BV2143 — clone independence (2/2): teaming succeeds on LH, fails on BetterVoting¶

Method: Ranked Robin (RCV-RR / Copeland) · 1 seat · Expected winner: A1 · full count →

▶ Live on BetterVoting: vote · results ↗ (election 9pr3wr).

Part 2 of the electowiki clone-independence pair (the "after"). Same electorate as BV2142, but the A-faction runs clones — and the two engines elect different winners from identical ballots. Full lesson: rr_clone_independence.md.

The teaming ballots¶

The A-faction fields A1 and A2 (ranked together in A's old slot):

12:A1>A2>B>C>D>E>F
11:B>C>A1>A2>D>E>F
10:C>A1>A2>B>D>E>F

A1 and C tie at 5 wins. Whether teaming works comes down to the tiebreak.

View 1 — BetterVoting: head-to-head → C (teaming fails)¶

BV breaks the 2-way tie by head-to-head, and C beats A1, 21–12:

tied: [], tieBreakType: none
elected: [C]; log: "C preferred over A1 in runoff."

BetterVoting result page for 9pr3wr: headline 'C wins!', 33 voters, Voting Method: Ranked Robin. Head-to-head wins bars — A1 83% and C 83% (5 of 6 matchups each), B 67%, A2 67%, D 33%, E 17%, F 0%.

Read the chart carefully: BV's ⭐ sits on the top bar, which here is A1 — but the headline elects C. The bars only show the 5-wins tie; the head-to-head rung that settles it isn't in the chart.

So on BetterVoting the clones did not help the A-faction — C wins. Deterministic and freezable: bv2143_9pr3wr_teaming_fails_bv_export.json.

View 2 — LH: margin → A1 (teaming succeeds)¶

LH breaks the tie by total margin, and A1 (+134) beats C (+104):

    #  Candidate  W–L–T  Copeland  Margin  Beats
    1  A1         5–1–0         5    +134  B, A2, D, E, F
    2  C          5–1–0         5    +104  A1, A2, D, E, F
    3  B          4–2–0         4     +90  C, D, E, F
    4  A2         4–2–0         4     +68  B, D, E, F
Winner — Ranked Robin (RCV-RR): A1

By running clones the A-faction pushed B out of the top tier and lifted A1's margin above C — under a margin tiebreak the teaming succeeds (A1 wins). Full LH detail: _tabulated.

The takeaway¶

Same ballots, opposite winners: LH (margin) → A1, BV (head-to-head) → C. The clone-independence failure is a property of the margin tiebreak (LH, and the Equal Vote protocol), not of Ranked Robin as such — BV's head-to-head rung happens to resist this teaming. See rr_tiebreak_lh_vs_bv.md.