ProbabilityTheory.Kernel.sigma
From the authors
The kernel on Σ a, β a which is κ a on the fiber β a.
-
α : Type u_1 -
γ : Type u_2mγ : MeasurableSpace γA measurable space is a space equipped with a σ-algebra.
-
β : α → Type u_3(a : α) → MeasurableSpace (β a) -
κ : (a : α) → Kernel (β a) γA kernel from a measurable spaceαto another measurable spaceβis a measurable functionκ : α → Measure β.
Kernel ((a : α) × β a) γ{ toFun := fun x => (κ x.fst) x.snd, measurable' := ⋯ }MeasurableSpace : Type u_6 → Type u_6A measurable space is a space equipped with a σ-algebra.
ProbabilityTheory.Kernel : (α : Type u_1) → (β : Type u_2) → [MeasurableSpace α] → [MeasurableSpace β] → Type (max u_1 u_2)A kernel from a measurable space `α` to another measurable space `β` is a measurable function `κ : α → Measure β`. The measurable space structure on `MeasureTheory.Measure β` is given by `MeasureTheory.Measure.instMeasurableSpace`. A map `κ : α → MeasureTheory.Measure β` is measurable iff `∀ s : Set β, MeasurableSet s → Measurable (fun a ↦ κ a s)`.
ProbabilityTheory.Kernel.mk : {α : Type u_1} →
{β : Type u_2} →
[inst : MeasurableSpace α] →
[inst_1 : MeasurableSpace β] →
(toFun : α → MeasureTheory.Measure β) → Measurable toFun → ProbabilityTheory.Kernel α βSigma.fst : {α : Type u} → {β : α → Type v} → Sigma β → αThe first component of a dependent pair.
Sigma.snd : {α : Type u} → {β : α → Type v} → (self : Sigma β) → β self.fstThe second component of a dependent pair. Its type depends on the first component.
Code
def sigma (κ : (a : α) → Kernel (β a) γ) : Kernel (Σ a, β a) γ where toFun x := κ x.1 x.2 measurable' := measurable_sigma_of_measurable_comp_mk fun a ↦ (κ a).measurable
New in v4.34.0-rc2-82-ga6c27a7 (2026-09-13), and its meaning has not changed since.
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, 10 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.