Strategyproof Social Decision Schemes on Super Condorcet Domains

· AAMAS 2023 (p17)

no mirror
paperStrategyproof Social Decision Schemes on Super Condorcet Domains
authors
venueAAMAS 2023
filed undervoting · probabilistic
judged bygpt-5.6-terra / high (triple__gpt-5.6-terra__high__ctx2r8-rejudge1)
judge confidencehigh
authors would recognise itunclear

Why no mirror

The paper contains no numbered theorem, lemma, or corollary asserting computational hardness, tractability, approximation, or parameterized complexity. Its named results are axiomatic characterizations of social decision schemes over finite named-voter profiles. The proposed mass-manipulation model is an interesting independent extension, but it does not repair the missing computational anchor.

fails bit a — no named computational result to mirror

What the mirror covers

The proposed continuum discussion parallels the paper's Condorcet-domain and strategyproofness themes, but no named computational result is covered.

The case FOR (proponent)

There is no named computational result in this paper to anchor a ChoCo mirror. Theorem 1, Theorem 2, and Theorem 3 are axiomatic characterizations of strategyproof SDSs; Lemmas 1–3 are structural ingredients. None asserts NP-hardness, membership in P, FPT, approximation, or another computational classification. On the stated anchoring rule, that is a complete reason not to claim a paper-derived continuization result.

The closest continuous object is nevertheless clear: an anonymous society is a distribution \(\mu\) over rankings, restricted to the open Condorcet region
\[ \{\mu:\exists c\;\forall d\ne c,\ \mu(\{t:c\succ_t d\})>1/2\}. \]
A social decision scheme maps such a \(\mu\) to a lottery. A coalition is a positive mass of true ranking-types, with a feasible report-transfer matrix moving that mass to reported types; one could ask whether a prescribed rule, such as the Condorcet rule, admits a beneficial mass manipulation while both truthful and reported societies remain in the Condorcet region.

But this is an axiomatic continuum analogue, not yet the programme’s computational question. More importantly, the paper’s central characterizations rely on named voters and on random dictatorships—objects that do not survive an anonymous high-multiplicity representation without a substantive redesign. Infinitesimal individual strategyproofness becomes vacuous, while positive-mass coalition strategyproofness is a different condition and would need fresh theorems.

So the honest positive verdict is modest: the Condorcet-region geometry gives a plausible starting point for a future continuous manipulation/verification problem, especially for mass coalitions. This paper itself, however, supplies no named computational anchor and should not be presented as a substantive ChoCo mirror.

The case AGAINST (opponent, writing after the proponent)

The negative case is decisive at the required anchoring level: this paper contains no named computational result. Its theorems characterize which SDSs satisfy strategyproofness, group-strategyproofness, and non-imposition on particular profile domains. They do not classify a computational problem or provide an algorithmic task to continuize. ChoCo is about computational questions over a continuous population, not an axiomatic restatement over one.

The proponent’s proposed object does not cure that gap. Replacing a profile by a distribution over rankings and the Condorcet domain by its open majority region is a natural piece of voting geometry, but it is precisely an axiomatic continuum analogue. The paper’s notion of strategyproofness is indexed by a named voter’s unilateral report, and its random dictatorships assign probability to named voters. In an anonymous mass society, an individual has zero mass; retaining unilateral strategyproofness is vacuous. Replacing it with profitable deviations by a positive mass of types is a substantive new model of coordinated reporting, not a high-multiplicity version of the paper’s object.

One can certainly invent a computational problem for that new model—specify a rule, admissible transfer matrices, coalition objectives, and an encoding—but none of those ingredients is selected by the paper’s results. Different choices produce genuinely different questions: whether all mass of a type must coordinate, whether a coalition may split a type, which members’ stochastic-dominance interests constrain a coalition, and whether reports must remain in the Condorcet region. The paper supplies no computational claim that privileges one formulation over the others.

Thus the proposed “mass manipulation” direction may be a reasonable independent project in continuous voting, but it is not a worthwhile ChoCo mirror *of this paper*. The honest negative case is strongest not because continuous Condorcet societies are meaningless, but because this is an axiomatic characterization paper with no computational anchor from which the programme’s complexity landscape can begin.

The adversarial triple: the proponent anchors on up to three named results; the opponent sees that case and must defeat every anchor; the judge decides which case convinced it. These are the pipeline’s own outputs, generated by tools/triple_run.py — no human edited them. The paper’s own text is not reproduced here beyond the quoted statement above.