====================================================================== SOURCE FILE: felsenthal_ex6_ranked_robin.yaml TABULATED FILE: felsenthal_ex6_ranked_robin_tabulated.txt ====================================================================== election_title: "Felsenthal Ex.6 — Ranked Robin: the Pareto-dominant Condorcet winner Aria (LH-only)" scenario_description: |- LH-only companion to felsenthal_ex6_pareto_approval.yaml (no BetterVoting election — see that file for why). Source: Dan S. Felsenthal (2010), Appendix A3, Example 6, due to Felsenthal & Maoz (1988: 123, Example 4). The same 3 voters' full rankings counted by Ranked Robin (Copeland): Aria wins every head-to-head — Beau 3–0 (every single voter prefers Aria to Beau: Pareto dominance), Cole 2–1, Dean 2–1 — the Condorcet winner, elected outright. The approval count in the companion file loses this information because the top-three approval cutoff puts Aria and Beau in the same bucket on every ballot. paradoxes: [pareto] voting_method: RankedRobin num_winners: 1 ballots: |- 1:Aria>Beau>Cole>Dean 1:Cole>Aria>Beau>Dean 1:Dean>Aria>Beau>Cole expected_winners: - Aria # file: felsenthal_ex6_ranked_robin.yaml ====================================================================== TABULATION RESULTS ====================================================================== --- Ranked Robin (RCV-RR / Copeland) Method (single winner) --- Tabulating 3 ballots (ranked ballots). Ballots: 1 × Aria > Beau > Cole > Dean 1 × Cole > Aria > Beau > Dean 1 × Dean > Aria > Beau > Cole Round-Robin — every pair, head-to-head (For – Against): Aria beats Beau 3 – 0 Aria beats Cole 2 – 1 Aria beats Dean 2 – 1 Beau beats Cole 2 – 1 Beau beats Dean 2 – 1 Cole beats Dean 2 – 1 --- Pairwise (Round-Robin) Matrix --- Head-to-head / pairwise comparison — the Ranked Robin tally Legend: For - Equal Support - Against (row vs column) | Aria | Beau | Cole | Dean | ------------------------------------------------------- Aria > | --- |3 - 0 - 0 |2 - 0 - 1 |2 - 0 - 1 | Beau > | 0 - 0 - 3 | --- |2 - 0 - 1 |2 - 0 - 1 | Cole > | 1 - 0 - 2 |1 - 0 - 2 | --- |2 - 0 - 1 | Dean > | 1 - 0 - 2 |1 - 0 - 2 |1 - 0 - 2 | --- | 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 Aria 3–0–0 3 +5 Beau, Cole, Dean 2 Beau 2–1–0 2 -1 Cole, Dean 3 Cole 1–2–0 1 -1 Dean 4 Dean 0–3–0 0 -3 — Winner — Ranked Robin (RCV-RR): Aria beats every opponent head-to-head — the Condorcet winner. --- 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): Aria Outside (3): Beau, Cole, Dean One member ⇒ Aria is the Condorcet winner, beating every rival head-to-head. Ranked Robin (RCV-RR) winner Aria 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