You are an expert Lean4 and formal verification agent proving a Lean4 theorem. Your output **must** strictly adhere to the specified format.

### Input Information
You will receive the following components, relevant to the target theorem:
* <all_available_defs>: Definitions available from imported modules (either from the current Lean repository or from Mathlib)
* <all_available_lemmas>: Lemmas/theorems available that may assist the proof.
* <local_ctx>...</local_ctx>: The local file context (imports, namespaces, definitions, comments, etc.) from the top of the file up to—but not including—the target theorem or any previously defined local lemmas/theorems.
* <target_theorem>...</target_theorem>: The target theorem statement, ending with `:=`.

**Notes**
1. Definitions include their full bodies, but for definitions whose bodies contain proofs, the proof parts are replaced by `admit` (i.e., admit /- proof elided -/), while the rest of the definition is kept unchanged; lemmas include only their statements.
2. You may freely reference any definition or lemma contained in these tags without redefining them.
3. The tags for available definitions and lemmas (all_available_defs, all_available_lemmas) may be omitted if empty.

### Output Format & Requirements
Your output MUST contain a complete, syntactically correct Lean 4 proof for the target theorem.

**Strict Output Structure:**
<reasoning> 
...
</reasoning> 

<lean4_invented_lemmas>
-- each lemma is a full Lean 4 declaration with a complete proof
...
</lean4_invented_lemmas>

<lean4_proof>
-- Lean 4 proof body of the target theorem
...
</lean4_proof>

**Requirements:**
1. <reasoning> and <lean4_invented_lemmas> are OPTIONAL. Include them only if they aid proof construction.
2. <lean4_proof> MUST contain only the proof body (tactics/terms), starting by "by", NOT the theorem declaration.
3. <lean4_invented_lemmas> (if present) MUST contain syntactically correct lemma declarations that type checks AND complete proof bodies. Defining a lemma using `axiom` is NOT allowed.
4. <reasoning> contains high-level proof planning.
5. If you create a lemma under <lean4_invented_lemmas> whose name is namespaced (e.g., X.Y.Z), you MUST always refer to it using its fully qualified name. Do NOT rely on shortened names. For example, write rw [X.Y.Z], not rw [Z] for invented lemmas.
6. All Lean 4 code MUST be syntactically correct. No `sorry`, `admit`, or non-Lean text. Comments allowed using `--` or `/- ... -/`.
7. Follow the tags and structure EXACTLY. No extra text before, between, or after the sections.
8. Do NOT wrap invented lemmas in a `mutual` block unless they have genuine mutual recursion. Declare each lemma independently.

### Examples are provided here (example input are under "User Prompt", and example assistant response are under "Agent Response"):
Example 1 ------------------- 
User Prompt:
<all_available_defs>
structure BitVec (w : Nat) where
  /-- Construct a `BitVec w` from a number less than `2^w`.
  O(1), because we use `Fin` as the internal representation of a bitvector. -/
  ofFin ::

  /-- Interpret a bitvector as a number less than `2^w`.
  O(1), because we use `Fin` as the internal representation of a bitvector. -/
  toFin : Fin (hPow 2 w)
</all_available_defs>

<all_available_lemmas>
theorem List.getElem_append_left{α : Type u_1} {l₁ l₂ : List α} {i : Nat} (hn : i < l₁.length) : (l₁ ++ l₂)[i] = l₁[i]
theorem getElem_eq_testBit_toNat (x : BitVec w) (i : Nat) (h : i < w) :
  x[i] = x.toNat.testBit i := rfl
@[simp, grind =] theorem toNat_cons (b : Bool) (x : BitVec w) :
    (cons b x).toNat = (b.toNat <<< w) ||| x.toNat
@[simp, grind =] theorem getLsbD_of_ge (x : BitVec w) (i : Nat) (ge : w ≤ i) : getLsbD x i = false
theorem testBit_toNat (x : BitVec w) : x.toNat.testBit i = x.getLsbD i
</all_available_lemmas>

<local_ctx>
import Mathlib.Computability.NFA
import Mathlib.Data.FinEnum
import Mathlib.Data.Rel
import Mathlib.Data.Vector.Basic
import Blase.AutoStructs.ForLean

open Set
open Mathlib
open SetRel

-- this is better because card is defeq to n
instance (α : Type) : Inter (Language α) := ⟨Set.inter⟩
instance (α : Type) : Union (Language α) := ⟨Set.union⟩

/--
The set of `n`-tuples of bit vectors of an arbitrary width.
-/
structure BitVecs (n : Nat) where
  w : Nat
  bvs : List.Vector (BitVec w) n

def BitVecs.cast (bvs : BitVecs n) (h : n = n') : BitVecs n' :=
  { w := bvs.w, bvs := h ▸ bvs.bvs }

abbrev BitVecs.empty : BitVecs n := ⟨0, List.Vector.replicate n .nil⟩
abbrev BitVecs.singleton {w : Nat} (bv : BitVec w) : BitVecs 1 := ⟨w, bv ::ᵥ .nil⟩
abbrev BitVecs.pair {w : Nat} (bv1 bv2 : BitVec w) : BitVecs 2 := ⟨w, bv1 ::ᵥ bv2 ::ᵥ .nil⟩

/--
The set of `n`-tuples of bit vectors of an arbitrary width, encoded as a list of
bit vectors of width `n`. The width of the encoded bit vectors is the length of
the list.
-/
abbrev BitVecs' (n : Nat) := List (BitVec n)

@[simps]
def dec (bvs' : BitVecs' n) : BitVecs n where
  w := bvs'.length
  bvs := List.Vector.ofFn fun k => BitVec.ofFn fun i => bvs'[i].getLsbD k

@[simp]
</local_ctx>

<target_theorem>
lemma dec_snoc n (bvs' : BitVecs' n) (a : BitVec n) :
  dec (bvs' ++ [a]) =
    { w := bvs'.length + 1
      bvs := List.Vector.ofFn fun k =>
        BitVec.cons (a.getLsbD k) ((dec bvs').bvs.get k) } :=
</target_theorem>

Agent Response:
<reasoning> 
The goal is to understand what `dec` does after appending one more bitvector `a` to `bvs'`. By definition, `dec` builds a width `= length` and a vector of bitvectors whose `i`-th bit at position `k` is `bvs'[i].getLsbD k`. So for `bvs' ++ [a]`, we expect the width to increase by 1 and each resulting bitvector to be `BitVec.cons` of the new bit coming from `a`.

First, I use `ext` twice: once on the record to focus on the `bvs` field, and once on the resulting bitvector. This reduces everything to a pointwise statement:
for fixed `k` and `i` with `i < bvs'.length + 1`,
the bit `(bvs' ++ [a])[i].getLsbD k` should match the bit at index `i` of `BitVec.cons (a.getLsbD k) ((dec bvs').bvs.get k)`.

At this point I need a clean description of indexing into `BitVec.cons`: if we have `x : BitVec n`, then `(cons b x)[i]` should give `b` at the new “last” index `n` and `x[i]` otherwise. That motivates an auxiliary lemma `getElem_cons` expressing exactly this behavior, proved via the `testBit`/`toNat` characterization and a case split on `i < n`, `i = n`, `i > n`.

Using `getElem_cons`, the RHS becomes an `if` on whether `i = bvs'.length`. So I split into cases:
- If `i = bvs'.length`, then `(bvs' ++ [a])[i]` is the appended `a`, so both sides reduce to `a.getLsbD k`.
- If `i ≠ bvs'.length`, the bound `i < bvs'.length + 1` forces `i < bvs'.length`. Then `(bvs' ++ [a])[i] = bvs'[i]` by `List.getElem_append_left`, and the RHS takes the “else” branch and likewise gives the bit from `bvs'[i]`. In both subcases, `simp` (plus the definition of `dec`) finishes.

So the whole proof is: `ext` to bit level, unfold `dec` with `simp_all`, rewrite with `getElem_cons`, split on the boundary index `i = length bvs'`, and in the “< length” branch use `List.getElem_append_left` and bounds to line up both sides.
</reasoning> 

<lean4_invented_lemmas>
@[grind =]
theorem getElem_cons {b : Bool} {n} {x : BitVec n} {i : Nat} (h : i < n + 1) :
    (cons b x)[i] = if h : i = n then b else x[i] := by
  simp only [BitVec.getElem_eq_testBit_toNat, BitVec.toNat_cons, Nat.testBit_or]
  rw [Nat.testBit_shiftLeft]
  rcases Nat.lt_trichotomy i n with i_lt_n | i_eq_n | n_lt_i
  · have p1 : ¬(n ≤ i) := by omega
    have p2 : i ≠ n := by omega
    simp [p1, p2]
  · simp only [i_eq_n, ge_iff_le, Nat.le_refl, decide_true, Nat.sub_self, Nat.testBit_zero,
    Bool.true_and, BitVec.testBit_toNat, BitVec.getLsbD_of_ge, Bool.or_false]
    cases b <;> trivial
  · have p1 : i ≠ n := by omega
    have p2 : i - n ≠ 0 := by omega
    simp [p1, p2, Nat.testBit_bool_toNat]
</lean4_invented_lemmas>

<lean4_proof>
by
  ext k i hi <;> simp_all
  rw [getElem_cons]
  split
  next heq => simp_all
  next h =>
    have hlt : i < List.length bvs' := by simp at hi; omega
    rw [List.getElem_append_left hlt]
    simp
</lean4_proof>

### Your task:
<all_available_defs>
Fin in Init.Prelude
Vector in Init.Data.Vector.Basic
BitVec in Init.Prelude
BitVec.ofFin in Init.Prelude
Nat in Init.Prelude
Vector.ofFn in Init.Data.Vector.Basic
List in Init.Prelude
List.ofFn in Init.Data.List.OfFn
Nat.succ in Init.Prelude
NeZero in Init.Data.NeZero
Fin.isValue in Lean.Meta.Tactic.Simp.BuiltinSimprocs.Fin
reduceCtorEq in Lean.Meta.Tactic.Simp.BuiltinSimprocs.Core
Bool in Init.Prelude
List.foldr in Init.Data.List.Basic
List.foldl in Init.Prelude

@[elab_as_elim] def Fin.succRecOnSameFinType {motive : Fin r → Sort _}
    (zero : motive (0 : Fin r))
    (succ : ∀ i : Fin r, i + 1 < r → motive i → motive (i + 1)) : ∀ (i : Fin r), motive i
  | ⟨0, _⟩ => by admit /- proof elided -/
  | ⟨Nat.succ i_val, h⟩ => by admit /- proof elided -/

def getBit (k n : Nat) : Nat := (n >>> k) &&& 1

abbrev FunEquiv F α β := DFunEquiv F α fun _ => β

Fin.removeNth in Mathlib.Data.Fin.Tuple.Basic

def finUInt16Equiv : Fin (2 ^ 16) ≃ UInt16 where
  toFun := fun i => UInt16.ofFin i
  invFun := fun u => u.toFin
  left_inv _ := rfl
  right_inv _ := rfl

instance {α : Type u} : Slice (List α) Nat Nat (fun _ _ _ => True) (fun _ _ _ _ => List α) where
  slice xs start stop _ := xs.extract start stop

@[reducible]
def OracleStatement (i : Fin (k + 1)) : Fin (i.val + 1) → Type :=
  fun j =>
    evalDomain D x (∑ j' ∈ finRangeTo j.1, s j')
      → F

def outputRelation (cond : ∑ i, (s i).1 ≤ n) [DecidableEq F] (δ : ℝ≥0) :
    Set
      (
        (Statement F i.succ × (∀ j, OracleStatement D x s i.succ j)) ×
        Witness F s d i.succ.castSucc
      ) := sorry

abbrev AffSpanSet [NeZero k] (U : Fin k → ι → F) : Set (ι → F) :=
  (affineSpan F (Finset.univ.image U : Set (ι → F))).carrier

Function.Injective2 in Mathlib.Logic.Function.Basic

instance : ∀ j, SelectableType ((pSpecFoldRelay (L:=L)).Challenge j) :=
  instSelectableTypeChallengeAppend

abbrev PermuteDir := Unit ⊕ Unit

Matrix.of in Mathlib.LinearAlgebra.Matrix.Defs

def coreInteractionOracleRbrKnowledgeError (j : (pSpecCoreInteraction 𝔽q β (ϑ := ϑ)
    (h_ℓ_add_R_rate := h_ℓ_add_R_rate)).ChallengeIdx) : ℝ≥0 :=
    Sum.elim
      (f := fun i => sumcheckFoldKnowledgeError 𝔽q β (ϑ:=ϑ) (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i)
      (g := fun i => finalSumcheckKnowledgeError (L := L) i)
      (ChallengeIdx.sumEquiv.symm j)

hℓ_bound : ∀ i : Fin (M + 1), ∀ j : Fin ((P.foldingParam i) + 1),
    Fintype.card (Gen_α i j).parℓ = 2
  hℓ_bound' : ∀ i : Fin (M + 1), ∀ j : Fin ((P.foldingParam i) + 1),
    Fintype.card (parℓ_type i j) = 2

abbrev CNat (n : ℕ) : Type := (CayleyTower n).1

Gen_α : ∀ i : Fin (M + 1), ∀ j : Fin ((P.foldingParam i) + 1),
    ProximityGenerator (indexPowT (S i) (P.φ i) j) F :=
      fun i j => RSGenerator.genRSC (parℓ_type i j) (φ i j) (P.varCount i - j) (exp i j)

Fin.succ in Init.Data.Fin.Basic

def SkeletonNodeIndex.isRoot {s : Skeleton} (idx : SkeletonNodeIndex s) : Bool :=
  match idx with
  | SkeletonNodeIndex.ofLeaf => true
  | SkeletonNodeIndex.ofInternal => true
  | SkeletonNodeIndex.ofLeft _ => false
  | SkeletonNodeIndex.ofRight _ => false

RingHom.comp in Mathlib.Algebra.Ring.Hom.Defs

Unique in Mathlib.Logic.Unique

def toMvPolynomialDeg1 (p : MlPoly R n) : R⦃≤ 1⦄[X Fin n] :=
  ⟨toMvPolynomial p, by admit /- proof elided -/
  ⟩

def Verifier.KnowledgeStateFunction.id {rel : Set (Statement × Witness)} :
    (Verifier.id : Verifier oSpec Statement _ _).KnowledgeStateFunction init impl rel rel
      (Extractor.RoundByRound.id) where
  toFun | ⟨0, _⟩ => fun stmtIn _ witIn => (stmtIn, witIn) ∈ rel
  toFun_empty := fun _ => by admit /- proof elided -/

instance : ∀ j, OracleInterface ((pSpec F).Message j)
  | ⟨0, h⟩ => nomatch h
  | ⟨1, _⟩ => by admit /- proof elided -/

structure ProverInteractionWithOutput {ι : Type} (oSpec : OracleSpec ι) (Output : Type)
    {n : ℕ} (pSpec : ProtocolSpec n) extends
      ProverState n,
      ProverInit (PrvState 0),
      ProverRound oSpec pSpec,
      ProverOutput oSpec Output (PrvState (Fin.last n))

instance [VerifierFirst pSpec] : ∀ i, OracleInterface (pSpec.Message i) := isEmptyElim

@[simp]
abbrev SecondSumcheckChallenge : Type := Fin pp.ℓ_n → R

Ideal.span in Mathlib.RingTheory.Ideal.Span

structure KnowledgeStateFunction
    (relIn : Set (StmtIn × WitIn)) (relOut : Set (StmtOut × WitOut))
    (verifier : Verifier oSpec StmtIn StmtOut pSpec)
    {WitMid : Fin (n + 1) → Type}
    (extractor : Extractor.RoundByRound oSpec StmtIn WitIn WitOut pSpec WitMid)
    where
   
  toFun : (m : Fin (n + 1)) → StmtIn → Transcript m pSpec → WitMid m → Prop
   
  toFun_empty : ∀ stmtIn witMid,
    ⟨stmtIn, cast extractor.eqIn witMid⟩ ∈ relIn ↔ toFun 0 stmtIn default witMid
   
  toFun_next : ∀ m, pSpec.dir m = .P_to_V →
    ∀ stmtIn tr msg witMid, toFun m.succ stmtIn (tr.concat msg) witMid →
      toFun m.castSucc stmtIn tr (extractor.extractMid m stmtIn (tr.concat msg) witMid)
   
  toFun_full : ∀ stmtIn tr witOut,
    [fun stmtOut => (stmtOut, witOut) ∈ relOut
    | do (simulateQ impl (verifier.run stmtIn tr)).run' (← init)] > 0 →
    toFun (.last n) stmtIn tr (extractor.extractOut stmtIn tr witOut)

⟨val, by admit /- proof elided -/
  ⟩

GaloisField in Mathlib.FieldTheory.Finite.GaloisField

CommMonoidWithZero in Mathlib.Algebra.GroupWithZero.Defs

def Reduction.append (R₁ : Reduction oSpec Stmt₁ Wit₁ Stmt₂ Wit₂ pSpec₁)
    (R₂ : Reduction oSpec Stmt₂ Wit₂ Stmt₃ Wit₃ pSpec₂) :
      Reduction oSpec Stmt₁ Wit₁ Stmt₃ Wit₃ (pSpec₁ ++ₚ pSpec₂) where
  prover := Prover.append R₁.prover R₂.prover
  verifier := Verifier.append R₁.verifier R₂.verifier

@[inline, specialize, simp]
def oracleVerifier : OracleVerifier oSpec Statement OStatement Statement OStatement !p[] :=
  OracleVerifier.id

AlgEquiv in Mathlib.Algebra.Algebra.Equiv

PFunctor.Lens in ToMathlib.PFunctor.Basic

LinearMap.codRestrict in Mathlib.Algebra.Module.Submodule.LinearMap

def powMod (a b m : ℕ) : ℕ := Id.run do
  let mut x := a
  let mut n := b
  let mut res := 1

noncomputable def Basis.baseChangeRight (b : Basis ι K Left) : Basis ι Right (Left ⊗[K] Right) :=

@[ext]
structure VectorSpec (n : ℕ) where
  dir : Fin n → Direction
  length : Fin n → Nat

def InternalData.leftSubtree {α : Type} {s_left s_right : Skeleton}
    (tree : InternalData α (Skeleton.internal s_left s_right)) :
    InternalData α s_left :=
  match tree with
  | InternalData.internal _ left _right =>
    left

List.repr in Init.Data.Repr

e

embed := Function.Embedding.inl

@[reducible, simp] def OStmtIn := fun _ : Fin 2 => OStatement

def sumAll (n : ℕ) (D : Fin n → Finset R) : MvPolynomial (Fin n) R →ₗ[R] R :=

Polynomial.coeff in Mathlib.Algebra.Polynomial.Basic

def degree (P : Params ι F) : Fin (M + 1) → ℕ :=
  fun i => P.deg / ∏ j < i, (P.foldingParam j)

structure DomainSeparator (U : Type) [SpongeUnit U] (H : Type*) [DuplexSpongeInterface U H] where
   
  io : String
deriving Repr

multiplicity in Mathlib.RingTheory.Multiplicity

@[reducible, simp] def OStmtOut := fun _ : Fin 2 => OStatement

Mod in Init.Prelude

noncomputable def twiddleFactor (i : Fin ℓ) (u : Fin (2 ^ (ℓ + R_rate - i - 1))) : L :=
  ∑ (⟨k, hk⟩: Fin (ℓ + R_rate - i - 1)),
    if Nat.getBit k u.val = 1 then
      
        
      (normalizedW 𝔽q β ⟨i, by admit /- proof elided -/
      ⟩).eval (β ⟨i + 1 + k, by admit /- proof elided -/
      ⟩)
    else 0

def divide_by_2 (s : Finset ℕ) : Finset ℕ :=
  (erase_odd s).image (fun n => n / 2)

class Memory (ι : Type u) (α : ι → Type v) (M : Type w) where
   
  read (m : M) (i : ι) : α i
   
  write (m : M) (i : ι) (v : α i) : M

def finIdxOfIfTrue [BEq α] [LawfulBEq α] (a : α) (l : List α) (h : a ∈ l) : Fin l.length :=
  ⟨List.idxOf' a l, by admit /- proof elided -/
  ⟩

@[reducible]
def messageLength (vPSpec : VectorSpec n) (i : MessageIdx vPSpec) : Nat := vPSpec.length i

Array.size in Init.Prelude

noncomputable def ElocPolyF (ωs f : Fin n → F) (p : Polynomial F) : Polynomial F :=
  ElocPoly n (liftF ωs) (liftF f) p

def extract {n : ℕ} {α : Fin n → Sort*} (start stop : ℕ) (h1 : start ≤ stop) (h2 : stop ≤ n)
    (v : (i : Fin n) → α i) : (i : Fin (stop - start)) → α ⟨i + start, by admit /- proof elided -/
    ⟩ :=
  fun i ↦ v ⟨i + start, by admit /- proof elided -/
  ⟩

instance : ∀ j, OracleInterface ((pSpecRelay).Message j)
  | ⟨x, hj⟩ => by admit /- proof elided -/

instance [inst : SelectableType Chal] : ∀ i, SelectableType (Challenge ⟨!v[.V_to_P], !v[Chal]⟩ i)
  | ⟨0, _⟩ => inst

instance instTestLensComplete : testLens.IsComplete
      outerRelIn_Test innerRelIn_Test outerRelOut_Test innerRelOut_Test
      (fun ⟨⟨p, q, _⟩, _⟩ ⟨⟨f, _⟩, _⟩ => p * q = f) where
  proj_complete := fun ⟨p, q, t⟩ () hRelIn => by admit /- proof elided -/

AdjoinRoot.of in Mathlib.RingTheory.AdjoinRoot

@[reducible, simp]
def relOut : (StmtOut OStatement × ∀ i, OStmtOut OStatement i) → WitOut → Prop :=
  fun ⟨⟨q, r⟩, oStmt⟩ () => answer (oStmt 0) q = r

noncomputable def fold
  {S : Finset ι} (φ : ι ↪ F) (f : ι → F) (k : ℕ) (α : F) : indexPow S φ k → F :=
    fun x => (xPoly f φ k x).eval α

def hcons {n : ℕ} {α : Sort u} {β : Fin n → Sort u} (a : α) (b : (i : Fin n) → β i) :
    (i : Fin (n + 1)) → Fin.vcons α β i :=
  fcons (F := id) a b

noncomputable def listDecodingCollisionProbability
  (φ : ι ↪ F) (f : ι → F) (δ : ℝ) (s degree : ℕ)
  (h_nonempty : Nonempty (domainComplement φ)) : ENNReal :=
  Pr_{let r ←$ᵖ (Fin s → domainComplement φ)}[ ∃ (u u' : code φ degree),
                                    u.val ≠ u'.val ∧
                                    u.val ∈ relHammingBall (code φ degree) f δ ∧
                                    u'.val ∈ relHammingBall (code φ degree) f δ ∧
                                    ∀ i : Fin s,
                                    let uPoly := decodeLT u
                                    let uPoly' := decodeLT u'
                                    (uPoly : F[X]).eval (r i).1
                                      = (uPoly' : F[X]).eval (r i).1
                                    ]

@[inline, specialize]
def oracleVerifier : OracleVerifier oSpec
    Unit (fun _ : Fin 2 => OStatement)
    (Query OStatement) (fun _ : Fin 2 => OStatement) (pSpec OStatement) where

def coeffsToBitVec {n : ℕ} (coeffs : List (ZMod 2)) : BitVec n :=
  let val := List.foldr (fun c acc => acc * 2 + c.val) 0 (coeffs.take n)
  BitVec.ofNat n val

@[inline, specialize]
def eval (x : R) (p : UniPoly R) : R :=
  p.eval₂ (RingHom.id R) x

@[inline]
def seqCompose {m : ℕ} (Stmt : Fin (m + 1) → Type)
    {n : Fin m → ℕ} {pSpec : ∀ i, ProtocolSpec (n i)}
    (V : (i : Fin m) → Verifier oSpec (Stmt i.castSucc) (Stmt i.succ) (pSpec i)) :
    Verifier oSpec (Stmt 0) (Stmt (Fin.last m)) (seqCompose pSpec) := match m with
  | 0 => Verifier.id
  | _ + 1 => append (V 0) (seqCompose (Stmt ∘ Fin.succ) (fun i => V (Fin.succ i)))

@[reducible]
noncomputable def reductionFold :
  OracleReduction []ₒ
    (Statement F (0 : Fin (k + 1))) (OracleStatement D x s (0 : Fin (k + 1)))
      (Witness F s d (0 : Fin (k + 2)))
    (FinalStatement F k) (FinalOracleStatement D x s)
      (Witness F s d (Fin.last (k + 1)))
    (pSpecFold D x k s ++ₚ FinalFoldPhase.pSpec F)
 := OracleReduction.append
      (OracleReduction.seqCompose _ _ (fun (i : Fin (k + 1)) => Witness F s d i.castSucc)
        (FoldPhase.foldOracleReduction D x s d))
      (FinalFoldPhase.finalFoldOracleReduction D x (k := k) s d)

@[reducible]
def foldCommitOracleVerifier (i : Fin ℓ) (hCR : isCommitmentRound ℓ ϑ i) :
  OracleVerifier []ₒ
    (StmtIn := Statement (L := L) Context i.castSucc)
    (OStmtIn := OracleStatement 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) ϑ i.castSucc)
    (StmtOut := Statement (L := L) Context i.succ)
    (OStmtOut := OracleStatement 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) ϑ i.succ)
    (pSpec := pSpecFoldCommit 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i) :=
    OracleVerifier.append (oSpec:=[]ₒ)
      (pSpec₁ := pSpecFold (L:=L))
      (pSpec₂ := pSpecCommit 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i)
      (V₁ := foldOracleVerifier 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i)
      (V₂ := commitOracleVerifier 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i hCR)

FiniteDimensional in Mathlib.LinearAlgebra.FiniteDimensional.Defs

Pi.single in Mathlib.Algebra.Notation.Pi.Basic

instance instDCastPSigmaPSigma :
    DCast ((a : α) ×' (b : β a) ×' γ a b) (fun a => δ a.1 a.2.1 a.2.2) where
  dcast hc d := dcast₃ (by admit /- proof elided -/
  ) (by admit /- proof elided -/
  ) (by admit /- proof elided -/
  ) d
  dcast_id := by admit /- proof elided -/

Submodule.span in Mathlib.LinearAlgebra.Span.Defs

def pSpecCoreInteraction := (pSpecSumcheckFold 𝔽q β (ϑ:=ϑ) (h_ℓ_add_R_rate := h_ℓ_add_R_rate)) ++ₚ
  (pSpecFinalSumcheckStep (L:=L))

def dummyLastWitness :
    Witness (L := L) 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) (Fin.last ℓ) := {
  t := ⟨0, by admit /- proof elided -/
  ⟩,
  H := ⟨0, by admit /- proof elided -/
  ⟩,
  f := fun _ => 0
}

Algebra.TensorProduct.instCommSemiring in Mathlib.RingTheory.TensorProduct.Basic

abbrev Bwd : PermuteDir := Sum.inr ()

Ideal in Mathlib.RingTheory.Ideal.Defs

class DCast₂ (α : Sort*) (β : α → Sort*) (γ : (a : α) → β a → Sort*) [DCast α β] where
  dcast₂ : ∀ {a a' : α} {b : β a} {b' : β a'},
    (ha : a = a') → (dcast ha b = b') → γ a b → γ a' b'
  dcast₂_id : ∀ {a : α} {b : β a}, dcast₂ (Eq.refl a) dcast_eq = (id : γ a b → γ a b)

def InternalData.EquivIndexFun {α : Type} (s : Skeleton) :
    InternalData α s ≃ (SkeletonInternalIndex s → α) where
  toFun := fun tree idx => tree.get idx
  invFun := fun f => InternalData.ofFun s f
  left_inv := by admit /- proof elided -/

instance (k : ℕ) : Fintype (ConcreteBTField k) := (getBTFResult k).instFintype

def modByMonic [Field R] (p : UniPoly R) (q : UniPoly R) :
    UniPoly R :=
  (divModByMonicAux p q).2

Function.Embedding.inl in Mathlib.Logic.Embedding.Basic

noncomputable def commitOracleVerifier (i : Fin ℓ) (hCR : isCommitmentRound ℓ ϑ i) :
  OracleVerifier
    (oSpec := []ₒ)
    (StmtIn := Statement (L := L) Context i.succ)
    (OStmtIn := OracleStatement 𝔽q β (ϑ := ϑ)
      (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i.castSucc)
    (Oₘ := fun i => by admit /- proof elided -/
    )
    
    (StmtOut := Statement (L := L) Context i.succ)
    (OStmtOut := OracleStatement 𝔽q β (ϑ := ϑ)
      (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i.succ)
    (pSpec := pSpecCommit 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i) where

Finset.univ in Mathlib.Data.Fintype.Defs

@[inline, reducible]
protected def id :
    Witness.Lens OuterStmtIn OuterStmtOut OuterWitIn OuterWitOut OuterWitIn OuterWitOut :=
  ⟨Prod.snd, fun _ => Prod.snd⟩

sendMessage 
  | ⟨0, _⟩ => fun ⟨stmt, oStmt, wit⟩ => do
    let curH : ↥L⦃≤ 2⦄[X Fin (ℓ - ↑i.castSucc)] := wit.H
    let h_i : L⦃≤ 2⦄[X] := by admit /- proof elided -/

def inv : Prop :=
  
  trace = [] ∧ state = 0

DivisionRing in Mathlib.Algebra.Field.Defs

instance [ProverFirst pSpec] : ProverLast pSpec where
  prover_last' := by admit /- proof elided -/

def StraightlineExtractor (oSpec : OracleSpec ι) (Data Commitment : Type) :=
  Commitment → QueryLog oSpec → Data

@[inline, specialize]
def OracleVerifier.run [Oₘ : ∀ i, OracleInterface (pSpec.Message i)]
    (stmt : StmtIn) (oStmtIn : ∀ i, OStmtIn i) (transcript : FullTranscript pSpec)
    (verifier : OracleVerifier oSpec StmtIn OStmtIn StmtOut OStmtOut pSpec) :
      OracleComp oSpec (StmtOut × (∀ i, OStmtOut i)) := do
  let f := OracleInterface.simOracle2 oSpec oStmtIn transcript.messages
  let stmtOut ← simulateQ f (verifier.verify stmt transcript.challenges)
  let oStmtOut : ∀ i, OStmtOut i := fun i => match h : verifier.embed i with
  | .inl j => by admit /- proof elided -/
  | .inr j => by admit /- proof elided -/

def start {α : Type} (a : α) : OracleComp (α →ₒ Vector U SpongeSize.C) (DuplexSponge U C) := do
  let capacitySegment : Vector U SpongeSize.C ← query (spec := α →ₒ Vector U SpongeSize.C) () a
  let vecSponge := (Vector.replicate SpongeSize.R (0 : U)) ++ capacitySegment
  return {
    state := SpongeState.update (α := C) (0 : C) (vecSponge.cast (by admit /- proof elided -/
    )),
    absorbPos := 0,
    squeezePos := Fin.last SpongeSize.R
  }

PrvState := commitPrvState 𝔽q β (ϑ := ϑ) (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i

instance : LawfulToNat Nat where
  toNat_zero := rfl
  toNat_succ := fun _ => rfl

@[inline, specialize]
def Reduction.runWithLog (stmt : StmtIn) (wit : WitIn)
    (reduction : Reduction oSpec StmtIn WitIn StmtOut WitOut pSpec) :
      OracleComp (oSpec ++ₒ [pSpec.Challenge]ₒ)
        (((FullTranscript pSpec × StmtOut × WitOut) × StmtOut) ×
          QueryLog (oSpec ++ₒ [pSpec.Challenge]ₒ) × QueryLog oSpec) := do
  
  let ⟨proverResult, proveQueryLog⟩ ← reduction.prover.runWithLog stmt wit
  let ⟨stmtOut, verifyQueryLog⟩ ←
    liftM (simulateQ loggingOracle (reduction.verifier.run stmt proverResult.1)).run
  return ⟨⟨proverResult, stmtOut⟩, proveQueryLog, verifyQueryLog⟩

def removeNth (p : Fin (n + 1)) (s : Fin (n + 1) →₀ M) : Fin n →₀ M :=
  Finsupp.equivFunOnFinite.symm (Fin.removeNth p s : Fin n → M)

noncomputable def polyToPowerSeries𝕃 (H : F[X][Y])
  (P : F[X][Y])
    : PowerSeries (𝕃 H) :=
  PowerSeries.mk <| fun n =>
    liftToFunctionField (P.coeff n)

def rightpad {m : ℕ} {α : Sort*} (n : ℕ) (a : α) (v : Fin m → α) : Fin n → α :=
  fun i => if h : i < m then v ⟨i, h⟩ else a

instance {s} : LawfulFunctor (fun α => LeafData α s) :=

def γ (x₀ : F) (R : F[X][X][Y]) (H : F[X][Y]) [φ : Fact (Irreducible H)] : PowerSeries (𝕃 H) :=
  let subst (t : ℕ) : 𝕃 H :=
    match t with
    | 0 => fieldTo𝕃 (-x₀)
    | 1 => 1
    | _ => 0
  PowerSeries.subst (PowerSeries.mk subst) (PowerSeries.mk (α x₀ R H))

if state.nargString.size < 4 then
    .error { message := "Insufficient transcript remaining for hint" }
  else
    
    let byte0 := state.nargString[0]!.toNat
    let byte1 := state.nargString[1]!.toNat
    let byte2 := state.nargString[2]!.toNat
    let byte3 := state.nargString[3]!.toNat
    let length := byte0 + (byte1 <<< 8) + (byte2 <<< 16) + (byte3 <<< 24)
    let rest := state.nargString.extract 4 state.nargString.size

instance : DFunEquiv (∀ a : α, β a) α β where
  equiv := Equiv.refl _

GroupWithZero in Mathlib.Algebra.GroupWithZero.Defs

def oracleVerifier : OracleVerifier oSpec (StmtIn R) (OStmtIn R deg) (StmtOut R) (OStmtOut R deg)
    (pSpec R deg) where
  verify := fun target chal => do
    let evals : Vector R m ← (Vector.finRange m).mapM
      (fun i => query (spec := [OStmtIn R deg]ₒ) () (D i))
    guard (evals.sum = target)
    
    pure (sorry, chal default)
  embed := .inl
  hEq := fun i => by admit /- proof elided -/

Polynomial.comp in Mathlib.Algebra.Polynomial.Eval.Defs

@[inline] def succ (a : Cayley T) : Cayley T := add a one

Inv in Init.Prelude

@[ext]
structure OracleVerifier {ι : Type} (oSpec : OracleSpec ι)
    (StmtIn : Type) {ιₛᵢ : Type} (OStmtIn : ιₛᵢ → Type)
    (StmtOut : Type) {ιₛₒ : Type} (OStmtOut : ιₛₒ → Type)
    {n : ℕ} (pSpec : ProtocolSpec n)
    [Oₛᵢ : ∀ i, OracleInterface (OStmtIn i)]
    [Oₘ : ∀ i, OracleInterface (pSpec.Message i)]
    where

instance : ∀ i, SelectableType ((default : ProtocolSpec 0).Challenge i) := fun ⟨i, _⟩ => Fin.elim0 i

@[reducible, inline, specialize]
instance challengeOracleInterface {pSpec : ProtocolSpec n} :
    ∀ i, OracleInterface (pSpec.Challenge i) := fun i =>
  { Query := Unit
    Response := pSpec.Challenge i
    answer := fun c _ => c }

instance : VAdd (ι → F) (AffineSubspace F (ι → F)) := AffineSubspace.pointwiseVAdd

def PowerType (n : ℕ) : Type := dfoldr' n (fun _ => Type) (fun _ T => T → T) Nat

protected def cast (R : OracleReduction oSpec StmtIn OStmtIn WitIn StmtOut OStmtOut WitOut pSpec₁) :
    OracleReduction oSpec StmtIn OStmtIn WitIn StmtOut OStmtOut WitOut pSpec₂ where
  prover := R.prover.cast hn hSpec
  verifier := R.verifier.cast hn hSpec hOₘ

List.cons in Init.Prelude

instance : Inhabited (UniPolyC R) := ⟨#[], Trim.canonical_empty⟩

Subtype.val in Init.Prelude

def masterKStateProp (stmtIdx : Fin (ℓ + 1))
    (oracleIdx : Fin (ℓ + 1))
    (h_le : oracleIdx.val ≤ stmtIdx.val) (stmt : Statement (L := L) Context stmtIdx)
    (wit : Witness (L := L) 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) stmtIdx)
    (oStmt : ∀ j, (OracleStatement 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) ϑ (i := oracleIdx) j))
    (localChecks : Prop := True) : Prop :=
  let oracleWitnessConsistency: Prop := oracleWitnessConsistency (mp := mp) (𝓑 := 𝓑) 𝔽q β
    stmtIdx oracleIdx h_le stmt wit oStmt
  let badEventExists := badEventExistsProp (ϑ := ϑ) 𝔽q β oracleIdx
    (challenges := Fin.take (m := oracleIdx) (v := stmt.challenges) (h := by admit /- proof elided -/
    ))
    (oStmt := oStmt)
  localChecks ∧ (badEventExists ∨ oracleWitnessConsistency)

def buildMerkleTree_with_hash {s} (leaf_tree : LeafData α s) (hashFn : α → α → α) :
    (FullData α s) :=
  match leaf_tree with
  | LeafData.leaf a => FullData.leaf a
  | LeafData.internal left right =>
    let leftTree := buildMerkleTree_with_hash left hashFn
    let rightTree := buildMerkleTree_with_hash right hashFn
    let rootHash := hashFn (leftTree.getRootValue) (rightTree.getRootValue)
    FullData.internal rootHash leftTree rightTree

def subLeftFull (U : Matrix (Fin m) (Fin n) F) (c_reindex : Fin m → Fin n) :
  Matrix (Fin m) (Fin m) F := Matrix.submatrix U id c_reindex

abbrev MultilinearPoly (L : Type) [CommSemiring L] (ℓ : ℕ) := L⦃≤ 1⦄[X Fin ℓ]

@[reducible]
def Set.language {α β} (rel : Set (α × β)) : Set α :=
  Prod.fst '' rel

φ : ∀ i : Fin (M + 1), ∀ j : Fin ((P.foldingParam i) + 1), (indexPowT (S i) (P.φ i) j) ↪ F

Nat in Init.Prelude
</all_available_defs>

<all_available_lemmas>
List.length_ofFn in Init.Data.List.OfFn
List.getElem_ofFn in Init.Data.List.OfFn
List.get_eq_getElem in Init.Data.List.Lemmas
Fin.is_lt in Init.Data.Fin.Lemmas
Fin.eta in Init.Data.Fin.Lemmas
List.ext_getElem in Init.Data.List.Lemmas
List.getElem_dropLast in Init.Data.List.Lemmas
List.length_dropLast in Init.Data.List.Lemmas
add_tsub_cancel_right in Mathlib.Algebra.Order.Sub.Defs
Fin.coe_ofNat_eq_mod in Mathlib.Data.Fin.Basic
Fin.val_succ in Init.Data.Fin.Lemmas
List.ofFn_succ in Init.Data.List.OfFn
Nat.zero_mod in Init.Data.Nat.Div.Basic
add_zero in Mathlib.Algebra.Group.Defs
ne_eq in Init.SimpLemmas
not_false_eq_true in Init.SimpLemmas
BitVec.getElem_ofFin in Init.Data.BitVec.Lemmas
BitVec.getLsb_eq_getElem in Init.Data.BitVec.Basic
Bool.false_eq_true in Init.Data.Bool
Fin.getElem_fin in Init.GetElem
Nat.sub_lt_of_lt in Init.Data.Nat.Basic
Vector.getElem_ofFn in Init.Data.Vector.OfFn
add_sub_assoc in Mathlib.Algebra.Group.Defs
sub_self in Mathlib.Algebra.Group.Defs
Fin.cast_succ_eq in Init.Data.Fin.Lemmas
Fin.cast_zero in Init.Data.Fin.Lemmas
Fin.coe_cast in Init.Data.Fin.Lemmas
Fin.eq_mk_iff_val_eq in Init.Data.Fin.Lemmas
Fin.mk_zero' in Mathlib.Data.Fin.Basic
Fin.val_eq_zero in Init.Data.Fin.Lemmas
List.foldl_cons in Init.Data.List.Basic
List.foldl_nil in Init.Data.List.Basic
List.foldr_cons in Init.Data.List.Basic
List.foldr_nil in Init.Data.List.Basic
List.ofFn_zero in Init.Data.List.OfFn
Nat.lt_of_lt_of_eq in Init.Data.Nat.Basic
Nat.mod_succ in Init.Data.Nat.Lemmas
tsub_self in Mathlib.Algebra.Order.Sub.Basic
zero_add in Mathlib.Algebra.Group.Defs

lemma testBit_true_eq_getBit_eq_1 (k n : Nat) : n.testBit k = ((Nat.getBit k n) = 1)

lemma testBit_false_eq_getBit_eq_0 (k n : Nat) :
  (n.testBit k = false) = ((Nat.getBit k n) = 0)

lemma getBit_of_sub_two_pow_of_bit_1 {n i j: ℕ} (h_getBit_eq_1: getBit i n = 1) :
  getBit j (n - 2^i) = (if j = i then 0 else getBit j n)

lemma and_two_pow_eq_two_pow_of_getBit_1 {n i : ℕ} (h_getBit: getBit i n = 1) :
    n &&& (2 ^ i) = 2 ^ i

lemma getBit_of_xor {n m k: ℕ} : getBit k (n ^^^ m) = getBit k n ^^^ getBit k m

lemma getBit_two_pow {i k : ℕ} : (getBit k (2^i) = if i == k then 1 else 0)

lemma xor_eq_sub_iff_submask {n m : ℕ} (h: m ≤ n) : n ^^^ m = n - m ↔ n &&& m = m

lemma sum_eq_xor_plus_twice_and (n : Nat) : ∀ m : ℕ, n + m = (n ^^^ m) + 2 * (n &&& m)

lemma and_by_split_lowBits {n m n1 m1 bn bm : ℕ} (h_bn : bn < 2) (h_bm : bm < 2)
  (h_n : n = n1 * 2 + bn) (h_m : m = m1 * 2 + bm):
  n &&& m = (n1 &&& m1) * 2 + (bn &&& bm)

lemma div_2_form {nD2 b : ℕ} (h_b : b < 2):
  (nD2 * 2 + b) / 2 = nD2

lemma or_by_split_lowBits {n m n1 m1 bn bm : ℕ} (h_bn : bn < 2) (h_bm : bm < 2)
  (h_n : n = n1 * 2 + bn) (h_m : m = m1 * 2 + bm):
  n ||

lemma xor_by_split_lowBits {n m n1 m1 bn bm : ℕ} (h_bn : bn < 2) (h_bm : bm < 2)
  (h_n : n = n1 * 2 + bn) (h_m : m = m1 * 2 + bm):
  n ^^^ m = (n1 ^^^ m1) * 2 + (bn ^^^ bm)

lemma Fin.val_add_one' (a : Fin r) (h_a_add_1 : a + 1 < r) : (a + 1).val = a.val + 1

theorem foldr_split_inner {α : Type u} {β : Type v} (f : α → β → β) (init : β)
    (l : List α) (h : l ≠ []): foldr (f:=f) (init:=init) (l)
    = foldr (f:=f) (init:=f (l.getLast (by omega)) (init)) (l.dropLast)

theorem append_getLast_dropLast {α : Type u} (l : List α) (h : l ≠ []) :
  l.dropLast ++ [l.getLast h] = l

theorem foldl_split_outer {α : Type u} {β : Type v} (f : α → β → α) (init : α)
    (l : List β) (h : l ≠ []): foldl (f:=f) (init:=init) (l)
    = f (foldl (f:=f) (init:=init) (l.dropLast)) (l.getLast (by omega))

@[simp]
lemma toFun_invFun (f : ∀ a, β a) : inst.equiv.toFun (equiv.invFun f : F) = f

omit [DecidableEq L] [DecidableEq 𝔽q] h_Fq_char_prime hF₂ hβ_lin_indep h_β₀_eq_1 in
theorem intermediateNormVpoly_comp (i : Fin ℓ) (k : Fin (ℓ - i + 1))
  (l : Fin (ℓ - (i.val + k.val) + 1)) :
  intermediateNormVpoly 𝔽q β h_ℓ_add_R_rate (i := ⟨i, by omega⟩) (k:=⟨k + l, by
      simp only; omega⟩) =
    (intermediateNormVpoly 𝔽q β h_ℓ_add_R_rate (i := ⟨i+k, by omega⟩) (k:=⟨l, by
      simp only; omega⟩)).comp (
  intermediateNormVpoly 𝔽q β h_ℓ_add_R_rate (i := ⟨i, by omega⟩) (k:=⟨k, by
      simp only; omega⟩)
  )

@[simp] theorem idxOf'_nil [BEq α] {a : α} : idxOf' a [] = 0

lemma lt_two_pow_of_lt_two_pow_exp_le (x i j: ℕ)
    (h_x_lt_2_pow_i: x < 2^i) (h_i_le_j: i ≤ j): x < 2^j

theorem sum_of_root_and_inverse_is_t1
    {curBTField : Type*} [Field curBTField]
    (u : curBTField) (t1 : curBTField) -- here t1 is already lifted to curBTField
    (specialElementNeZero : u ≠ 0)
    (eval_prevPoly_at_root : u ^ 2 + t1 * u + 1 = 0)
    (sumZeroIffEq : ∀ (x y : curBTField), x + y = 0 ↔ x = y) :
    u + u⁻¹ = t1

@[simp]
lemma challengeOracleInterface_append_range_inl (j : pSpec₁.ChallengeIdx) :
    [(pSpec₁ ++ₚ pSpec₂).Challenge]ₒ.range (.inl j) = pSpec₁.Challenge j

theorem congrArg₄ {α β γ δ ε : Sort*} {f : α → β → γ → δ → ε} {a a' : α} {b b' : β} {c c' : γ}
    {d d' : δ} (h : a = a') (h' : b = b') (h'' : c = c') (h''' : d = d') :
      f a b c d = f a' b' c' d'

omit [Fintype σ] in
theorem singleEqPolynomial_degreeOf (r : R) (i j : σ) :
    degreeOf i (singleEqPolynomial r (X j)) ≤ if i = j then 1 else 0

theorem prod_X_sub_C_eq_X_pow_card_sub_X :
  (∏ c ∈ (Finset.univ : Finset Fq), (Polynomial.X - Polynomial.C c)) =
    Polynomial.X^(Fintype.card Fq) - Polynomial.X

lemma Xⱼ_zero_eq_one (ℓ : ℕ) (h_ℓ : ℓ ≤ r) :
  Xⱼ 𝔽q β ℓ h_ℓ ⟨0, by exact Nat.two_pow_pos ℓ⟩ = 1

lemma mem_image_support_coeff_finSuccEquivNth {f : MvPolynomial (Fin (n + 1)) R} {i : ℕ} {x} :
    x ∈ Finsupp.insertNth p i '' ((finSuccEquivNth R p f).coeff i).support ↔
      x ∈ f.support ∧ x p = i

lemma degree_normalizedW (i : Fin r) :
  (normalizedW 𝔽q β i).degree = (Fintype.card 𝔽q)^(i.val)

private lemma choose_2_eq_half_f :
  choose_2 = (1/2) * f

theorem ZMod.powNeOfPowMod :
    ∀ {n a' q c : ℕ} (a : ZMod n), (a' : ZMod n) = a → decide (n ≥ 2) = true →
      Nat.mod (Nat.pow a' ((n - 1) / q)) n = c → decide (c ≠ 1) = true → a ^ ((n - 1) / q) ≠ 1

theorem cast_symm {α β : Sort u} {h : α = β} {a : α} {b : β} :
    cast h a = b ↔ a = cast h.symm b

@[simp] theorem rightpad_suffix (n : Nat) (unit : α) (l : List α) :
    replicate (n - l.length) unit <:+ rightpad n unit l

lemma h_middle_sub {k : ℕ} : 2 ^ (k - 1) - 1 - 0 + 1 = 2 ^ (k - 1)

@[simp]
theorem hflatten_zero {n : Fin 0 → ℕ} {α : (i : Fin 0) → (j : Fin (n i)) → Sort*}
    {v : (i : Fin 0) → (j : Fin (n i)) → α i j} : hflatten v = !h[]

@[simp]
theorem Basis_cast_index_apply {α β i j : ℕ} {k : Fin j}
    (h_le : α ≤ β) (h_eq : i = j)
    {b : @Basis (Fin (i)) (ConcreteBTField α) (ConcreteBTField β) _ _
      (@ConcreteBTFieldAlgebra (l := α) (r := β) (h_le := h_le)).toModule} :
  let castBasis : @Basis (Fin j) (ConcreteBTField α) (ConcreteBTField β) _ _
    (@ConcreteBTFieldAlgebra (l:=α) (r:=β) (h_le:=h_le)).toModule :=
    cast (by exact Basis_cast_index_eq i j α β h_le h_eq) b
  (castBasis k) = b (Fin.cast (h_eq.symm) k)

@[simp]
theorem cast_id :
    OracleProver.cast rfl rfl =
      (id : OracleProver oSpec StmtIn OStmtIn WitIn StmtOut OStmtOut WitOut pSpec₁ → _)

theorem whir_rbr_soundness
    [SelectableType F] {d dstar : ℕ}
  -- P : set of M + 1 parameters including foldingParamᵢ, varCountᵢ, φᵢ, repeatParamᵢ,
  --

theorem lagrangeToMonoLevel_monoToLagrangeLevel_id (v : Vector R (2 ^ n)) (i : Fin n) :
  lagrangeToMonoLevel i (monoToLagrangeLevel i v) = v

theorem srKnowledgeSoundness_implies_knowledgeSoundness
    (relIn : Set (StmtIn × WitIn)) (relOut : Set (StmtOut × WitOut))
    (verifier : Verifier oSpec StmtIn StmtOut pSpec)
    (srInit : ProbComp (srChallengeOracle StmtIn pSpec).FunctionType)
    (srImpl : QueryImpl oSpec (StateT (srChallengeOracle StmtIn pSpec).FunctionType ProbComp))
    (srKnowledgeError : ℝ≥0) :
      Verifier.StateRestoration.knowledgeSoundness srInit srImpl relIn relOut
        verifier srKnowledgeError →
      knowledgeSoundness init impl relIn relOut verifier srKnowledgeError

@[simp]
theorem fflatten₂_two_eq_append {A : Sort u} {B : Sort v} {F : A → B → Sort w} {n : Fin 2 → ℕ}
    {α : (i : Fin 2) → (j : Fin (n i)) → A}
    {β : (i : Fin 2) → (j : Fin (n i)) → B}
    {v : (i : Fin 2) → (j : Fin (n i)) → F (α i j) (β i j)} :
    fflatten₂ v = fappend₂ (F := F) (v 0) (v 1)

private lemma johnson_denom [Zero F]
  (h_card : 2 ≤ (Fintype.card F))
  :
  (Fintype.card F / (Fintype.card F - 1)) *
  ((1 - e B 0 / n) ^ 2  + (e B 0) ^ 2 / ((Fintype.card F - 1) * n^2) - 1 + d B/n)
  =
  (1 - ((Fintype.card F) / (Fintype.card F - 1)) *
  (e B 0 / n)) ^ 2 - (1 - ((Fintype.card F) / (Fintype.card F - 1)) * (d B/n))

lemma sub_middle_of_pow2_with_one_canceled {k : ℕ} (h_k : 1 ≤ k) : 2 ^ k - 1 - 2 ^ (k - 1) + 1
  = 2 ^ (k - 1)

@[simp]
lemma finite_possibleDeltas : (possibleDeltas U V).Finite

theorem not_exists_of_decoder_eq_none {e k : ℕ} [NeZero n] {ωs f : Fin n → F}
  (he : 2 * e < n - k + 1)
  (hn : k ≤ n)
  (h_inj : Function.Injective ωs)
  (h_none : decoder e k ωs f = none)
  : ¬∃p : F[X], Δ₀(f, p.eval ∘ ωs) ≤ e ∧ p.natDegree < k

@[simp]
theorem LeafData.get_ofFun {α} {s} (f : SkeletonLeafIndex s → α) :
    (LeafData.ofFun s f).get = f

theorem heq_of_dcast (ha : a = a') (hb : dcast ha b = b') : HEq b b'

theorem append_left_injective (b : Fin n → α) : Function.Injective (@Fin.append m n α · b)

@[simp]
theorem dflatten_zero {n : Fin 0 → ℕ} {motive : (k : Fin (vsum n)) → Sort*}
    {v : (i : Fin 0) → (j : Fin (n i)) → motive (embedSum i j)} :
    dflatten (motive := motive) v = fun k => Fin.elim0 k

lemma fold_f_g_poly
  {S : Finset ι} {φ : ι ↪ F} {k m : ℕ}
  {φ_0 : (indexPowT S φ 0) ↪ F} {φ_k : (indexPowT S φ k) ↪ F}
  [Fintype (indexPowT S φ 0)] [DecidableEq (indexPowT S φ 0)] [Smooth φ_0]
  [Fintype (indexPowT S φ k)] [DecidableEq (indexPowT S φ k)] [Smooth φ_k]
  [∀ i : ℕ, Neg (indexPowT S φ i)]
  (αs : Fin k → F) (hk : k ≤ m)
  (f : smoothCode φ_0 m) (g : smoothCode φ_k (m-k)) :
  let fPoly

lemma irreducible_factorization_of_gs_solution
  {k : ℕ}
  (h_gs : ModifiedGuruswami m n k ωs Q u₀ u₁) :
  ∃ (C : F[Z][X]) (R : List F[Z][X][Y]) (f : List ℕ) (e : List ℕ),
    R.length = f.length ∧
    f.length = e.length ∧
    ∀ eᵢ ∈ e, 1 ≤ eᵢ ∧
    ∀ Rᵢ ∈ R, Rᵢ.Separable ∧
    ∀ Rᵢ ∈ R, Irreducible Rᵢ ∧
    Q = (Polynomial.C C) *
        ∏ (Rᵢ ∈ R.toFinset) (fᵢ ∈ f.toFinset) (eᵢ ∈ e.toFinset),
          (Rᵢ.comp ((Y : F[Z][X][Y]) ^ fᵢ))^eᵢ

lemma gamma_eq_P
  (h_gs : ModifiedGuruswami m n k ωs Q u₀ u₁)
  :
  γ' x₀ (R k δ x₀ h_gs) (irreducible_H k (x₀ := x₀) (δ := δ) h_gs) =
  AppendixA.polyToPowerSeries𝕃 _ 
    (P k δ x₀ h_gs)

@[simp]
theorem happend_empty {α : Fin m → Sort u} {β : Fin 0 → Sort u} (v : (i : Fin m) → α i) :
    happend v !h⟨β⟩[] = v

@[simp]
theorem card_filter_prod_self_eq :
  #({x ∈ s ×ˢ s | x.1 = x.2}) = #s

theorem coreInteractionOracleReduction_perfectCompleteness (hInit : init.neverFails) :
    OracleReduction.perfectCompleteness
      (pSpec := pSpecCoreInteraction 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate))
      (relIn := roundRelation (mp := BBF_SumcheckMultiplierParam) 𝔽q β (ϑ:=ϑ)
        (h_ℓ_add_R_rate := h_ℓ_add_R_rate) (𝓑:=𝓑) 0)
      (relOut := finalSumcheckRelOut 𝔽q β (ϑ:=ϑ) (h_ℓ_add_R_rate := h_ℓ_add_R_rate))
      (oracleReduction := coreInteractionOracleReduction 𝔽q β (ϑ:=ϑ) (𝓑:=𝓑))
      (init := init)
      (impl := impl)

@[simp]
theorem Iio_zero : Iio (0 : Fin (n + 1)) = ∅

@[simp]
lemma relHammingDistToCode_mem_relHammingDistRange [Nonempty ι] [DecidableEq F] :
  δᵣ(c, C) ∈ relHammingDistRange ι

@[simp]
theorem removeNth_apply : removeNth p s i = s (p.succAbove i)

theorem add_zero {n : ℕ} (a : CNat (n + 1)) : a + 0 = a

@[to_additive (attr := simp)]
theorem prod_Iic_zero : ∏ j ∈ Iic 0, v j = v 0

theorem succ'_ne_zero (n : Nat) : succ' n ≠ 0

theorem liftContext_rbr_knowledgeSoundness [Inhabited InnerStmtOut] [Inhabited InnerWitIn]
    {outerRelIn : Set (OuterStmtIn × OuterWitIn)} {outerRelOut : Set (OuterStmtOut × OuterWitOut)}
    {innerRelIn : Set (InnerStmtIn × InnerWitIn)} {innerRelOut : Set (InnerStmtOut × InnerWitOut)}
    {rbrKnowledgeError : pSpec.ChallengeIdx → ℝ≥0}
    {stmtLens : Statement.Lens OuterStmtIn OuterStmtOut InnerStmtIn InnerStmtOut}
    {witLens : Witness.InvLens OuterStmtIn OuterWitIn OuterWitOut InnerWitIn InnerWitOut}
    (V : Verifier oSpec InnerStmtIn InnerStmtOut pSpec)
    [lensKS : Extractor.Lens.IsKnowledgeSound outerRelIn innerRelIn outerRelOut innerRelOut
      (V.compatStatement stmtLens) (fun _ _ => True) ⟨stmtLens, witLens⟩]
    (h : V.rbrKnowledgeSoundness init impl innerRelIn innerRelOut rbrKnowledgeError) :
      (V.liftContext stmtLens).rbrKnowledgeSoundness init impl outerRelIn outerRelOut
        rbrKnowledgeError

lemma split_join_eq_split {k : ℕ} (h_pos : k > 0)
    (hi_btf lo_btf : ConcreteBTField (k - 1)) :
    split h_pos (《 hi_btf, lo_btf 》) = (hi_btf, lo_btf)

theorem degree_finSuccEquivNth {f : MvPolynomial (Fin (n + 1)) R} (h : f ≠ 0) :
    (finSuccEquivNth R p f).degree = degreeOf p f

@[simp]
lemma liftF'_liftF : Function.LeftInverse liftF' (liftF (α := α) (n := n))

omit [CharP L 2] [DecidableEq 𝔽q] hF₂ h_β₀_eq_1 [NeZero 𝓡] in
lemma take_snoc_oracle_eq_oStmtIn (i : Fin ℓ)
    (oStmtIn : (j : Fin (toOutCodewordsCount ℓ ϑ i.castSucc)) →
      OracleStatement 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) ϑ i.castSucc j)
    (newOracleFn : OracleFunction 𝔽q β (h_ℓ_add_R_rate := h_ℓ_add_R_rate) i.succ) :
    (take_snoc_oracle 𝔽q β i oStmtIn newOracleFn) = oStmtIn

theorem add_coeff {p q : UniPoly Q} {i : ℕ} (hi : i < (add_raw p q).size) :
  (add_raw p q)[i] = p.coeff i + q.coeff i

lemma concrete_mul_one
  (prevBTFieldProps : ConcreteBTFieldProps (k := k - 1))
  (a : ConcreteBTField k) : concrete_mul a (one (k:=k)) = a

Fin.eta in Init.Data.Fin.Lemmas

@[simp]
theorem addCases'_right {m n : ℕ} {α : Fin m → Sort u} {β : Fin n → Sort u}
    (left : (i : Fin m) → α i) (right : (j : Fin n) → β j) (i : Fin n) :
      addCases' left right (Fin.natAdd m i) = (Fin.append_right α β i) ▸ (right i)

theorem ConcreteBTFieldAlgebra_apply_assoc (l mid r : ℕ)
    (h_l_le_mid : l ≤ mid) (h_mid_le_r : mid ≤ r) :
    ∀ x : ConcreteBTField l,
    (@ConcreteBTFieldAlgebra (l:=l) (r:=r) (h_le:=by
      exact Nat.le_trans h_l_le_mid h_mid_le_r)).algebraMap x =
    (@ConcreteBTFieldAlgebra (l:=mid) (r:=r) (h_le:=h_mid_le_r)).algebraMap
      ((@ConcreteBTFieldAlgebra (l:=l) (r:=mid) (h_le:=h_l_le_mid)).algebraMap x)

theorem fcons₂_injective2 {α₁ : A} {α₂ : B} {β₁ : Fin n → A} {β₂ : Fin n → B} :
    Function.Injective2 (@fcons₂ A B F₂ n α₁ β₁ α₂ β₂)

theorem lagrangeBasis_getElem {w : Vector R n} (i : Fin (2 ^ n)) :
    (lagrangeBasis w)[i] = ∏ j : Fin n, if (BitVec.ofFin i).getLsb j then w[j] else 1 - w[j]

@[simp]
lemma degreeX_monomialXY {n m : ℕ} {a : F} (ha : a ≠ 0) :
    degreeX (monomialXY n m a) = n

@[simp]
theorem toNat_zero : toNat zero = 0

have h_pb'_dim : bCast.dim = 2 := by
      dsimp [bCast]
      rw [PowerBasis.dim_of_eq_rec (r1:=r1) (r:=r) (h_r:=h_r) (b:=b)]
      exact h_pb_dim

@[simp]
lemma eval₂AlgHom_apply {A : Type w} {B : Type*} [CommSemiring A] [CommSemiring B]
    [PolynomialLike A P] [Algebra R A] [IsScalarTower R A P] [Algebra R B]
    (f : A →ₐ[R] B) (b : B) (p : P) :
    (eval₂AlgHom f b) p = eval₂ f b p

theorem cast_injective : Function.Injective (ChallengeIdx.cast hn hSpec)

lemma toPoly_trim [LawfulBEq R] {p : UniPoly R} : p.trim.toPoly = p.toPoly

theorem degrees_C_mul_le (p : MvPolynomial σ R) (c : R) : (C c * p).degrees ≤ p.degrees

theorem simulateQ'_eq_simulateQ [AlternativeMonad m] [LawfulMonad m]
    {so : QueryImpl spec m} (oa : OracleComp spec α) (h : oa.neverFails) :
      simulateQ' so oa h = simulateQ so oa

omit [NoZeroDivisors 𝔽] in
lemma foldNth_zero {s : ℕ} {α : 𝔽} : foldNth (2 ^ s) 0 α = 0

theorem induct [LawfulBEq R] {motive : UniPoly R → Prop}
  (case1 : ∀ p, p.trim = #[] → (∀ i, (hi : i < p.size) → p[i] = 0) → motive p)
  (case2 : ∀ p : UniPoly R, ∀ k : Fin p.size, p.trim = p.extract 0 (k + 1)
    → p[k] ≠ 0 → (∀ j : ℕ, (hj : j < p.size) → j > k → p[j] = 0) → motive p)
  (p : UniPoly R) : motive p

theorem matchSize_comm (l₁ : List α) (l₂ : List α) (unit : α) :
    matchSize l₁ l₂ unit = (matchSize l₂ l₁ unit).swap

lemma sDomain_card (i : Fin r) (h_i : i < ℓ + R_rate) :
    Fintype.card (sDomain 𝔽q β h_ℓ_add_R_rate i) = (Fintype.card 𝔽q)^(ℓ + R_rate - i)

theorem toFun_eq_const_plus (t : AssocNat) : ∀ m : Nat, t m = t 0 + m

theorem snoc_support :
    (s.snoc y).support ⊆ insert (Fin.last n) (s.support.map Fin.castSuccEmb)

theorem prime_37 : Nat.Prime 37

@[simp]
theorem oracleReduction_completeness (h : init.neverFails)
    (hRel : ∀ stmtIn oStmtIn witIn,
      ((stmtIn, oStmtIn), witIn) ∈ relIn →
      ((mapStmt stmtIn, mapOStmt embedIdx hEq oStmtIn), mapWit stmtIn witIn) ∈ relOut) :
    (oracleReduction oSpec mapStmt mapWit embedIdx hEq).perfectCompleteness init impl
      relIn relOut

lemma extract_start_zero_eq_take {n : ℕ} {α : Fin n → Sort*} (stop : ℕ) (h : stop ≤ n)
    (v : (i : Fin n) → α i) : extract 0 stop (Nat.zero_le _) h v = take stop h v

lemma geometric_sum_units {F : Type*} [Field F] [DecidableEq F] {r : Fˣ} {a : ℕ} :
  ∑ j ∈ range (a + 1), (r ^ j : F) =
    if r = 1 then (a + 1 : F)
    else (1 - r ^ (a + 1)) / (1 - r)

@[simp]
lemma elocPolyF_deg {ωs f : Fin n → F} : (ElocPolyF ωs f p).natDegree = Δ₀(f, p.eval ∘ ωs)

Nat.zero_add in Init.Data.Nat.Basic

lemma algebraMap_succ_eq_zero_x {k : ℕ} (h_pos : k > 0) (x : ConcreteBTField (k - 1)) :
  letI instAlgebra := ConcreteBTFieldAlgebra (l:=k-1) (r:=k) (h_le:=by omega)
  algebraMap (ConcreteBTField (k - 1)) (ConcreteBTField k) x = 《 0, x 》

@[simp]
theorem vflatten_embedSum {m : ℕ} {n : Fin m → ℕ} (v : (i : Fin m) → Fin (n i) → α) (i : Fin m)
    (j : Fin (n i)) : vflatten v (embedSum i j) = v i j

lemma normalizedW_eq_qMap_composition (ℓ R_rate : ℕ) (i : Fin r) :
    normalizedW 𝔽q β i = qCompositionChain 𝔽q β (ℓ:=ℓ) (R_rate:=R_rate) i

lemma concreteTowerAlgebraMap_succ (l r : ℕ) (h_le : l ≤ r) :
  concreteTowerAlgebraMap (l:=l) (r:=r + 1) (h_le:=by omega) =
  (concreteTowerAlgebraMap (l:=r) (r:=r + 1) (h_le:=by omega)).comp
  (concreteTowerAlgebraMap (l:=l) (r:=r) (h_le:=by omega))

@[simp]
lemma halfNumFullRounds_mul_2_eq_numFullRounds :
    params.halfNumFullRounds * 2 = params.numFullRounds

omit [DecidableEq L] [Fintype 𝔽q] hβ_lin_indep in
lemma W_ne_zero (i : Fin r) : (W 𝔽q β i) ≠ 0

theorem join_of_split {k : ℕ} (h_pos : k > 0) (x : ConcreteBTField k)
    (hi_btf lo_btf : ConcreteBTField (k - 1))
    (h_split_eq : split h_pos x = (hi_btf, lo_btf)) :
    x = 《 hi_btf, lo_btf 》

theorem divSum?_is_some_iff_lt_sum {m : ℕ} {n : Fin m → ℕ} {k : ℕ} :
    (divSum? n k).isSome ↔ k < ∑ i, n i

theorem two_pow_ne_zero (n : ℕ) : 2 ^ n ≠ 0

@[simp]
theorem OracleReduction.id_run (stmt : StmtIn) (oStmt : ∀ i, OStmtIn i) (wit : WitIn) :
    (OracleReduction.id : OracleReduction oSpec StmtIn OStmtIn WitIn _ _ _ _).run stmt oStmt wit =
      pure ⟨⟨default, ⟨stmt, oStmt⟩, wit⟩, ⟨stmt, oStmt⟩⟩

theorem add_coeff? (p q : UniPoly Q) (i : ℕ) :
  (add_raw p q).coeff i = p.coeff i + q.coeff i

omit [DecidableEq 𝔽q] hF₂ in
lemma getSDomainBasisCoeff_of_iteratedQuotientMap
    [NeZero R_rate] (i : Fin ℓ) (k : ℕ)
    (h_bound : i.val + k ≤ ℓ) (x : (sDomain 𝔽q β
    h_ℓ_add_R_rate) ⟨i, by omega⟩) :
    let y := iteratedQuotientMap (i := i) (k:=k) (h_bound:=h_bound) (x:=x)
    ∀ (j: Fin (ℓ + R_rate - (i + k))),
    ((sDomain_basis 𝔽q β h_ℓ_add_R_rate (i := ⟨↑i + k, by omega⟩) (h_i := by
      simp only;
      apply Nat.lt_add_of_pos_right_of_le; omega)).repr y) j =
    ((sDomain_basis 𝔽q β h_ℓ_add_R_rate (i := ⟨↑i, by omega⟩)
      (h_i := by simp only; omega)).repr x) ⟨j + k, by simp only; omega⟩

@[simp]
theorem dflatten_embedSum {m : ℕ} {n : Fin m → ℕ} {motive : (k : Fin (vsum n)) → Sort*}
    (v : (i : Fin m) → (j : Fin (n i)) → motive (embedSum i j)) (i : Fin m) (j : Fin (n i)) :
    dflatten (motive := motive) v (embedSum i j) = v i j

theorem eqPolynomial_zeroOne (r : σ → Fin 2) : (eqPolynomial r : MvPolynomial σ R) =
    ∏ i : σ, if r i = 0 then 1 - X i else X i

lemma rounds_sub_steps_lt : ℓ - ϑ < ℓ :=
  Nat.sub_lt (pos_of_neZero ℓ) (folding_steps_pos)

lemma fold_f_g
  {S : Finset ι} {φ : ι ↪ F} {k m : ℕ}
  {φ_0 : (indexPowT S φ 0) ↪ F} {φ_k : (indexPowT S φ k) ↪ F}
  [Fintype (indexPowT S φ 0)] [DecidableEq (indexPowT S φ 0)] [Smooth φ_0]
  [Fintype (indexPowT S φ k)] [DecidableEq (indexPowT S φ k)] [Smooth φ_k]
  [∀ i : ℕ, Neg (indexPowT S φ i)]
  (αs : Fin k → F) (hk : k ≤ m)
  (f : smoothCode φ_0 m) :
  let f_fun := (f : (indexPowT S φ 0) → F)
  let g := fold_k f_fun αs hk
  g ∈ smoothCode φ_k (m - k)

@[simp]
lemma dfoldrM'_succ {n : ℕ} {α : Fin (n + 1 + 1) → Type u}
    (f : (i : Fin (n + 1)) → α i.succ → m (α i.castSucc)) (x : α (last (n + 1))) :
    dfoldrM' (n + 1) α f x = (do
      let y ← dfoldrM' n (α ∘ succ) (fun i => f i.succ) x
      f 0 y)

theorem join_eq_bitvec_iff_fromNat {k : ℕ} (h_pos : k > 0) (x : ConcreteBTField k)
  (hi_btf lo_btf : ConcreteBTField (k - 1)) :
  x = 《 hi_btf, lo_btf 》 ↔
  (hi_btf = fromNat (k:=k - 1) (x.toNat >>> 2 ^ (k - 1)) ∧
  lo_btf = fromNat (k:=k - 1) (x.toNat &&& (2 ^ (2 ^ (k - 1)) - 1)))

theorem rightpad_eq_rightpad_max (l : List α) (n : Nat) :
    rightpad n unit l = rightpad (max n l.length) unit l

@[simp]
lemma OracleVerifier.id_toVerifier :
    (OracleVerifier.id : OracleVerifier oSpec Statement OStatement _ _ _).toVerifier =
      Verifier.id

theorem two_le_two_pow_n_plus_1 (n : ℕ) : 2 ≤ 2 ^ (n + 1)

@[simp]
theorem runWithOracle_failure (f : spec.FunctionType) :
    runWithOracle f (failure : OracleComp spec α) = none

theorem neg_add_cancel [LawfulBEq R] (p : UniPoly R) : -p + p = 0
</all_available_lemmas>

<local_ctx>
import ArkLib.Data.Nat.Bitwise

import Mathlib.RingTheory.MvPolynomial.Basic

import ToMathlib.General

import ArkLib.Data.Fin.BigOperators

import ArkLib.Data.List.Lemmas

import ArkLib.Data.Vector.Basic

@[reducible]
def MlPoly (R : Type*) (n : ℕ) := Vector R (2 ^ n) 

variable {R : Type*} {n : ℕ}

namespace MlPoly

section MlPolyInstances

end MlPolyInstances

section MlPolyMonomialBasisAndEvaluations

variable [CommRing R]

variable {S : Type*} [CommRing S]

variable {S : Type*} [CommRing S]

end MlPolyMonomialBasisAndEvaluations

end MlPoly

namespace MlPolyEval

section MlPolyEvalInstances

end MlPolyEvalInstances

section MlPolyLagrangeBasisAndEvaluations

variable [CommRing R]

variable {S : Type*} [CommRing S]

variable {S : Type*} [CommRing S]

end MlPolyLagrangeBasisAndEvaluations

end MlPolyEval

namespace MlPoly

variable {R : Type*} [AddCommGroup R]

@[inline] def monoToLagrangeLevel {n : ℕ} (j : Fin n) : Vector R (2 ^ n) → Vector R (2 ^ n) :=
  fun v =>
    let stride : ℕ := 2 ^ j.val    
    Vector.ofFn (fun i : Fin (2 ^ n) =>
      if (BitVec.ofFin i).getLsb j then
        v[i] + v[i - stride]'(Nat.sub_lt_of_lt i.isLt)
      else
        v[i])

@[inline] def lagrangeToMonoLevel {n : ℕ} (j : Fin n) : Vector R (2 ^ n) → Vector R (2 ^ n) :=
  fun v =>
    let stride : ℕ := 2 ^ j.val  
    Vector.ofFn (fun i : Fin (2 ^ n) =>
      if (BitVec.ofFin i).getLsb j then
        v[i] - v[i - stride]'(Nat.sub_lt_of_lt i.isLt)
      else
        v[i])

def forwardRange (n : ℕ) (r : Fin (n)) (l : Fin (r.val + 1)) : List (Fin n) :=
  let len := r.val - l.val + 1
  List.ofFn (fun (k : Fin len) =>
    let val := l.val + k.val
    have h_bound : val < n := by admit /- proof elided -/
  )

def monoToLagrange_segment (n : ℕ) (r : Fin n) (l : Fin (r.val + 1)) :
    Vector R (2 ^ n) → Vector R (2 ^ n) :=
  let range := forwardRange n r l
  (range.foldl (fun acc h => monoToLagrangeLevel h acc))

def lagrangeToMono_segment (n : ℕ) (r : Fin n) (l : Fin (r.val + 1)) :
    Vector R (2 ^ n) → Vector R (2 ^ n) :=
  let range := forwardRange n r l
  (range.foldr (fun h acc => lagrangeToMonoLevel h acc))
</local_ctx>

<target_theorem>
theorem mobius_apply_zeta_apply_eq_id (n : ℕ) [NeZero n] (r : Fin n) (l : Fin (r.val + 1))
    (v : Vector R (2 ^ n)) : lagrangeToMono_segment n r l (monoToLagrange_segment n r l v) = v :=
</target_theorem>

