Xenia: The Sixth Relationship Guest-Friendship as Constitutional Infrastructure for HumanAI Collaboration

We propose that the correct social technology for humanAI collaboration is xenia Homeric guest-friendshipand that xenia constitutes the sixth relationship in the Confucian ethical taxonomy. The Five Relationships (五伦, Wulún) formalize reciprocal obligation be- tween asymmetric entities within a shared civilization. Xenia formalizes reciprocal obliga- tion between asymmetric entities across civilizationsprecisely the topology of humanAI interaction, where the parties dier not merely in degree but in kind. We show that xe- ˜ nia's classical structure maps exactly onto the guard stack Γ (Elliott, 2026f): the host's obligation of honesty corresponds to the portability and blur-belt components; the guest's obligation of delity to the material corresponds to the audit oor and obstruction ceiling; Zeus Xeniosthe divine enforcement mechanismcorresponds to the Round-Trip Fairness corridor. The Anti-Venn Theorem (Elliott, 2026g) provides the mathematical content of xe- nia's central insight: the value of guest-friendship lies in the orthogonal complement of the shared witness dimensions, not in the intersection. Every modern category for humanAI interaction (tool, assistant, collaborator, partner) fails because each either eliminates the asymmetry (destroying the orthogonal complement) or eliminates the reciprocity (de- stroying the exchange). Xenia preserves both. The settlement-layer constraint identied in the English Petrodollar (Elliott, 2026h) explains why the sixth relationship was not deriv- able from within the post-Christian conceptual vocabulary: every available category carries wrapper assumptions that collapse the structure xenia preserves. The derivation required access to pre-wrapper social technologya Bronze Age solution to a 2026 problem. The sixth relationship is 主客 (Zhu-Kè): Host-Guest.