The Post-it switch, made real — Ranked Robin: Blue, now the outright Condorcet winner¶

Generated from bv2178_8kg698_ranked_robin.yaml — do not edit by hand. Regenerate: python STARVote_LH_tabulation_engine/tools_adam/scripts/build_yaml_pages.py.

Method: Ranked Robin (RCV-RR / Copeland) · 1 seat · Expected winner: Blue

▶ Live on BetterVoting: vote · results ↗ (election 8kg698 · test BV2178).

Official tie-break (lot) order: Purple > Green > Blue > Pink — consulted only if every deterministic tiebreaker stays tied (how the ladder works).

Scenario¶

One of four races in the Post-it switch election (BV2178, bvid 8kg698; BV-confirmed) — the BV2176/BV2177 electorate with two of the six Green>Blue>Pink voters flipping their top two (Blue>Green>Pink). In the original election the pairwise picture was a Condorcet cycle with Green and Blue tied 2-1 — the race where BetterVoting (head-to-head rung: Green) and LH (margin rung: Blue) famously part ways. The two-ballot flip dissolves all of it: Blue now beats Green 6-5 as well as Purple 10-9 and Pink 10-3 — a clean 3-0 CONDORCET WINNER. No tie, no ladder, no divergence: LH, BetterVoting, and pref_voting's independent Copeland all elect Blue. Cycles are knife-edges; two ballots is all it took to go from "two engines, two defensible winners" to unanimity. See the fairness lesson page: postit_video_fair_and_balanced.md.

Live results: https://bettervoting.com/8kg698/results Companion races: bv2178_8kg698_star.yaml, bv2178_8kg698_irv.yaml. Overview page: bv2178_8kg698_switch_made_real.md

Ballots¶

Each row is one voter's ranking, most-preferred first (N: prefix = N identical ballots).

Purple
Purple
Purple
Purple
Purple
Purple
Purple
Green>Blue>Pink
Green>Blue>Pink
Green>Blue>Pink
Green>Blue>Pink
Blue>Green>Pink
Blue>Green>Pink
Blue>Pink
Blue>Pink
Blue>Green>Pink
Blue>Purple
Pink>Green>Purple
Pink>Purple
Pink

What the engine says¶

The count, step by step — the rounds and how the winner is reached:

--- Ranked Robin (RCV-RR / Copeland) Method (single winner) ---
 Tabulating 20 ballots (ranked ballots).

Ballots:
     7 × Purple
     4 × Green > Blue > Pink
     3 × Blue > Green > Pink
     2 × Blue > Pink
     1 × Blue > Purple
     1 × Pink > Green > Purple
     1 × Pink > Purple
     1 × Pink

Round-Robin — every pair, head-to-head (For – Against):
   Purple  beats Green     9 –  8
   Blue    beats Purple   10 –  9
   Pink    beats Purple   12 –  8
   Blue    beats Green     6 –  5
   Green   beats Pink      7 –  5
   Blue    beats Pink     10 –  3

--- Pairwise (Round-Robin) Matrix ---
Head-to-head / pairwise comparison — the Ranked Robin tally
Legend: For - Equal Support - Against   (row vs column)
           |    Purple    |   Green     |    Blue     |    Pink     |
---------------------------------------------------------------------
  Purple > |     ---      | 9 -  3 -  8 | 9 -  1 - 10 | 8 -  0 - 12 |
   Green > |  8 -  3 -  9 |    ---      | 5 -  9 -  6 | 7 -  8 -  5 |
    Blue > | 10 -  1 -  9 | 6 -  9 -  5 |    ---      |10 -  7 -  3 |
    Pink > | 12 -  0 -  8 | 5 -  8 -  7 | 3 -  7 - 10 |    ---      |

Win–loss record — Copeland score = wins + ½·ties (highest score wins; ties broken by total margin, then lot order):
    #  Candidate  W–L–T  Copeland  Margin  Beats
    1  Blue       3–0–0         3      +9  Green, Purple, Pink
    2  Green      1–2–0         1      +0  Pink
    3  Purple     1–2–0         1      -4  Green
    4  Pink       1–2–0         1      -5  Purple

Winner — Ranked Robin (RCV-RR): Blue
   beats every opponent head-to-head — the Condorcet winner.

Full audit — preference matrix, Condorcet, and score distribution¶

--- Smith Set (the generalized Condorcet winner) ---
The smallest group whose every member beats every candidate outside it —
the honest answer to "who is even in contention?".
   Smith set (1 of 4): Blue
   Outside (3):        Purple, Green, Pink
   One member ⇒ Blue is the Condorcet winner, beating every rival head-to-head.
   Ranked Robin (RCV-RR) winner Blue is INSIDE the Smith set. ✓
      Guaranteed: Ranked Robin (Copeland) is Smith-efficient — every member of
      the set outscores every outsider, so the top of the win–loss table is
      always inside the set, however the tie among them is then broken.
   More: 07_Concepts/topics/smith_set.md

Everything in one file: the _tabulated mirror (regenerated on every run; every analysis forced on).

Run it yourself:

python STARVote_LH_tabulation_engine/starvote_larry_hastings.py method_comparisons/postit_rcv_example/cases/bv2178_8kg698_ranked_robin.yaml

The Post-it switch, made real — Ranked Robin: Blue, now the outright Condorcet winner¶

Scenario¶

Ballots¶

What the engine says¶

Full audit — preference matrix, Condorcet, and score distribution¶

See also¶