Concrete Examples

Concrete Worked Examples & Executable Python Suite

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1. Running the Standalone Python Verifier & Examples

All examples and contract validators live in the standalone normal_forms/ Python package and contracts/ directory:

# 1. Validate all 112 YAML normal form contracts against standard.yaml
python -m normal_forms.catalog

# 2. Run Demo 01: BQNF Incremental Revenue Repair on CDC Events
python -m normal_forms.paid_revenue_example

# 3. Run Demo 02: Unverified Certificate Refusal Gate
python -m normal_forms.unverified_certificate_example

# 4. Run Demo 03: Observer-Relative Freshness SLA Poset Evaluation
python -m normal_forms.observer_freshness_example

# 5. Run Cross-Domain Reconciliation & Loss Ledger Example
python -m normal_forms.reconciliation_example

# 6. Run Demo 05: 4-Hop Composition (3NF/BCNF -> Extrema & Quantile Cochains -> CODA_MUR -> Observer Poset)
python -m normal_forms.multi_hop_composition

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2. Example A: Classical 0NF $\to$ 1NF Flattening & 5NF Consulting Witness (NormalFormsEvaluator)

from normal_forms import NormalFormsEvaluator

with NormalFormsEvaluator() as ev:
    # 1. Flatten repeating CSV groups (0NF -> 1NF)
    rows_1nf = ev.normalize_0nf_to_1nf([
        (1, "Alice", "Math,Physics"),
        (2, "Bob", "Chemistry"),
    ])
    print("1NF rows:", rows_1nf)

    # 2. Check 5NF Project-Join witness (Shell2 EXCEPT Fill2)
    witness = ev.evaluate_5nf_project_join_integrity([
        ("Alice", "Acme", "Widget"),
        ("Alice", "Globex", "Gadget"),
        ("Bob", "Acme", "Gadget"),
        ("Alice", "Acme", "Gadget"),  # closes the 3-way cycle
    ])
    print("5NF witness:", witness)

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3. Example B: 3NF Bernstein Synthesis vs BCNF (normal_forms.domain)

Consider the classic Address(street, city, zip) schema (Date & Darwen's street_journal_title isomorphism) with functional dependencies ${(\text{street}, \text{city}) \to \text{zip},; \text{zip} \to \text{city}}:$

• Candidate keys: ${(\text{street}, \text{city}),; (\text{street}, \text{zip})}$.
• Every attribute (street, city, zip) is prime (belongs to at least one candidate key).
• Therefore, Address passes 3NF ($\text{zip} \to \text{city}$ has a prime dependent city), but fails BCNF because determinant zip is not a superkey!
• Decomposing into $R_1(\text{zip}, \text{city})$ and $R_2(\text{street}, \text{zip})$ achieves BCNF losslessly by Heath's Theorem, while illustrating why BCNF does not always preserve all original functional dependencies within single tables.

from normal_forms.domain import (
    street_journal_title,
    street_journal_title_passes_third_and_fails_boyce_codd,
)

print("Passes 3NF and fails BCNF:", street_journal_title_passes_third_and_fails_boyce_codd())

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4. Example C: BQNF Change Data Capture Incremental Repair (nf.change.bqnf)

Given base relation Orders(order_id, customer_id, status, amount, updated_at) and boundary view:

SELECT customer_id, SUM(amount) AS paid_revenue
FROM Orders
WHERE status = 'paid'
GROUP BY customer_id;

Case	CDC Event	Defect Class in $Q^1$	Terminal Route	Output Repair / Reason
1. Pending $\to$ Paid	old: {status: 'pending', amount: 100} $\to$ new: {status: 'paid', amount: 120}	[0] (Exact Coboundary)	Repair	{customer_id: 7, delta_revenue: +120.0}
2. Paid Amount Update	old: {status: 'paid', amount: 100} $\to$ new: {status: 'paid', amount: 120}	[0] (Exact Coboundary)	Repair	{customer_id: 7, delta_revenue: +20.0}
3. Paid $\to$ Pending	old: {status: 'paid', amount: 100} $\to$ new: {status: 'pending', amount: 100}	[0] (Exact Coboundary)	Repair	{customer_id: 7, delta_revenue: -100.0}
4. Timestamp Only	updated_at changed; status, amount, customer_id unchanged	[0] (Zero Defect)	Preserve	No boundary columns modified
5. Missing Evidence	old / new missing status and amount	[NonZero - MissingEvidence]	Invalidate	Fails closed when CDC before/after image is incomplete
6. Unsupported Extremum	MAX(amount) boundary without auxiliary extremum cochain	[NonZero - LimitOfSubstrate]	Unsupported	Requires priority-queue cochain or partition recomputation

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5. Example D: 4-Hop Composition (3NF/BCNF $\to$ Extrema & $\epsilon$-Quantile Cochains $\to$ CODA_MUR $\to$ Observer Poset)

normal_forms/multi_hop_composition.py chains four normal-form domains end to end:

1. Hop 1 (3NF / BCNF Relational Synthesis): Decomposes Sales(sale_id, customer_id, customer_zip, region, amount, audit_nonce) via Bernstein 3NF synthesis and Tsou-Fischer BCNF tree decomposition, verifying lossless join reconstruction.
2. Hop 2b (Non-Invertible MIN/MAX Priority-Queue Cochains + Dynamic $\epsilon$-BQNF Quantile Sketches over Composite Keys): Streams INSERT/UPDATE/DELETE CDC operations through NormalFormsEvaluator (normal_forms/bqnf_extrema.py, normal_forms/bqnf_repair.py, normal_forms/sales_cochain.py), supporting canonical multi-column composite grouping keys (encode_composite_group_key, e.g., ("region", "channel") or ("region", "channel", "tier")). Repairs destructive MIN/MAX deletions in $O(\log K)$ via region_extremum_cochain (or routes to bounded partition Recompute when disabled) and repairs regional medians within tolerance $\epsilon$ via region_quantile_cochain. When dynamic_buckets=True, rebalance_quantile_cochain recursively bisects overloaded buckets (count > split_threshold) down to min_bucket_width in dense power-law heads and coalesces under-populated dyadic sibling/cousin sub-buckets (combined count <= merge_threshold) bottom-up during stream drains, while verify_quantile_cochain_invariants checks mass conservation, disjoint ordering, and exact point-to-bucket membership.
3. Hop 3 (CODA_MUR Representation Transport nf.coda.mur.transport): Projects across multi-hop target schemas with cryptographically sealed LossLedger bookings (coda_mur.unmapped_field_drop), authenticated target verifiers, and commutation square checks $D_{\text{target}}(F(r)) = \bar{F}(D_{\text{source}}(r))$.
4. Hop 4 (Observer-Relative Freshness Poset nf.epistemic.freshness): Evaluates the transported packet across a stringency-ordered observer poset chain $O_1 \le O_2 \le \dots \le O_m$, checking upward admissibility monotonicity ($O_i \text{ fresh} \implies O_{i+1} \text{ fresh}$) and fail-closed scope/SLA enforcement.

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6. Epistemic Claim Hygiene Quadrant

1. What it supports:
   • Demonstrates in this toy setting that the Python evaluators reproduce the declared terminal routes for 0NF–5NF, BQNF additive and cochain-backed extrema/quantile repair, CODA_MUR representation transport, and observer-relative freshness posets.
2. What it does not support:
   • Does not substitute for production database concurrency control or physical distributed consensus.
3. The narrowest defensible claim:
   • Each worked example and multi-hop property test executes deterministically against the fixtures and randomized schemas in tests/ with AuthorityEffect: None.
4. The next test needed:
   • Concurrent multi-writer transaction interleaving over persistent disk-backed SQLite WAL journals.