arXiv:2606.25954econ.THcs.AI2026-06

证明了严格多数决策在有限框架下无法用有限公理集刻画

Measurable Majorities Are Not Finitely Axiomatizable

  • 通过向量空间正交性构造反例,揭示多数决策的内在不一致性
  • 对任意k,构造出最短不一致序列长度为2k+2的决策框架
  • 解决了一个关于社会决策可公理化的长期猜想,适合逻辑与决策理论研究者

本文研究有限社会决策框架中严格多数推理的有限公理化问题。Moss 和 Pedersen(2026)提出一个一致性准则,精确刻画了定性多数判断可由有限可加测度表示的情形。本文探讨该准则是否可在有限设定下被某个有界有限片段替代。我们证明:不能。对于任意 $k\≥ 1$,构造出一个最大标准框架,其最短一致性破坏长度恰好为 $2k+2$。因此,社会决策框架的不一致指数不存在统一的有限上界,从而解决了 Moss 和 Pedersen(2026)提出的猜想 5.7。构造基于有理数向量空间中的正交性与维度,自包含地分离出对称的半数投票集团,并扩展为排除所有更短平衡矛盾的最大框架。在构造所得的无限宇宙规模序列中,也证实了 Moss 和 Pedersen(2026)猜想 B.25 所预测的中间层族。结合 Moss-Pedersen 严格多数最小逻辑的完备性与可靠性定理,最终确立:可测社会决策框架在该语言下不可有限公理化。

原文摘要 · Abstract (English)

This theoretical note studies the finite axiomatizability of strict majority reasoning in finite social decision frames. Moss and Pedersen (2026) <doi: 10.48550/arXiv.2606.23853> introduce a coherence criterion that characterizes exactly when qualitative majority judgments are representable by a finitely additive measure. The question addressed here is whether that coherence criterion can be replaced, in the finite setting, by any bounded finite fragment. We prove that it cannot. For every $k\ge 1$, we construct a maximal standard frame whose shortest coherence violation has length exactly $2k+2$. Hence there is no uniform finite bound on the incoherence index of social decision frames, resolving Conjecture 5.7 stated by Moss and Pedersen (2026). The construction is geometric, in the sense that it proceeds via orthogonality and dimension in rational vector spaces, and self-contained: it isolates a symmetric family of half-sized voting blocs and extends it to a maximal frame in which every shorter balanced obstruction is excluded. Along the explicit infinite sequence of universe sizes obtained in the construction, this also establishes the middle-layer family predicted by Conjecture B.25 by Moss and Pedersen (2026). Together with the soundness and completeness theorem for the Moss-Pedersen minimal logic for strict majorities, this establishes that measurable social decision frames are not finitely axiomatizable in that language.

逻辑学社会选择公理化

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