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lean4game/server/adam/Adam/Levels/LinearAlgebra/N04_Idempotent.lean

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import Adam.Metadata
import Mathlib.Algebra.Module.Submodule.Lattice
import Mathlib.Data.Real.Basic
import Mathlib.LinearAlgebra.Basic
Game "Adam"
World "Module2"
Level 4
Title "Lineare Abbildung"
Introduction
"
"
Statement
""
{R V : Type _} [Semiring R] [AddCommGroup V] [Module R V]
(p : V →ₗ[R] V)(h : p ∘ p = p) : LinearMap.ker p ⊓ LinearMap.range p = ⊥ := by
sorry
-- rw eq_bot_iff,
-- intros v hv,
-- rw submodule.mem_bot,
-- rw submodule.mem_inf at hv,
-- cases hv.2 with w hw,
-- rw ←hw,
-- rw ←h,
-- change p (p w) = _,
-- rw hw,
-- rw ←linear_map.mem_ker,
-- exact hv.1,