Defined in classes/round-ballot-method.ts:79

`Protected`resolvePending

resolvePending(
pending: C[],
): { eliminated: C[]; qualified: C[]; tieBreakSteps: TieBreakStep<C>[] }
Apply tiebreakers sequentially to a set of tied candidates. Returns qualified survivors, eliminated losers, and a trace of each step. If unresolvable, all pending are returned as eliminated.
Parameters
- pending: C[]
Returns { eliminated: C[]; qualified: C[]; tieBreakSteps: TieBreakStep<C>[] }
Inherited from RoundBallotMethodTb.resolvePending
- Defined in classes/round-ballot-method-tb.ts:150

restrict

restrict<D extends string>(candidates: D[]): BallotMethod<D>
Return a new instance of the same method restricted to a subset of candidates. Ballots are filtered to remove candidates not in the subset; unranked candidates are NOT appended (preserves only opinions voters expressed).
Type Parameters
- D extends string
Parameters
- candidates: D[]
Returns BallotMethod<D>
Inherited from RoundBallotMethodTb.restrict
- Defined in classes/ballot-method.ts:32

restrictRanking

restrictRanking<D extends string>(candidates: D[]): D[][]
Type Parameters
- D extends string
Parameters
- candidates: D[]
Returns D[][]
Inherited from RoundBallotMethodTb.restrictRanking
- Defined in classes/method.ts:32

`Protected`round

round(candidates: C[]): QE<C>
Parameters
- candidates: C[]
Returns QE<C>
Overrides RoundBallotMethodTb.round
- Defined in methods/bottom-two-runoff/index.ts:36

`Protected`roundScoresZero

roundScoresZero(candidates: C[]): ScoreObject<C>
Parameters
- candidates: C[]
Returns ScoreObject<C>
Inherited from RoundBallotMethodTb.roundScoresZero
- Defined in classes/round-ballot-method.ts:88

Class BottomTwoRunoff<C>

Electowiki: Bottom-Two-Runoff IRV

Type Parameters

Hierarchy

Index

Constructors

Properties

Accessors

Methods

Constructors

constructor

Type Parameters

Parameters

Returns BottomTwoRunoff<C>

Properties

Protected Readonlyballots

Readonlycandidates

Static ReadonlyisRandom

Static ReadonlyneedsBallot

Static ReadonlyneedsMatrix

Accessors

matrix

Returns Matrix<C>

Methods

canonicalRanking

Returns C[][]

computeRounds

Returns Round<C>[]

deTie

Returns C[][]

ranking

Returns C[][]

ProtectedresolvePending

Parameters

Returns { eliminated: C[]; qualified: C[]; tieBreakSteps: TieBreakStep<C>[] }

restrict

Type Parameters

Parameters

Returns BallotMethod<D>

restrictRanking

Type Parameters

Parameters

Returns D[][]

Protectedround

Parameters

Returns QE<C>

ProtectedroundScoresZero

Parameters

Returns ScoreObject<C>

Settings

On This Page

`Protected` `Readonly`ballots

`Readonly`candidates

`Static` `Readonly`isRandom

`Static` `Readonly`needsBallot

`Static` `Readonly`needsMatrix

`Protected`resolvePending

`Protected`round

`Protected`roundScoresZero