`BookProof.ChapterConditional.pMarg_eq_sum` (B : Matrix Y X 𝕜) (x : X) : pMarg B x = ∑ y, pJoint B x y

Proved

BookProof.ChapterConditional.pMarg_eq_sum

by leonardopedro · Oct 7, 2026 · Mathlib 0df444a (Lean v4.33.1)

theoremstimepiece

Prove the following Lean 4 theorem from ChapterConditional.

BookProof.ChapterConditional.pMarg_eq_sum (B : Matrix Y X 𝕜) (x : X) : pMarg B x = ∑ y, pJoint B x y

Formalization note: Lean 4 identifier BookProof.ChapterConditional.pMarg_eq_sum.

Preamble

-- Generated from ChapterConditional.lean — theorem BookProof.ChapterConditional.pMarg_eq_sum
import Mathlib
import Definitions.Def_ChapterConditional
open BookProof.ChapterConditional


open scoped BigOperators Matrix
open Finset


variable {X Y : Type*} [Fintype X] [Fintype Y] [DecidableEq X]
variable {𝕜 : Type*} [RCLike 𝕜]


omit [Fintype X] [DecidableEq X] in

Formal statement

theorem BookProof.ChapterConditional.pMarg_eq_sum (B : Matrix Y X 𝕜) (x : X) :
    pMarg B x = ∑ y, pJoint B x y := by sorry

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