`checkAssociator`🔗

Definition

Check if a kernel expression corresponds to an associator morphism or its inverse.

def

checkAssociator (κ : Lean.Expr) (hom : Bool) : Lean.MetaM Bool
checkAssociator (κ : Lean.Expr)
  (hom : Bool) : Lean.MetaM Bool

Code

def checkAssociator (κ : Expr) (hom : Bool) : MetaM Bool := do
  let κ := κ.consumeMData
  if !κ.isAppOf ``Kernel.deterministic then
    return false
  let args := κ.getAppArgs
  let fn := args[args.size - 2]!
  if !fn.isAppOf ``DFunLike.coe then
    return false
  let fn := fn.getAppArgs[fn.getAppApps.size - 1]!
  if hom then
    if !fn.isAppOf ``MeasurableEquiv.prodAssoc then
      return false
  else
    if !fn.isAppOf ``MeasurableEquiv.symm then
      return false
    let innerFn := fn.getAppArgs[fn.getAppArgs.size - 1]!
    if !innerFn.isAppOf ``MeasurableEquiv.prodAssoc then
      return false
  return true

Actions: Source · Open Issue

Meaning last changed in v4.34.0-rc2-1-g439785b (2026-08-23).

Self-contained, with its dependencies inlined and proofs replaced by sorry: download the raw file · open it in the Lean web editor.

Dependency graph

Nothing to draw. Its statement rests on no other declaration in this project, and names nothing from a package left unaudited — so the graph is this declaration alone. That is the answer, not a missing picture.

Audit surface: 0 project declarations, 40 external constants

✓ Proved: no sorry anywhere in its closure

This is the tool's own reading of one build's recorded axioms, and it is not robust against an author who wants it to pass. Checking meant to be relied on should go through Comparator, which replays the proof through the kernel from an export against an explicit list of permitted axioms.

checkAssociator🔗

`checkAssociator`🔗