-- Mathlib/.lake/packages/lean4/src/lean/Std/Tactic/BVDecide/Bitblast/BVExpr/Circuit/Impl/Operations/Add.lean
theorem go_decl_eq (aig : AIG α) (curr : Nat) (hcurr : curr ≤ w) (cin : AIG.Ref aig)
    (s : AIG.RefVec aig curr) (lhs rhs : AIG.RefVec aig w) :
    ∀ (idx : Nat) (h1) (h2),
        (go aig lhs rhs curr hcurr cin s).aig.decls[idx]'h2 = aig.decls[idx]'h1

Proof state:
case isTrue
α : Type
inst✝¹ : Hashable α
inst✝ : DecidableEq α
w : Nat
aig : AIG α
curr : Nat
hcurr : curr ≤ w
cin : aig.Ref
s : aig.RefVec curr
lhs rhs : aig.RefVec w
res : AIG.RefVecEntry α w
h✝ : curr < w
hgo :
  go (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).aig (lhs.cast ⋯) (rhs.cast ⋯)
      (curr + 1) ⋯ (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).cout
      ((s.cast ⋯).push (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).out) =
    res
⊢ ∀ (idx : Nat) (h1 : idx < aig.decls.size)
    (h2 :
      idx <
        (go (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).aig (lhs.cast ⋯)
                (rhs.cast ⋯) (curr + 1) ⋯
                (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).cout
                ((s.cast ⋯).push
                  (mkFullAdder aig
                      { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).out)).aig.decls.size),
    (go (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).aig (lhs.cast ⋯) (rhs.cast ⋯)
              (curr + 1) ⋯ (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).cout
              ((s.cast ⋯).push
                (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).out)).aig.decls[idx] =
      aig.decls[idx]

Tactic:
intros

Result:
case isTrue
α : Type
inst✝¹ : Hashable α
inst✝ : DecidableEq α
w : Nat
aig : AIG α
curr : Nat
hcurr : curr ≤ w
cin : aig.Ref
s : aig.RefVec curr
lhs rhs : aig.RefVec w
res : AIG.RefVecEntry α w
h✝ : curr < w
hgo :
  go (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).aig (lhs.cast ⋯) (rhs.cast ⋯)
      (curr + 1) ⋯ (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).cout
      ((s.cast ⋯).push (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).out) =
    res
idx✝ : Nat
h1✝ : idx✝ < aig.decls.size
h2✝ :
  idx✝ <
    (go (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).aig (lhs.cast ⋯) (rhs.cast ⋯)
            (curr + 1) ⋯ (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).cout
            ((s.cast ⋯).push
              (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).out)).aig.decls.size
⊢ (go (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).aig (lhs.cast ⋯) (rhs.cast ⋯)
            (curr + 1) ⋯ (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).cout
            ((s.cast ⋯).push
              (mkFullAdder aig { lhs := lhs.get curr h✝, rhs := rhs.get curr h✝, cin := cin }).out)).aig.decls[idx✝] =
    aig.decls[idx✝]

Proof state:
α : Type
inst✝¹ : Hashable α
inst✝ : DecidableEq α
w : Nat
aig : AIG α
curr : Nat
hcurr : curr ≤ w
cin : aig.Ref
s : aig.RefVec curr
lhs rhs : aig.RefVec w
res : AIG.RefVecEntry α w
hgo :
  (if hidx : curr < w then
      let lin := lhs.get curr hidx;
      let rin := rhs.get curr hidx;
      let res := mkFullAdder aig { lhs := lin, rhs := rin, cin := cin };
      let aig_1 := res.aig;
      let outRef := res.out;
      let carryRef := res.cout;
      let s := s.cast ⋯;
      let lhs := lhs.cast ⋯;
      let rhs := rhs.cast ⋯;
      let s := s.push outRef;
      go aig_1 lhs rhs (curr + 1) ⋯ carryRef s
    else
      let_fun hcurr := ⋯;
      { aig := aig, vec := hcurr ▸ s }) =
    res
⊢ ∀ (idx : Nat) (h1 : idx < aig.decls.size) (h2 : idx < res.aig.decls.size), res.aig.decls[idx] = aig.decls[idx]

Tactic:
dsimp only at hgo

Result:
α : Type
inst✝¹ : Hashable α
inst✝ : DecidableEq α
w : Nat
aig : AIG α
curr : Nat
hcurr : curr ≤ w
cin : aig.Ref
s : aig.RefVec curr
lhs rhs : aig.RefVec w
res : AIG.RefVecEntry α w
hgo :
  (if hidx : curr < w then
      go (mkFullAdder aig { lhs := lhs.get curr hidx, rhs := rhs.get curr hidx, cin := cin }).aig (lhs.cast ⋯)
        (rhs.cast ⋯) (curr + 1) ⋯
        (mkFullAdder aig { lhs := lhs.get curr hidx, rhs := rhs.get curr hidx, cin := cin }).cout
        ((s.cast ⋯).push (mkFullAdder aig { lhs := lhs.get curr hidx, rhs := rhs.get curr hidx, cin := cin }).out)
    else { aig := aig, vec := ⋯ ▸ s }) =
    res
⊢ ∀ (idx : Nat) (h1 : idx < aig.decls.size) (h2 : idx < res.aig.decls.size), res.aig.decls[idx] = aig.decls[idx]

Proof state:
α : Type
inst✝¹ : Hashable α
inst✝ : DecidableEq α
w : Nat
aig : AIG α
curr : Nat
hcurr : curr ≤ w
cin : aig.Ref
s : aig.RefVec curr
lhs rhs : aig.RefVec w
res : AIG.RefVecEntry α w
hgo : go aig lhs rhs curr hcurr cin s = res
⊢ ∀ (idx : Nat) (h1 : idx < aig.decls.size) (h2 : idx < res.aig.decls.size), res.aig.decls[idx] = aig.decls[idx]

Tactic:
unfold go at hgo

Result:
α : Type
inst✝¹ : Hashable α
inst✝ : DecidableEq α
w : Nat
aig : AIG α
curr : Nat
hcurr : curr ≤ w
cin : aig.Ref
s : aig.RefVec curr
lhs rhs : aig.RefVec w
res : AIG.RefVecEntry α w
hgo :
  (if hidx : curr < w then
      let lin := lhs.get curr hidx;
      let rin := rhs.get curr hidx;
      let res := mkFullAdder aig { lhs := lin, rhs := rin, cin := cin };
      let aig_1 := res.aig;
      let outRef := res.out;
      let carryRef := res.cout;
      let s := s.cast ⋯;
      let lhs := lhs.cast ⋯;
      let rhs := rhs.cast ⋯;
      let s := s.push outRef;
      go aig_1 lhs rhs (curr + 1) ⋯ carryRef s
    else
      let_fun hcurr := ⋯;
      { aig := aig, vec := hcurr ▸ s }) =
    res
⊢ ∀ (idx : Nat) (h1 : idx < aig.decls.size) (h2 : idx < res.aig.decls.size), res.aig.decls[idx] = aig.decls[idx]