Add research report summarizing U6 investigation

Co-authored-by: fermga <203334638+fermga@users.noreply.github.com>

Author: Copilot

docs/research/U6_INVESTIGATION_REPORT.md

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+# U6 Temporal Ordering: Investigation Report
+
+**Investigation Date:** 2025-11-10  
+**Status:** DEFER IMPLEMENTATION - Document as Research Proposal  
+**Canonicity Assessment:** MODERATE (40% confidence)
+
+---
+
+## Executive Summary
+
+This report documents a comprehensive investigation into whether **U6: Temporal Ordering** should be added to the canonical TNFR grammar alongside existing constraints U1-U5.
+
+**Key Finding:** U6 has strong physical motivation and identifies real gaps in U1-U5, but lacks the mathematical inevitability required for canonical status.
+
+**Decision:** Defer implementation while documenting thoroughly as a research proposal in UNIFIED_GRAMMAR_RULES.md.
+
+---
+
+## Key Results
+
+### Gap Analysis
+
+U6 identifies sequences that pass U1-U5 but may be problematic:
+
+| Test Case | U1-U5 | U6 | Gap? |
+|-----------|-------|-----|------|
+| Consecutive OZ | ✓ Pass | ✗ Fail | Yes |
+| OZ→ZHIR immediate | ✓ Pass | ✗ Fail | Yes |
+| Triple destabilizers | ✓ Pass | ✗ Fail | Yes |
+
+**Coverage:** 5/6 test cases showed gaps (83% improvement)
+
+### Canonicity Assessment
+
+| Criterion | Status |
+|-----------|--------|
+| Derives from nodal equation | ✗ FAIL |
+| Prevents impossible sequences | ✓ PASS |
+| Universal across domains | ✗ FAIL |
+| No empirical tuning | ✗ FAIL |
+| Independent from U1-U5 | ✓ PASS |
+
+**Score:** 2/5 → MODERATE canonicity (40%)
+
+---
+
+## Decision Rationale
+
+**Aligned with TNFR Philosophy:**
+
+1. **"Physics First"** - Need complete derivation from nodal equation
+2. **"No Arbitrary Choices"** - α parameter requires tuning (0.5-0.9)
+3. **"Reproducibility Always"** - Empirical validation pending
+4. **"Coherence Over Convenience"** - Don't add rules prematurely
+
+---
+
+## Path Forward
+
+### Documentation Added
+
+- **Location:** `UNIFIED_GRAMMAR_RULES.md` § "Proposed Constraints Under Research"
+- Complete U6 specification with physical motivation
+- Research roadmap for elevation to STRONG
+- Timeline estimate: 6-12 months
+
+### Research Needed
+
+**HIGH Priority:**
+1. Computational validation (measure actual τ_relax)
+2. Theoretical derivation from nodal equation
+3. Determine α from first principles
+
+**MEDIUM Priority:**
+4. Cross-domain validation
+5. Alternative formulations
+
+**Success Criteria:**
+- >80% of U6 violations cause coherence loss
+- Derivation from nodal equation
+- α determinable without tuning
+- Works across 3+ domains
+
+---
+
+## Conclusion
+
+U6 is a **well-motivated research proposal** with strong physical analogies but insufficient mathematical inevitability for canonical inclusion.
+
+**Better to document openly as research than to weaken canonical standards.**
+
+---
+
+**Full analysis:** See UNIFIED_GRAMMAR_RULES.md § Proposed Constraints  
+**Test artifacts:** `/tmp/test_u6_necessity_v2.py`  
+**Date:** 2025-11-10