Mixle Core scientific validity

Document ID: CORE-DOC-SCIENTIFIC-VALIDITY-001 Version scope: 0.8.x development Owner: PRJ-CORE

Core supplies scientific computing primitives; it does not make every model scientifically valid by construction. Validity depends on the formulation, data, assumptions, inference route, diagnostics, and decision context.

Required assumptions

Record units, domains, coordinate conventions, data-generating and missingness assumptions, likelihood and prior choices, known and unknown quantities, identifiability limits, numerical precision, and excluded effects.

Invariants

Applicable checks include finite canonical quantities, normalized probabilities, support behavior, covariance symmetry and positive semidefiniteness, deterministic seeded behavior, conservation or symmetry where modeled, monotone objective behavior where promised, calibrated coverage, and explicit failure on unsupported operations.

Verification and validation

Prefer analytic invariants and manufactured examples, then trusted reference solutions, independent implementations, controlled data, and expert review. Shared code or assumptions do not provide independent corroboration.

Validation data used to choose a model is not independent confirmation. Empirical law discovery, calibration, and model comparison must keep selection and confirmation roles explicit.

Uncertainty and limits

Report aleatoric, epistemic, measurement, model-discrepancy, and numerical uncertainty when applicable. A calibrated result is valid only for the tested population, model, data regime, and operating conditions. Low-power tests, non-identifiability, distribution shift, extrapolation, and optional-backend differences remain visible limitations.

Reproducibility

Record source revision, environment, dependencies, inputs or digests, configuration, seeds, precision, backend, stopping criteria, commands, outputs, and tolerances. Portable hashes must not depend on process-randomized runtime behavior.

The detailed numerical stability contract is in stability-and-missing-data.rst. Release-critical scientific claims require the evidence level declared by their status requirement.