Theorem: Cardinal.mk_subtype_le_of_countable_eventually_mem
File: Mathlib/SetTheory/Cardinal/CountableCover.lean

tactic: suffices #(ULift.down.{v} ⁻¹' t) ≤ Cardinal.lift.{v, u} a by simpa
state_before: α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
⊢ #↑t ≤ a
state_after: α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
⊢ #↑(ULift.down ⁻¹' t) ≤ lift.{v, u} a

tactic: let l' : Filter (ULift.{u} ι) := Filter.map ULift.up l
state_before: α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
⊢ #↑(ULift.down ⁻¹' t) ≤ lift.{v, u} a
state_after: α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
⊢ #↑(ULift.down ⁻¹' t) ≤ lift.{v, u} a

tactic: have : NeBot l' := map_neBot
state_before: α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
⊢ #↑(ULift.down ⁻¹' t) ≤ lift.{v, u} a
state_after: α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
⊢ #↑(ULift.down ⁻¹' t) ≤ lift.{v, u} a

tactic: apply mk_subtype_le_of_countable_eventually_mem_aux (ι := ULift.{u} ι) (l := l') (f := g)
state_before: α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
⊢ #↑(ULift.down ⁻¹' t) ≤ lift.{v, u} a
state_after: case ht
α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
⊢ ∀ x ∈ ULift.down ⁻¹' t, ∀ᶠ (i : ULift.{u, v} ι) in l', x ∈ g i

case h'f
α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
⊢ ∀ (i : ULift.{u, v} ι), #↑(g i) ≤ lift.{v, u} a

tactic: simpa
state_before: α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
this : #↑(ULift.down ⁻¹' t) ≤ lift.{v, u} a
⊢ #↑t ≤ a
state_after: no goals

tactic: intro x hx
state_before: case ht
α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
⊢ ∀ x ∈ ULift.down ⁻¹' t, ∀ᶠ (i : ULift.{u, v} ι) in l', x ∈ g i
state_after: case ht
α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
x : ULift.{v, u} α
hx : x ∈ ULift.down ⁻¹' t
⊢ ∀ᶠ (i : ULift.{u, v} ι) in l', x ∈ g i

tactic: simpa only [Function.comp_apply, mem_preimage, eventually_map] using ht _ hx
state_before: case ht
α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
x : ULift.{v, u} α
hx : x ∈ ULift.down ⁻¹' t
⊢ ∀ᶠ (i : ULift.{u, v} ι) in l', x ∈ g i
state_after: no goals

tactic: intro i
state_before: case h'f
α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
⊢ ∀ (i : ULift.{u, v} ι), #↑(g i) ≤ lift.{v, u} a
state_after: case h'f
α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
i : ULift.{u, v} ι
⊢ #↑(g i) ≤ lift.{v, u} a

tactic: simpa [g] using h'f i.down
state_before: case h'f
α : Type u
ι : Type v
a : Cardinal.{u}
inst✝¹ : Countable ι
f : ι → Set α
l : Filter ι
inst✝ : l.NeBot
t : Set α
ht : ∀ x ∈ t, ∀ᶠ (i : ι) in l, x ∈ f i
h'f : ∀ (i : ι), #↑(f i) ≤ a
g : ULift.{u, v} ι → Set (ULift.{v, u} α) := (fun x => ULift.down ⁻¹' x) ∘ f ∘ ULift.down
l' : Filter (ULift.{u, v} ι) := Filter.map ULift.up l
this : l'.NeBot
i : ULift.{u, v} ι
⊢ #↑(g i) ≤ lift.{v, u} a
state_after: no goals