theorem copy_eq (e : PartialEquiv α β) (f : α → β) (hf : ⇑e = f) (g : β → α) (hg : ⇑e.symm = g)
    (s : Set α) (hs : e.source = s) (t : Set β) (ht : e.target = t) :
    e.copy f hf g hg s hs t ht = e := by
  substs f g s t
  cases e
  

Proof state:
case mk
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
e : PartialEquiv α β
e' : PartialEquiv β γ
toFun✝ : α → β
invFun✝ : β → α
source✝ : Set α
target✝ : Set β
map_source'✝ : ∀ ⦃x : α⦄, x ∈ source✝ → toFun✝ x ∈ target✝
map_target'✝ : ∀ ⦃x : β⦄, x ∈ target✝ → invFun✝ x ∈ source✝
left_inv'✝ : ∀ ⦃x : α⦄, x ∈ source✝ → invFun✝ (toFun✝ x) = x
right_inv'✝ : ∀ ⦃x : β⦄, x ∈ target✝ → toFun✝ (invFun✝ x) = x
⊢ copy
      { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
        map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }
      ↑{ toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
          map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }
      (_ :
        ↑{ toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
              map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ } =
          ↑{ toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
              map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ })
      ↑(PartialEquiv.symm
          { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
            map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ })
      (_ :
        ↑(PartialEquiv.symm
              { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
                map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }) =
          ↑(PartialEquiv.symm
              { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
                map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }))
      { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
          map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }.source
      (_ :
        { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
              map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }.source =
          { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
              map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }.source)
      { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
          map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }.target
      (_ :
        { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
              map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }.target =
          { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
              map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }.target) =
    { toFun := toFun✝, invFun := invFun✝, source := source✝, target := target✝, map_source' := map_source'✝,
      map_target' := map_target'✝, left_inv' := left_inv'✝, right_inv' := right_inv'✝ }

Next tactic:
rfl