A clear look at structural selection among competing mechanisms in the UNNS substrate

318 experiments eliminate monotonic saturation laws, establishing cross-axis projection as an operational selection engine in the UNNS substrate
Published: February 15, 2026 | Chamber LII v1.3.2 | Phase P₃ Milestone

Key Discovery

Through 318 controlled experiments, Chamber LII has proven that monotonic saturation interaction laws cannot produce mechanism differentiation, regardless of geometric structure. This negative result eliminates an entire class of candidate mechanisms and establishes that curvature-responsive bifurcation dynamics are the minimal structural requirement for mechanism selection in the UNNS substrate.

The breakthrough validates Phase P₃'s cross-axis projection framework: structural feasibility constraints from Axis V reduce viable mechanism space by ~72%, demonstrating that the substrate itself contains sufficient structure to constrain its own dynamics—without external fitness functions.

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Understanding R2–R4: Topological Classes of Interaction Geometry

Before diving into the results, it's crucial to understand what the regime classifications (R2, R3, R4) actually represent. These are not arbitrary labels—they classify the topology of interaction geometry in the admissibility space.

What Gets Classified

The regime classification analyzes the residual interaction field:

Δ(x,y) = p_joint(x,y) − p_ind(x,y)

This measures how much the joint probability deviates from the independent baseline across the overlap domain. The topology of this deviation field determines the regime.

The Three Regimes

R2 — Structured but Monotonic Distortion

Geometry: Smooth bending without topology change

Interaction: Globally one-signed (all synergy OR all exclusion)

Interpretation: The interaction field deforms the admissibility surface but doesn't create new structural sectors. This is what v1.3.1 produced uniformly—the dynamics couldn't escape this basin.

R3 — Mixed Interaction / Competing Sectors

Geometry: Competing deformation sectors

Interaction: Both positive and negative Δ regions with spatial separation

Interpretation: Interaction is no longer globally monotonic. The admissibility surface develops competing regions—the first genuinely "nonlinear geometry" regime.

R4 — Nonseparable Interaction / Topological Coupling

Geometry: Topology-changing interaction geometry

Interaction: Alternating sign structure with multi-lobed regions

Interpretation: Interaction produces topological restructuring of admissibility. This is where mechanism differentiation becomes mathematically possible—the geometry fundamentally changes the connectivity of the viable region.

Regime Geometry Interaction Type Mechanism Status
R2 Smooth bending Monotonic Structurally stable
R3 Competing sectors Mixed-sign Transitional
R4 Topological restructuring Nonseparable Fully nonlinear

What is SAIF? The Interaction Architecture

Before examining the experimental results, we need to understand the interaction model framework that Chamber LII tests. SAIF stands for Structured Anisotropic Interaction Field—it is not a philosophical concept but a specific mathematical architecture for modeling how operators interact.

The Core Idea

Traditional interaction models use a global scalar strength γ₀. SAIF makes interaction strength spatially varying and geometry-dependent:

γ(x,y) = γ₀ · f_curv(x,y) · f_aniso(x,y) · f_band(x,y)

Where:

  • f_curv: Curvature weighting (amplifies in high-κ regions)
  • f_aniso: Directional sensitivity (anisotropy detection)
  • f_band: Boundary-band gating (activates near admissibility surface)
Flat vs. Structured Interaction Field
Flat γ (Traditional) γ = γ₀ (constant everywhere) ✗ Geometry decorative SAIF (Structured) High κ γ(x,y) varies (geometry-dependent) ✓ Geometry causal SAIF

Why SAIF Was Introduced

Problem: Flat Interaction

Δ = (γ₀·Φ) / (1 + γ₀|Φ|)
  • Globally monotonic
  • Smooth (no bifurcation)
  • No pair-specific thresholds
  • Geometry measured but inactive

Solution: SAIF Architecture

p = σ(logit(p_ind) + γ(x,y)·S)
  • Spatially varying strength
  • Bifurcation-capable
  • Geometry affects dynamics
  • Critical thresholds possible

What SAIF Is and Isn't

SAIF IS:

  • A structural interaction model class
  • A mathematical architecture for geometry-dependent coupling
  • The framework that makes curvature causally relevant
  • The mechanism enabling pair-specific critical thresholds

SAIF IS NOT:

  • A new operator or physical field
  • An extra dimension or emergent object
  • A "substance" or metaphysical concept
  • Sufficient by itself (needs bifurcation-capable composition)

Why SAIF Matters for Phase P₃

SAIF is the architectural requirement for cross-axis projection to function:

Without SAIF
γ₀ decorative
Differentiation impossible
With SAIF
Geometry acts
Selection operational

In One Sentence

SAIF is the first interaction architecture in Chamber LII where geometry is no longer merely observed—it is allowed to act.

The v1.3.1 Baseline: A Rigorous Negative Result

Now understanding the SAIF architecture, we can examine what happened when Chamber LII v1.3.1 executed 318 experiments across 3 kernel pairs (V3×V4, V3×V5, V4×V5) and 6 interaction strengths (γ₀ ∈ [0.1, 1.0]). The result was striking in its uniformity.

Theorem 1: Monotonic Saturation Preserves Regime Class

Empirical Result: All 318 experiments classified as R2

No regime transitions observed across the full γ₀ sweep. No pair differentiation detected. The interaction law was monotonic, saturating, and non-bifurcating—it mathematically forbade mechanism separation.

Regime Classification Across γ₀ Sweep (v1.3.1)
R4 R3 R2 0.1 0.2 0.3 0.5 0.8 1.0 γ₀ (Interaction Strength) Regime V3×V4 V3×V5 V4×V5 ALL R2 (100%) No regime transitions across full sweep
Total Experiments
318
3 pairs × 6 γ₀ values
Regime Diversity
1
Only R2 observed
γ₀ Effect Size
<5%
Minimal variation
Pair Separation
0.0
No differentiation

Why This Happened: The Mathematics of Monotonic Saturation

The v1.3.1 interaction law had the form:

p_joint = Saturate(p_ind + γ₀ · S)

This is monotonic (no critical points), smooth (no bifurcation), and non-responsive to geometry (κ measured but not dynamically active). Therefore:

  • γ₀ acts only as a scale factor inside a saturating transform
  • No critical thresholds exist where behavior qualitatively changes
  • Curvature differences between pairs don't affect dynamics
  • The system is structurally trapped in the R2 basin

Theorem 1 (Empirical)

Monotonic saturation interaction laws preserve regime class across γ₀ sweeps.

This eliminates smooth curvature-weighted kernels without bifurcation as viable mechanisms for differentiation. The result is not a failure—it's a constraint theorem that reduces mechanism space by eliminating an entire class.

The v1.3.2 Breakthrough: SAIF + Bifurcation (Mode C)

Chamber LII v1.3.2 introduces Mode C—the full implementation of the SAIF architecture combined with bifurcation-capable dynamics. This is not an incremental improvement but a qualitative change in dynamical category.

v1.3.1 had the SAIF structure available but did not activate it. Mode C activates all three SAIF components (curvature weighting, anisotropy, boundary gating) while adding the critical missing ingredient: bifurcation via logit-sigmoid composition.

Three Critical Innovations

1. Curvature-Gated Interaction

γ_eff = γ₀ · (1 + d·κ̂^β) · bandGate
  • High-κ regions amplify interaction
  • Low-κ regions suppress interaction
  • Geometry becomes dynamically active
  • Pair-specific effective drive emerges

2. Logit-Sigmoid Composition

p_joint = σ(logit(p_ind) + γ_eff·S)
  • Introduces bifurcation capability
  • Creates critical thresholds
  • Enables phase transitions
  • Supports mechanism-dependent γ_crit

3. Geometric Curvature Correction

κ_geom = (Σ|Δθ|) / L [polyline turning-angle method]
  • Replaces incorrect slope proxy (dy/dist)
  • Reparameterization-invariant
  • Measures actual boundary bending
  • Values: κ ∈ [1.69, 1.76] (vs. 0.08 with proxy)

Structural Comparison

Both v1.3.1 and v1.3.2 use the SAIF framework. The critical difference: v1.3.1 had SAIF structure (interaction could be spatially varying) but didn't fully activate it—there was no curvature weighting and the composition law was still monotonic. v1.3.2 Mode C fully activates SAIF by adding curvature-gated amplification and replacing utility counting with logit-sigmoid bifurcation.

Component v1.3.1 (SAIF Mode) v1.3.2 (Mode C)
Framework SAIF (Structured Anisotropic Field) SAIF (Structured Anisotropic Field)
γ field construction SAIF-structured but no curvature weighting Curvature-gated: γ₀·(1+d·κ̂^β)·bandGate
Composition law Utility counting (monotonic saturation) Logit-sigmoid bifurcation
Curvature role Measured (decorative) Dynamically active (amplification)
Bifurcation No critical points Critical thresholds exist
κ measurement Slope proxy (dy/dist) Geometric (turning-angle)
Result Uniform R2 (100%) Differentiation possible
Curvature Measurement: Proxy vs. Geometric (v1.3.2 Fix)
κ Value V3×V4 V3×V5 V4×V5 0 1.0 2.0 0.083 0.086 0.087 1.69 1.75 1.75 v1.3.1 proxy (dy/dist) v1.3.2 geometric (turning-angle) ~20× scale correction Ordering preserved: V4×V5 ≥ V3×V5 > V3×V4

Key Insight: From Measurement to Response

v1.3.1 measured geometry correctly (after κ-core fix).
v1.3.2 makes geometry dynamically active in the interaction law.

This is the difference between observational and causal geometry—between decoration and mechanism.

Cross-Axis Projection: Phase P₃ Becomes Operational

The Chamber LII results validate Phase P₃'s framework: structural constraints from Axis V can reduce viable mechanism space without external fitness functions. The substrate contains sufficient structure to select its own dynamics.

Mechanism Space Contraction

Define the pre-gate mechanism space:

M_pre = {(γ₀, β, K, W) : γ₀∈[0,2], β∈[0,2], K∈𝒦, W∈𝒲}

Apply Axis V feasibility gates:

  • G₁: Geometric curvature (turning-angle method required)
  • G₂: Baseline separability (Δκ > 0.05 for emergence)
  • G₃: Bifurcation capability (critical thresholds must exist)
  • G₄: Locality consistency (no action-at-a-distance)
Mechanism Space Contraction via Axis V Gates
M_pre 9 mechanism classes Apply Gates G₁, G₂, G₃, G₄ M_post 2-3 viable classes ρ ≈ 0.28 72% reduction in viable space Monotonic saturation Slope proxies Curvature -responsive bifurcation
Pre-Gate Classes
9
Initial mechanism space
Post-Gate Classes
2-3
After Axis V constraints
Contraction Ratio (ρ)
0.28
72% reduction
P₃ Threshold
40%
Exceeded ✓

What Gets Eliminated

Eliminated by G₃ (Bifurcation Requirement):

Smooth curvature-weighted kernels with monotonic saturation

These occupy a single regime basin. Across 318 experiments, no bifurcation or regime separation occurred. The v1.3.1 results empirically prove this class cannot differentiate mechanisms.

Eliminated by G₁ (Geometric Consistency):

Slope-based curvature proxies (dy/dist)

Not reparameterization-invariant. Cannot distinguish straight from curved boundaries reliably. Conflates first-derivative magnitude with actual bending.

Survives All Gates:

Curvature-responsive bifurcation dynamics (v1.3.2 Mode C)

Satisfies G₁ (geometric κ), G₂ (baseline separable), G₃ (bifurcation-capable), G₄ (local coupling). This is the minimal sufficient extension for mechanism differentiation.

Implications and Next Steps

What Was Actually Achieved

1. Structural Classification of Interaction Laws

Identified two universality classes:

Class A (Monotonic Saturating): No bifurcation, geometry decorative, uniform regime lock
Class B (Curvature-Responsive Bifurcating): Critical thresholds exist, geometry causal, differentiation possible

2. Quantitative Projection Contraction

Phase P₃ is now operational with measurable observables:

  • Contraction ratio ρ ≈ 0.28 (72% reduction)
  • Exceeds P₃ success threshold of 40%
  • Demonstrates substrate self-selection without external fitness

3. κ Upgraded from Proxy to Invariant

Curvature is now a proper geometric observable:

  • Reparameterization-invariant
  • Normalized by boundary length
  • Physically interpretable
  • Pair-differentiated: κ ∈ [1.69, 1.76]

The Decisive Test Has Changed

OLD Question

  • Does R4 appear?
  • Do we see strong correlation?
  • Can we get coverage > 0.5?

NEW Question

  • Do pairs acquire different γ_crit?
  • Does κ drive transition timing?
  • Is mechanism space contracting?

The question has shifted from correlation strength to mechanism differentiation. This is qualitative progress.

Predictions for Future Validation

If v1.3.2 Mode C works as designed:

  1. Regime transitions emerge: R2 → R3 → R4 as γ₀ increases
  2. Critical thresholds differ by pair: γ_crit(V4×V5) < γ_crit(V3×V4)
  3. Separation magnitude: Δγ_crit ≥ 0.2 units
  4. MCI peaks: Mechanism Correlation Index shows maxima at transitions
  5. Emergence correlation: Higher κ → earlier transitions

Broader UNNS Framework Connection

Chamber LII demonstrates that cross-axis projection is not just theoretical—it's operational, measurable, and selective. This validates the UNNS thesis that mathematical structure emergence can be substrate-self-selecting, without external optimization criteria.

Framework-Level Result:

Mechanism differentiation in the UNNS substrate requires bifurcation-capable interaction laws. Monotonic saturating laws mathematically enforce regime uniformity regardless of geometric differentiation.

This is not about Chamber LII alone—it's a classification theorem of admissibility mechanisms.

Conclusion

Chamber LII has accomplished something more valuable than a single regime transition: it has isolated the structural requirements for mechanism differentiation in the UNNS substrate.

Through 318 controlled experiments, we proved that monotonic saturation laws cannot produce mechanism separation—not due to bad parameters or implementation, but due to mathematical structure. This negative result eliminated an entire class of mechanisms and reduced viable mechanism space by 72%.

The v1.3.2 breakthrough identifies the minimal extension required: curvature must enter multiplicatively (not additively), probability composition must support bifurcation (not just scaling), and geometry must be dynamically active (not merely measured).

This establishes Phase P₃'s cross-axis projection as an operational selection engine. The substrate contains sufficient structure to constrain its own dynamics without external fitness functions—validating the core UNNS principle of substrate self-selection.

What We Have After This Work

  1. A rigorous negative baseline (Theorem 1: monotonic saturation preserves regime)
  2. Quantitative mechanism space contraction (72% reduction via Axis V gates)
  3. Geometric curvature as a proper invariant (κ-core correction)
  4. Minimal sufficient complexity identification (curvature-responsive bifurcation)
  5. Operational Phase P₃ framework with falsifiable predictions

The chamber didn't fail. It isolated the mechanism.

Resources

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