# One Derivation

> One canonical question has one authoritative derivation

Record: `reasoning:invariant-epi-one-derivation`
Kind: invariant
Canonical: https://banes-lab.com/ontology/reasoning#reasoning-invariant-epi-one-derivation

Listed in [Reasoning records](https://banes-lab.com/api/records/reasoning.md), after [Fresh Read](https://banes-lab.com/records/reasoning/invariant-epi-fresh-read.md) and before [Weakest Link](https://banes-lab.com/records/reasoning/invariant-epi-weakest-link.md).

## Grounded by

- [COPY](https://banes-lab.com/records/pag/keyword-action-copy.md)

## Linked from

- [Definitions own what, code owns how](https://banes-lab.com/software-architecture/model/definitions-own-what.md)
- [The canon is grouped twice](https://banes-lab.com/software-architecture/principles/the-canon-is-grouped-twice.md)
- [Failure shapes](https://banes-lab.com/ontology/reasoning/the-failure-shapes.md)
- [action](https://banes-lab.com/ontology/grammar/pag-keywords-action.md)