D1/D2 Testing Matrix — Cross-Model Usage Evidence

Evidence collected during Phase 2I-4 first compilation run (2026-03-25).

Findings

Element	D1 (Model)	D2 (Type)	Cross-Model Evidence
ax1–ax14	PET	ax	Foundation axioms. Used by JUB (ax15–ax25) as upstream dependencies. ax1 is the root for the entire mereological chain. Cross-model usage is structural: JUB cannot exist without PET.
ax15–ax25	JUB	ax	Extension axioms. Depend on PET ax1–ax14 but are scoped to the JUB model. No reverse dependency (PET does not need JUB). This is a one-directional D1 dependency: JUB → PET.
th5–th11	JUB	th	Theorems in JUB model. Use axioms from both PET and JUB (e.g., th5 depends on ax8, ax9, ax11 from PET and ax15–ax18 from JUB). This is genuine cross-model D1 usage.

Pet Con/Pro Status

Question: Should PET have con/pro fields? Do objections filed under JUB actually target PET axioms?

Status: W (Would be useful)

Evidence: Several JUB quest entries target PET axioms indirectly. For example, critiques of ax19’s uniqueness assumption (Con-C.3) depend on the mereological framework (ax1). The ax11/ax11b fork (dipolarity vs. divine simplicity) is a PET-internal debate that could benefit from formal con/pro tracking within the PET model. Currently, all adversarial review lives in the JUB quest file, even for objections that structurally target PET.

Summary

Cross-model usage is confirmed and structurally important. The JUB model depends on PET as its foundation, and theorems th5–th11 use axioms from both models. PET would benefit from its own con/pro tracking (status W), but the current architecture concentrates all adversarial review in JUB’s quest file.