Reversal symmetry — RCV-IRV, reversed: A wins AGAIN (worst = best)¶

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

Method: RCV-IRV (Instant Runoff) · 1 seat · Expected winner: A

Scenario¶

The original election (reversal_irv_original) with EVERY voter's ballot reversed — each now expresses the exact opposite preference, as if trying to elect the WORST candidate. You would expect A (the original winner) to now finish last. Instead RCV-IRV elects A AGAIN (16-8): B has the fewest first-choices, is eliminated, and B's ballots flow to A. So IRV's "best" candidate and its "worst" candidate are the same — a reversal symmetry FAILURE. This is a real, IRV-specific defect (concede it). Caveats on ../README.md: the electorate is a Condorcet cycle, so there is no "correct" winner; STAR gives B then A (no winner=loser); source is Range-advocacy (lean disclosed).

Ballots¶

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

9:A>C>B
8:C>B>A
7:B>A>C

What the engine says¶

Round-by-round Sankey diagram: each candidate's votes as a band, and where the votes of an eliminated candidate transferred to.

Where the votes went. Band thickness is votes; a band leaving an eliminated candidate lands on whoever that ballot ranked next, or on inactive if it ranked nobody who was left.

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

--- RCV / Instant-Runoff Voting (single winner) ---
  Reversal symmetry — RCV-IRV, reversed: A wins AGAIN (worst = best)
 Tabulating 24 ballots (ranked ballots).

ROUND 1
Candidate      Votes  Status
-----------  -------  --------
A                  9  Hopeful
C                  8  Hopeful
B                  7  Rejected

FINAL RESULT
Candidate      Votes  Status
-----------  -------  --------
A                 16  Elected
C                  8  Rejected
B                  0  Rejected


Winner(s) — RCV / Instant-Runoff Voting (single winner)
  A

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 (3 of 3): A, C, B
   Outside (0):        —
   More than one member ⇒ NO Condorcet winner: the top of the tournament is a
   cycle, so the strongest "candidate" is a set, not a person. Which member of
   the set should win is exactly what Minimax / Ranked Pairs / Schulze disagree
   about — see 05_Ranked_Robin/01_Learn/cycle_resolution.md.
   RCV-IRV winner A is INSIDE the Smith set. ✓
      Not guaranteed — RCV-IRV is not Smith-efficient — but it holds here.
   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/reversal_symmetry/cases/reversal_irv_reversed.yaml

Reversal symmetry — RCV-IRV, reversed: A wins AGAIN (worst = best)¶

Scenario¶

Ballots¶

What the engine says¶

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

See also¶