Center Squeeze — Ranked Robin (Copeland): the Condorcet winner survives¶

Generated from bv2137_ywckmg_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: Anderson

▶ Live on BetterVoting: vote · results ↗ (election ywckmg · test BV2137).

Official tie-break (lot) order: Anderson > Carter > Reagan — consulted only if every deterministic tiebreaker stays tied (how the ladder works).

Scenario¶

One of four races in the Center Squeeze election (BV2137, bvid ywckmg; BV-confirmed). 100 voters, three candidates, ONE ranked electorate tabulated four ways. Anderson is the Condorcet winner (beats Reagan 55–45, Carter 65–35) but holds the fewest first-choices (20). Ranked Robin counts head-to-heads: Anderson beats BOTH rivals, so RR → Anderson — the Condorcet winner IRV threw away.

Ballots¶

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

45:Reagan>Anderson>Carter
20:Anderson>Carter>Reagan
35:Carter>Anderson>Reagan

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 100 ballots (ranked ballots).

Ballots:
    45 × Reagan > Anderson > Carter
    20 × Anderson > Carter > Reagan
    35 × Carter > Anderson > Reagan

Round-Robin — every pair, head-to-head (For – Against):
   Anderson  beats Reagan     55 – 45
   Carter    beats Reagan     55 – 45
   Anderson  beats Carter     65 – 35

--- Pairwise (Round-Robin) Matrix ---
Head-to-head / pairwise comparison — the Ranked Robin tally
Legend: For - Equal Support - Against   (row vs column)
             |    Reagan    |  Anderson   |   Carter    |
---------------------------------------------------------
    Reagan > |     ---      |45 -  0 - 55 |45 -  0 - 55 |
  Anderson > | 55 -  0 - 45 |    ---      |65 -  0 - 35 |
    Carter > | 55 -  0 - 45 |35 -  0 - 65 |    ---      |

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  Anderson   2–0–0         2     +40  Carter, Reagan
    2  Carter     1–1–0         1     -20  Reagan
    3  Reagan     0–2–0         0     -20  —

Winner — Ranked Robin (RCV-RR): Anderson
   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 3): Anderson
   Outside (2):        Reagan, Carter
   One member ⇒ Anderson is the Condorcet winner, beating every rival head-to-head.
   Ranked Robin (RCV-RR) winner Anderson 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/center_squeeze_bv2137/cases/bv2137_ywckmg_ranked_robin.yaml

Center Squeeze — Ranked Robin (Copeland): the Condorcet winner survives¶

Scenario¶

Ballots¶

What the engine says¶

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

See also¶