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The system of record for formal trust.

Lemryn shows what changed in a proof, which assumptions moved, what else depends on it, and which verifiers already ran.

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Pull request 84
payment_is_conserved
StatementUnchanged
ProofChanged
Dependencies+ 1 − 1
AxiomIntroduced
SorryNone in this theorem
Fig. 1 — A pull request, read as a proof
Workflow

From a diff to a decision.

  1. 01
    A pull request opens

    Base and head Lean sources are read. Lake checkouts are left out.

  2. 02
    Declarations are compared

    Statement hashes, proof hashes, axioms, and sorry usage.

  3. 03
    Reachability is traced

    Declarations that mention the change, then the ones that mention those.

  4. 04
    A decision is recorded

    Checks passed, review required, or blocked. One comment stays on the pull request.

Before
  • Classical.choice
  • —
After
  • Classical.choice
  • + custom_payment_axiom
Fig. 2 — The trust boundary
transaction_nonnegativepayment_validsettlement_validaccounting_correct
Fig. 3 — Downstream reachability
Review required
  • New axiom introduced
  • Theorem statement changed
  • 6 downstream declarations
  • Lean KernelPass
  • nanodaPass
  • ComparatorNot run
Fig. 4 — The merge decision
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