====================================================================== SOURCE FILE: felsenthal_ex6_pareto_approval.yaml TABULATED FILE: felsenthal_ex6_pareto_approval_tabulated.txt ====================================================================== election_title: "Felsenthal Ex.6 — Approval can elect a Pareto-dominated candidate (LH-only)" scenario_description: |- LH-only reference (no BetterVoting election ON PURPOSE: the paradox turns on a RANDOM Aria/Beau tie, and a random BV result can't be frozen — compare the RR tiebreak study). Source: Dan S. Felsenthal, "Review of Paradoxes Afflicting Various Voting Procedures Where One Out of m Candidates (m ≥ 2) Must Be Elected", University of Haifa / LSE, revised 26 May 2010; Appendix A3, Example 6 — due to Felsenthal & Maoz (1988: 123, Example 4). 3 voters, four candidates, rankings: Aria>Beau>Cole>Dean; Cole>Aria>Beau>Dean; Dean>Aria>Beau>Cole. EVERY voter prefers Aria to Beau (Aria Pareto-dominates Beau), and Aria is the Condorcet winner. But if each voter approves their top THREE, the approval totals are Aria 3, Beau 3, Cole 2, Dean 1 — a tie between Aria and Beau. Broken randomly, there is a 0.5 chance BEAU is elected: a Pareto-dominated candidate can win under Approval. This file pins the lot order adversarially (Beau first) to exhibit exactly that branch; the companion felsenthal_ex6_ranked_robin.yaml shows the same voters' rankings electing Aria. paradoxes: [pareto, condorcet-winner] voting_method: Approval num_winners: 1 # Adversarial lot: Beau first, so the 3-3 Aria/Beau approval tie resolves to the # Pareto-dominated candidate — the 0.5 branch Felsenthal's text warns about. lot_numbers: [Beau, Aria, Cole, Dean] ballots: |- Aria,Beau,Cole,Dean 1,1,1,0 1,1,1,0 1,1,0,1 expected_winners: - Beau # file: felsenthal_ex6_pareto_approval.yaml ====================================================================== TABULATION RESULTS ====================================================================== --- Approval Voting (single winner) --- Tabulating 3 ballots (any non-zero score = approval). Ballots: columns = Aria, Beau, Cole, Dean (1 = approve; 0 = not approved) 2 × 1,1,1,0 1 × 1,1,0,1 Beau -- 3 (100%) -- Elected Aria -- 3 (100%) Cole -- 2 (67%) Dean -- 1 (33%) Note: Beau, Aria each have 3 approvals and tie for the last 1 seat. Candidate priority order (Beau > Aria) broke the tie: Beau elected, Aria not elected. [Approval Distribution] (how many candidates each ballot approved) 9 approvals across 3 ballots — average 3.0 of 4 (range 3–3). approved 3: 3 ballots [Co-Approval Matrix] Of the voters who approved the ROW candidate, the % who ALSO approved the COLUMN candidate. | Beau | Aria | Cole | Dean | ------------------------------------------- Beau | -- | 100% | 67% | 33% | Aria | 100% | -- | 67% | 33% | Cole | 100% | 100% | -- | 0% | Dean | 100% | 100% | 0% | -- | Winner — Approval Voting (single winner) Beau