-- Mathlib/Order/CompactlyGenerated/Basic.lean
theorem sSupIndep_iff_finite {s : Set α} :
    sSupIndep s ↔
      ∀ t : Finset α, ↑t ⊆ s → sSupIndep (↑t : Set α) :=
  ⟨fun hs _ ht => hs.mono ht, fun h a ha => by
    rw [disjoint_iff, inf_sSup_eq_iSup_inf_sup_finset, iSup_eq_bot]
    intro t
    rw [iSup_eq_bot, Finset.sup_id_eq_sSup]
    intro ht
    classical
      have h' := (h (insert a t) ?_ (t.mem_insert_self a)).eq_bot
      · rwa [Finset.coe_insert, Set.insert_diff_self_of_not_mem] at h'
        exact fun con => ((Set.mem_diff a).1 (ht con)).2 (Set.mem_singleton a)
      · rw [Finset.coe_insert, Set.insert_subset_iff]
        exact ⟨ha, Set.Subset.trans ht diff_subset⟩⟩

Proof state:
case refine_1
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
⊢ a ∈ s ∧ ↑t ⊆ s

Tactic:
exact ⟨ha, Set.Subset.trans ht diff_subset⟩

Result:
no goals

Proof state:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
⊢ ↑t ⊆ s \ {a} → a ⊓ sSup ↑t = ⊥

Tactic:
intro ht

Result:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
⊢ a ⊓ sSup ↑t = ⊥

Proof state:
case refine_1
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
⊢ ↑(insert a t) ⊆ s

Tactic:
rw [Finset.coe_insert, Set.insert_subset_iff]

Result:
case refine_1
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
⊢ a ∈ s ∧ ↑t ⊆ s

Proof state:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
⊢ Disjoint a (sSup (s \ {a}))

Tactic:
rw [disjoint_iff, inf_sSup_eq_iSup_inf_sup_finset, iSup_eq_bot]

Result:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
⊢ ∀ (i : Finset α), ⨆ (_ : ↑i ⊆ s \ {a}), a ⊓ i.sup id = ⊥

Proof state:
case refine_2
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
h' : a ⊓ sSup (↑(insert a t) \ {a}) = ⊥
⊢ a ⊓ sSup ↑t = ⊥

Tactic:
rwa [Finset.coe_insert, Set.insert_diff_self_of_not_mem] at h'

Result:
case refine_2
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
h' : a ⊓ sSup (insert a ↑t \ {a}) = ⊥
⊢ a ∉ ↑t

Proof state:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
⊢ a ⊓ sSup ↑t = ⊥

Tactic:
have h' := (h (insert a t) ?_ (t.mem_insert_self a)).eq_bot

Result:
case refine_2
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
h' : a ⊓ sSup (↑(insert a t) \ {a}) = ⊥
⊢ a ⊓ sSup ↑t = ⊥

case refine_1
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
⊢ ↑(insert a t) ⊆ s

Proof state:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
⊢ ∀ (i : Finset α), ⨆ (_ : ↑i ⊆ s \ {a}), a ⊓ i.sup id = ⊥

Tactic:
intro t

Result:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
⊢ ⨆ (_ : ↑t ⊆ s \ {a}), a ⊓ t.sup id = ⊥

Proof state:
case refine_2
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
ht : ↑t ⊆ s \ {a}
h' : a ⊓ sSup (insert a ↑t \ {a}) = ⊥
⊢ a ∉ ↑t

Tactic:
exact fun con => ((Set.mem_diff a).1 (ht con)).2 (Set.mem_singleton a)

Result:
no goals

Proof state:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
⊢ ⨆ (_ : ↑t ⊆ s \ {a}), a ⊓ t.sup id = ⊥

Tactic:
rw [iSup_eq_bot, Finset.sup_id_eq_sSup]

Result:
α : Type u_2
inst✝¹ : CompleteLattice α
inst✝ : IsCompactlyGenerated α
s : Set α
h : ∀ (t : Finset α), ↑t ⊆ s → sSupIndep ↑t
a : α
ha : a ∈ s
t : Finset α
⊢ ↑t ⊆ s \ {a} → a ⊓ sSup ↑t = ⊥