diff --git a/ConNF.lean b/ConNF.lean
index 7708e543c7..fdeb3aec64 100644
--- a/ConNF.lean
+++ b/ConNF.lean
@@ -7,6 +7,7 @@ import ConNF.Aux.Set
 import ConNF.Aux.Transfer
 import ConNF.Aux.WellOrder
 import ConNF.Construction.Code
+import ConNF.Construction.NewModelData
 import ConNF.Counting.BaseCoding
 import ConNF.Counting.BaseCounting
 import ConNF.Counting.CodingFunction
diff --git a/ConNF/Construction/Code.lean b/ConNF/Construction/Code.lean
index a15a4b7f1a..7c5474a6d1 100644
--- a/ConNF/Construction/Code.lean
+++ b/ConNF/Construction/Code.lean
@@ -23,6 +23,7 @@ class TypedNearLitters (α : Λ) [ModelData α] [Position (Tangle α)] where
   typed : NearLitter → TSet α
   typed_injective : Function.Injective typed
   pos_le_pos_of_typed (N : NearLitter) (t : Tangle α) : t.set = typed N → pos N ≤ pos t
+  smul_typed (ρ : AllPerm α) (N : NearLitter) : ρ • typed N = typed (ρᵁ ↘. • N)
 
 export TypedNearLitters (typed)
 
@@ -194,6 +195,17 @@ theorem even_or_odd (c : Code) : c.Even ∨ c.Odd := by
       · exact .mk c d hd₁ hd
       · cases hd₂ hd
 
+@[simp]
+theorem not_even (c : Code) : ¬c.Even ↔ c.Odd := by
+  have := even_or_odd c
+  have := not_even_and_odd c
+  tauto
+
+@[simp]
+theorem not_odd (c : Code) : ¬c.Odd ↔ c.Even := by
+  have := not_even c
+  tauto
+
 inductive Represents : Rel Code Code
   | refl (c : Code) : c.Even → Represents c c
   | cloud (c d : Code) : c.Even → Cloud c d → Represents c d
diff --git a/ConNF/Construction/NewModelData.lean b/ConNF/Construction/NewModelData.lean
new file mode 100644
index 0000000000..89624a56fd
--- /dev/null
+++ b/ConNF/Construction/NewModelData.lean
@@ -0,0 +1,167 @@
+import ConNF.Construction.Code
+
+/-!
+# Construction of model data
+
+In this file, we construct model data at type `α`, given that it is defined at all types below `α`.
+
+## Main declarations
+
+* `ConNF.foo`: Something new.
+-/
+
+noncomputable section
+universe u
+
+open Cardinal Ordinal
+open scoped Pointwise
+
+namespace ConNF
+
+variable [Params.{u}] [Level] [LtData]
+
+@[ext]
+structure NewPerm : Type u where
+  sderiv : (β : TypeIndex) → [LtLevel β] → AllPerm β
+  smul_fuzz {β : TypeIndex} {γ : Λ} [LtLevel β] [LtLevel γ] (hβγ : β ≠ γ) (t : Tangle β) :
+    (sderiv γ)ᵁ ↘. • fuzz hβγ t = fuzz hβγ (sderiv β • t)
+
+instance : Mul NewPerm where
+  mul ρ₁ ρ₂ := ⟨λ β _ ↦ ρ₁.sderiv β * ρ₂.sderiv β, by
+    intro β γ _ _ hβγ t
+    simp only [allPermForget_mul, mul_smul, Tree.mul_sderivBot, NewPerm.smul_fuzz]⟩
+
+instance : One NewPerm where
+  one := ⟨λ _ _ ↦ 1, by
+    intro β γ _ _ hβγ t
+    simp only [allPermForget_one, one_smul, Tree.one_sderivBot]⟩
+
+instance : Inv NewPerm where
+  inv ρ := ⟨λ β _ ↦ (ρ.sderiv β)⁻¹, by
+    intro β γ _ _ hβγ t
+    simp only [allPermForget_inv, Tree.inv_sderivBot, inv_smul_eq_iff, NewPerm.smul_fuzz,
+      smul_inv_smul]⟩
+
+@[simp]
+theorem mul_sderiv (ρ₁ ρ₂ : NewPerm) (β : TypeIndex) [LtLevel β] :
+    (ρ₁ * ρ₂).sderiv β = ρ₁.sderiv β * ρ₂.sderiv β :=
+  rfl
+
+@[simp]
+theorem one_sderiv (β : TypeIndex) [LtLevel β] :
+    (1 : NewPerm).sderiv β = 1 :=
+  rfl
+
+@[simp]
+theorem inv_sderiv (ρ : NewPerm) (β : TypeIndex) [LtLevel β] :
+    ρ⁻¹.sderiv β = (ρ.sderiv β)⁻¹ :=
+  rfl
+
+instance : Group NewPerm where
+  mul_assoc ρ₁ ρ₂ ρ₃ := by
+    ext β : 3
+    simp only [mul_sderiv, mul_assoc]
+  one_mul ρ := by
+    ext β : 3
+    simp only [mul_sderiv, one_mul, one_sderiv]
+  mul_one ρ := by
+    ext β : 3
+    simp only [mul_sderiv, mul_one, one_sderiv]
+  inv_mul_cancel ρ := by
+    ext β : 3
+    simp only [mul_sderiv, inv_sderiv, inv_mul_cancel, one_sderiv]
+
+instance : SMul NewPerm Code where
+  smul ρ c := ⟨c.β, ρ.sderiv c.β • c.s, Set.smul_set_nonempty.mpr c.hs⟩
+
+@[simp]
+theorem NewPerm.smul_mk (ρ : NewPerm) (β : TypeIndex) [LtLevel β]
+    (s : Set (TSet β)) (hs : s.Nonempty) :
+    ρ • Code.mk β s hs = ⟨β, ρ.sderiv β • s, Set.smul_set_nonempty.mpr hs⟩ :=
+  rfl
+
+instance : MulAction NewPerm Code where
+  one_smul := by
+    rintro ⟨β, s, hs⟩
+    simp only [NewPerm.smul_mk, one_sderiv, one_smul]
+  mul_smul := by
+    rintro ρ₁ ρ₂ ⟨β, s, hs⟩
+    simp only [NewPerm.smul_mk, mul_sderiv, mul_smul]
+
+theorem Cloud.smul {c d : Code} (h : Cloud c d) (ρ : NewPerm) :
+    Cloud (ρ • c) (ρ • d) := by
+  obtain ⟨β, γ, hβγ, s, hs⟩ := h
+  convert Cloud.mk β γ hβγ (ρ.sderiv β • s) (Set.smul_set_nonempty.mpr hs) using 1
+  rw [NewPerm.smul_mk, Code.mk.injEq, heq_eq_eq]
+  use rfl
+  ext x
+  constructor
+  · rintro ⟨y, ⟨N, ⟨t, ht, hN⟩, rfl⟩, rfl⟩
+    refine ⟨(ρ.sderiv γ)ᵁ ↘. • N, ⟨ρ.sderiv β • t, ?_, ?_⟩, ?_⟩
+    · rwa [Tangle.smul_set, Set.smul_mem_smul_set_iff]
+    · rw [BasePerm.smul_nearLitter_litter, hN, NewPerm.smul_fuzz]
+    · rw [← TypedNearLitters.smul_typed]
+  · rintro ⟨N, ⟨t, ⟨x, hxs, hxt⟩, hN⟩, rfl⟩
+    refine ⟨(ρ.sderiv γ)⁻¹ • typed N,
+        ⟨(ρ.sderiv γ)ᵁ⁻¹ ↘. • N, ⟨(ρ.sderiv β)⁻¹ • t, ?_, ?_⟩, ?_⟩, ?_⟩
+    · rwa [Tangle.smul_set, ← hxt, inv_smul_smul]
+    · rw [Tree.inv_sderivBot, BasePerm.smul_nearLitter_litter, inv_smul_eq_iff,
+        NewPerm.smul_fuzz, smul_inv_smul, hN]
+    · rw [Tree.inv_sderivBot, TypedNearLitters.smul_typed, allPermForget_inv, Tree.inv_sderivBot]
+    · simp only [smul_inv_smul]
+
+@[simp]
+theorem Code.smul_even {c : Code} (ρ : NewPerm) :
+    (ρ • c).Even ↔ c.Even := by
+  induction c using cloud_wf.induction
+  case h c ih =>
+    constructor
+    · rintro ⟨_, hc⟩
+      constructor
+      intro d hd
+      have := hc (ρ • d) (hd.smul ρ)
+      by_contra hd'
+      rw [not_odd, ← ih d hd] at hd'
+      exact not_even_and_odd _ ⟨hd', this⟩
+    · rintro ⟨_, hc⟩
+      constructor
+      intro d hd
+      have hc' := hc (ρ⁻¹ • d) ?_
+      · have ih' := ih (ρ⁻¹ • d) ?_
+        · rw [smul_inv_smul] at ih'
+          by_contra hd'
+          rw [not_odd, ih'] at hd'
+          exact not_even_and_odd _ ⟨hd', hc'⟩
+        · have := hd.smul ρ⁻¹
+          rwa [inv_smul_smul] at this
+      · have := hd.smul ρ⁻¹
+        rwa [inv_smul_smul] at this
+
+theorem Represents.smul {c d : Code} (h : Represents c d) (ρ : NewPerm) :
+    Represents (ρ • c) (ρ • d) := by
+  obtain (⟨_, h⟩ | ⟨_, _, hc, hcd⟩) := h
+  · refine .refl _ ?_
+    rwa [Code.smul_even]
+  · refine .cloud _ _ ?_ ?_
+    · rwa [Code.smul_even]
+    · exact hcd.smul ρ
+
+def Path.untop {β γ : TypeIndex} (A : β ↝ γ) (h : β ≠ γ) :
+    ((δ : {δ : TypeIndex // δ < β}) × δ ↝ γ) :=
+  A.recScoderiv (motive := λ ε _ ↦ ε ≠ γ → ((δ : {δ : TypeIndex // δ < ε}) × δ ↝ γ))
+    (λ h ↦ (h rfl).elim) (λ ε ζ B hζ _ h ↦ ⟨⟨ζ, hζ⟩, B⟩) h
+
+def Path.recTop {β δ : TypeIndex} (hβδ : δ < β) {motive : Sort _}
+    (scoderiv : ∀ γ (h : γ < β), γ ↝ δ → motive)
+    {γ : TypeIndex} (A : β ↝ δ) : motive :=
+  sorry
+
+-- instance : SuperU NewPerm (StrPerm α) where
+--   superU ρ := λ A ↦ A.recScoderiv (motive := λ β _ ↦ BasePerm) _ (λ β γ B hγβ _ ↦ _)
+
+structure NewSet : Type u where
+  c : Code
+  hc : c.Even
+  hS : ∃ S : Support α, ∀ ρ : NewPerm, ρᵁ • S = S → ρ • c = c
+
+end ConNF
diff --git a/ConNF/Setup/Tree.lean b/ConNF/Setup/Tree.lean
index 2d681a8834..7c7a757e3e 100644
--- a/ConNF/Setup/Tree.lean
+++ b/ConNF/Setup/Tree.lean
@@ -84,6 +84,11 @@ theorem one_sderiv [Group X] (h : β < α) :
     (1 : Tree X α) ↘ h = 1 :=
   rfl
 
+@[simp]
+theorem one_sderivBot [Group X] :
+    (1 : Tree X α) ↘. = 1 :=
+  rfl
+
 @[simp]
 theorem mul_apply [Group X] (T₁ T₂ : Tree X α) (A : α ↝ ⊥) :
     (T₁ * T₂) A = T₁ A * T₂ A :=
@@ -94,29 +99,39 @@ theorem mul_sderiv [Group X] (T₁ T₂ : Tree X α) (h : β < α) :
     (T₁ * T₂) ↘ h = T₁ ↘ h * T₂ ↘ h :=
   rfl
 
+@[simp]
+theorem mul_sderivBot [Group X] (T₁ T₂ : Tree X α) :
+    (T₁ * T₂) ↘. = T₁ ↘. * T₂ ↘. :=
+  rfl
+
 @[simp]
 theorem inv_apply [Group X] (T : Tree X α) (A : α ↝ ⊥) :
     T⁻¹ A = (T A)⁻¹ :=
   rfl
 
 @[simp]
-theorem npow_apply [Group X] (T : Tree X α) (A : α ↝ ⊥) (n : ℕ) :
-    (T ^ n) A = (T A) ^ n :=
+theorem inv_deriv [Group X] (T : Tree X α) (A : α ↝ β) :
+    T⁻¹ ⇘ A = (T ⇘ A)⁻¹ :=
   rfl
 
 @[simp]
-theorem zpow_apply [Group X] (T : Tree X α) (A : α ↝ ⊥) (n : ℤ) :
-    (T ^ n) A = (T A) ^ n :=
+theorem inv_sderiv [Group X] (T : Tree X α) (h : β < α) :
+    T⁻¹ ↘ h = (T ↘ h)⁻¹ :=
   rfl
 
 @[simp]
-theorem inv_deriv [Group X] (T : Tree X α) (A : α ↝ β) :
-    T⁻¹ ⇘ A = (T ⇘ A)⁻¹ :=
+theorem inv_sderivBot [Group X] (T : Tree X α) :
+    T⁻¹ ↘. = (T ↘.)⁻¹ :=
   rfl
 
 @[simp]
-theorem inv_sderiv [Group X] (T : Tree X α) (h : β < α) :
-    T⁻¹ ↘ h = (T ↘ h)⁻¹ :=
+theorem npow_apply [Group X] (T : Tree X α) (A : α ↝ ⊥) (n : ℕ) :
+    (T ^ n) A = (T A) ^ n :=
+  rfl
+
+@[simp]
+theorem zpow_apply [Group X] (T : Tree X α) (A : α ↝ ⊥) (n : ℤ) :
+    (T ^ n) A = (T A) ^ n :=
   rfl
 
 /-- The partial order on the type of `α`-trees of `X` is given by "branchwise" comparison. -/