election_title: "Successive elimination Ex.12 — truncated: naming only A turns last place into first"
scenario_description: |-
  The TRUNCATED half of Felsenthal's successive-elimination truncation example. Source: Dan S. Felsenthal (2010), Appendix A4, Example 12 — see succ_elim_ex12_sincere.yaml for the sincere profile.
  The same six voters, except the one who sincerely ranked A>B>C>D now names only A. Under the same agenda B vs C, winner vs D, winner vs A: with that voter no longer expressing a B-vs-C preference, round 1 goes to C 3:2 instead of tying; C then beats D 3:2; and the final round ties A against C 3:3, where A survives on the earlier-letter convention. A is elected.
  Sincerely, this voter got D — their last choice. Truncating, they get A — their first. Saying less about the bottom of the ballot was worth three places at the top: the truncation paradox.
  Two honest caveats. The final round is a 3:3 tie, so A's win rests on the earlier-letter convention; under the earlier-on-the-agenda reading C would survive instead, and the paradox would be a smaller one (C rather than D, still an improvement for the truncator, but not their first choice). And the mechanism is specific to procedures that let a ballot sit out a round: the voter is not misrepresenting a preference, only withholding one.
  Labels are Felsenthal's own, capitalized, so the case can be read beside the paper's table.
  Tabulated as Ranked Robin for the pairwise matrix. Run the procedure with tools_adam/pref_voting_tabulation_engine/successive_elimination_report.py --agenda B,C,D,A, and add --tiebreak agenda to see the other reading.
paradoxes: [truncation, condorcet-cycle]
voting_method: RankedRobin
num_winners: 1
ballots: |-
  1:A
  1:C>B>A>D
  2:C>D>B>A
  2:D>A>B>C
expected_winners:
  - C

# file: succ_elim_ex12_truncated.yaml