Correspondence Validation¶
Ensure a new model, theory, version, or system matches the old one within the old one’s valid domain before replacing it.
The Diagnostic Story¶
Symptom: A newer model, version, rule, or system is proposed to replace an older one. The replacement is validated on its own terms — it is accurate, well-tested, broadly applicable — but nobody has checked whether it reproduces the older system's trusted behavior in the cases where the old system was already known to work. When the replacement goes live, regressions appear in exactly those cases.
Pivot: Before adopting the replacement, state the predecessor's valid domain explicitly, compare the candidate inside that domain, and classify any divergence as legitimate extension or unacceptable regression. That test governs whether the replacement is adopted as-is, revised, scoped, or rejected.
Resolution: Users and decision-makers retain continuity with trusted behavior in known regimes while the new system extends or modernizes beyond them. Replacement decisions are grounded in a documented overlap test, and regressions inside the predecessor's valid domain are caught before commitment rather than after deployment.
Reach for this when you hear…¶
[regulatory compliance] “The new classification system was more rigorous overall, but it systematically miscategorized a class of cases that the old system had handled correctly for a decade.”
[software version migration] “The rewritten API was cleaner, but the team only tested new use cases — nobody checked that the old integrations still worked until the migration was live.”
[clinical guidelines] “The updated protocol improved outcomes on average, but it produced worse outcomes for the specific population the old guideline was designed for.”
When This Archetype Applies¶
No catalog groundingNone of the structural conditions is currently represented by an accepted prime or domain-specific abstraction.
Diagnostic problem
A proposed successor may fail to preserve behavior that was already relied upon within the predecessor's established domain.
What this problem means
The structural problem is replacement under incomplete continuity. A new system may be better overall, more modern, more general, or more efficient, yet still fail in cases where the old system was reliable. Because attention is often drawn toward the new capability, old-domain regressions may remain hidden until users, dependent systems, or high-stakes cases encounter them.
This problem is common when old systems are messy but valuable. They may contain tacit knowledge, edge-case handling, compatibility promises, historical conventions, or user expectations that were never fully documented. When the replacement is evaluated only on new goals, the hidden value of old behavior can disappear.
Show the applicability expression
Applicability expression2 distinct conditions
groundedpartly groundedopen
2 conditions, all required.
2Required in every casenumbered 1–2
These hold no matter which pattern applies.
Trusted predecessor domain · open
The predecessor has an established domain in which its behavior is relied upon.
This proposition-sized condition was conservatively reconstructed from the authored trigger_conditions, structural_problem fields; the source file was not modified. In this condition set, the requirement is: The predecessor has an established domain in which its behavior is relied upon.
Comparable overlap domain · open
An overlap domain permits meaningful comparison of predecessor and successor behavior.
This proposition-sized condition was conservatively reconstructed from the authored trigger_conditions, structural_problem fields; the source file was not modified. In this condition set, the requirement is: An overlap domain permits meaningful comparison of predecessor and successor behavior.
Other requirements and context (3)
Why these sit outside the expression
Supporting context — it may accompany or help interpret the situation, but it is not a load-bearing condition in a sufficient diagnostic set.
Application gate — it governs whether applying the archetype is appropriate or material, rather than defining the structural problem itself.
Supporting contextA new model, rule, version, workflow, policy, or system is proposed as a successor to an existing one.
This proposition-sized condition was conservatively reconstructed from the authored trigger_conditions, structural_problem fields; the source file was not modified. In this archetype, the relevant contextual consideration is: A new model, rule, version, workflow, policy, or system is proposed as a successor to an existing one. It helps interpret the situation or strengthens the practical case for examining the archetype.
Application gateRegression in the established domain would impose material continuity, safety, trust, compliance, or operational cost.
This proposition-sized condition was conservatively reconstructed from the authored trigger_conditions, structural_problem fields; the source file was not modified. In this archetype, the relevant application gate is: Regression in the established domain would impose material continuity, safety, trust, compliance, or operational cost. It narrows when choosing or applying the archetype is warranted or decision-relevant.
Supporting contextAdvantages in new cases may conceal breakage in old cases.
This proposition-sized condition was conservatively reconstructed from the authored trigger_conditions, structural_problem fields; the source file was not modified. In this archetype, the relevant contextual consideration is: Advantages in new cases may conceal breakage in old cases. It helps interpret the situation or strengthens the practical case for examining the archetype.
Coverage
0 of 2 conditions grounded · 2 open.
Mechanisms / Implementations¶
- Backward Compatibility Test: Checks that a new version still honors every promise existing consumers already rely on, so an internal change can ship without breaking anyone downstream.
- Divergence Review Workflow: Routes each already-detected old-versus-new mismatch through a standing triage that classifies it, logs the accepted exceptions, and records the disposition — so differences are governed, not quietly ignored.
- Golden Case Benchmark: A curated library of canonical input-to-output cases, captured from the current system, that serves as the fixed reference for judging whether a refactor changed observable behavior.
- Migration Acceptance Test: Uses agreed acceptance criteria to decide whether a migration may proceed, pause, roll back, or remain limited to a subset of cases.
- Model-Limit Validation: Checks whether a newer or more general model reduces to, approximates, or preserves the trusted older model under the older model's limiting conditions.
- Protocol Conformance Test: Verifies that a new implementation still satisfies old interface, format, or protocol obligations within the claimed compatibility domain.
- Regression Test Suite: Re-runs a corpus of previously-passing cases against each new version so that any unintended loss of working behaviour breaks the build, using the system's own recorded past output as the reference.
- Shadow Run or Parallel Run: Runs the new implementation alongside the old on live traffic — old system serving, new system shadowing — and compares their outputs and real-world side effects before trusting the new one to take over.
Related Abstractions¶
Abstractions this archetype builds on — directly (a source ingredient) or as a related pattern. Links follow the typed catalog namespace.
Built directly on (2)
- Correspondence Principle: New theories match old limits.
- Versioning: Tracks incremental changes over time.
Also references 9 related abstractions
- Boundary: Defines system limits.
- Continuity: Smooth change without jumps.
- Data Integrity: Accuracy and consistency preserved.
- Interoperability: Systems function together.
- Invariance: Properties unchanged under transformation.
- Ontology: What exists and how entities relate.
- Relation: Describes associations or dependencies.
- Schema: Structured knowledge framework.
- Stationarity: Stable statistical properties.
Variants¶
Narrower or domain-specific specializations that share this archetype's core structure. Recognized variants are established; candidate variants are provisional.
Backward Compatibility Validation · implementation variant · recognized
Validate that a new version preserves existing behavior, interfaces, or user expectations where old compatibility is still promised.
Model-Limit Correspondence · subtype · recognized
Validate that a newer or broader model reproduces the older model under the older model’s domain of validity or limiting conditions.
Migration Correspondence Validation · temporal variant · recognized
Validate old-new continuity during a migration so users, data, obligations, and operational behavior survive the transition.
Editorial Notes¶
Problem Classification¶
Classification: Correctness, Conformance & Formal Validity Failure → Mapping, Rewrite & Structure Preservation
Problem kernel: a replacement may not preserve trusted prior cases
Rationale: The newer model claims succession but lacks correspondence evidence that known regimes, behaviors, and obligations survive the mapping.
Independent corroboration: The earliest necessary condition in the frozen evidence is: A newer model, rule, version, workflow, policy, or system is proposed as a replacement for an older one, but it may fail in the very cases where the older system was already trusted. That is a mapping rewrite and structure preservation problem because Translation, replacement, inversion, lowering, or transformation changes meaning, reachability, connectivity, correspondence, or invariants that were required to survive.
Review outcome: Independent reviewer agreement; high confidence.