====================================================================== SOURCE FILE: rr_combined.yaml TABULATED FILE: rr_combined_tabulated.txt ====================================================================== election_title: "Summability demo — Combined (A+B), counted by Ranked Robin" scenario_description: |- The two districts merged, counted by Ranked Robin. These are the SAME ranked ballots IRV could not combine (under IRV, B wins both districts yet is eliminated when merged — see irv_combined). Ranked Robin's pairwise matrix is summable: District A's matrix + District B's matrix EQUALS this combined matrix cell-by-cell, and from it B beats A (11–9) and C (11–9) → B is the Condorcet winner. The candidate who won both districts wins the merge, reached by adding precinct tables, never pooling ballots. voting_method: RankedRobin num_winners: 1 ballots: |- 6:A 4:B 3:C>B>A 6:C 4:B 3:A>B>C expected_winners: - B ====================================================================== TABULATION RESULTS ====================================================================== --- Ranked Robin (RCV-RR / Copeland) Method (single winner) --- Tabulating 26 ballots (ranked ballots). Ballots: 6 × A 8 × B 3 × C > B > A 6 × C 3 × A > B > C Round-Robin — every pair, head-to-head (For – Against): B beats A 11 – 9 A ties C 9 – 9 B beats C 11 – 9 --- Pairwise (Round-Robin) Matrix --- Head-to-head / pairwise comparison — the Ranked Robin tally Legend: For - Equal Support - Against (row vs column) | A | B | C | -------------------------------------------------- A > | --- | 9 - 6 - 11 | 9 - 8 - 9 | B > | 11 - 6 - 9 | --- |11 - 6 - 9 | C > | 9 - 8 - 9 | 9 - 6 - 11 | --- | 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 B 2–0–0 2 +4 A, C 2 A 0–1–1 0.5 -2 — 3 C 0–1–1 0.5 -2 — Winner — Ranked Robin (RCV-RR): B 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 3): B Outside (2): A, C One member ⇒ B is the Condorcet winner, beating every rival head-to-head. Ranked Robin (RCV-RR) winner B 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