`liftComposition`🔗

Definition

Lifts a composition of kernels by lifting the inner kernels.

def

liftComposition (e : Lean.Expr) (maxLvl : Lean.Level)
  (proofs : List Lean.Expr) : Lean.MetaM (Lean.Expr × List Lean.Expr)
liftComposition (e : Lean.Expr)
  (maxLvl : Lean.Level)
  (proofs : List Lean.Expr) :
  Lean.MetaM (Lean.Expr × List Lean.Expr)

Code

def liftComposition (e : Expr) (maxLvl : Level) (proofs : List Expr) :
    MetaM (Expr × List Expr) := do
  unless e.isAppOf ``Kernel.comp do
    throwError "Expected a composition of kernels, but got {e}."
  let args := e.getAppArgs
  let η := args[args.size - 2]!
  let κ := args[args.size - 1]!
  let (X, Y, xLvl, yLvl) ← getTypesFromKernel η
  let (Z, _, tLvl, _) ← getTypesFromKernel κ
  let ex ← constructMeasurableEquiv X xLvl maxLvl
  let ey ← constructMeasurableEquiv Y yLvl maxLvl
  let ez ← constructMeasurableEquiv Z tLvl maxLvl
  let comp_lift_proof ← mkAppM ``comp_lift #[ex, ey, ez, η, κ]
  let (η', proofs_η) ← liftExpr η maxLvl proofs
  let (κ', proofs_κ) ← liftExpr κ maxLvl proofs_η
  return (← mkAppM ``Kernel.comp #[η', κ'], comp_lift_proof :: proofs_κ)

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

Audit surface: 5 project declarations, 127 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.

liftComposition🔗

`liftComposition`🔗