Theorem: frontier_le_subset_eq
File: Mathlib/Topology/Order/OrderClosed.lean

Proof steps:
state_before: α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
⊢ frontier {b | f b ≤ g b} ⊆ {b | f b = g b}
state_after: α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
⊢ {b | f b ≤ g b} ∩ closure {b | f b ≤ g b}ᶜ ⊆ {b | f b = g b}
tactic: rw [frontier_eq_closure_inter_closure, closure_le_eq hf hg]
state_before: α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
⊢ {b | f b ≤ g b} ∩ closure {b | f b ≤ g b}ᶜ ⊆ {b | f b = g b}
state_after: case intro
α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
b : β
hb₁ : b ∈ {b | f b ≤ g b}
hb₂ : b ∈ closure {b | f b ≤ g b}ᶜ
⊢ b ∈ {b | f b = g b}
tactic: rintro b ⟨hb₁, hb₂⟩
state_before: case intro
α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
b : β
hb₁ : b ∈ {b | f b ≤ g b}
hb₂ : b ∈ closure {b | f b ≤ g b}ᶜ
⊢ b ∈ {b | f b = g b}
state_after: case intro
α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
b : β
hb₁ : b ∈ {b | f b ≤ g b}
hb₂ : b ∈ closure {b | f b ≤ g b}ᶜ
⊢ b ∈ closure {b | g b < f b}
tactic: refine le_antisymm hb₁ (closure_lt_subset_le hg hf ?_)
state_before: case intro
α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
b : β
hb₁ : b ∈ {b | f b ≤ g b}
hb₂ : b ∈ closure {b | f b ≤ g b}ᶜ
⊢ b ∈ closure {b | g b < f b}
state_after: case h.e'_5.h.e'_3
α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
b : β
hb₁ : b ∈ {b | f b ≤ g b}
hb₂ : b ∈ closure {b | f b ≤ g b}ᶜ
⊢ {b | g b < f b} = {b | f b ≤ g b}ᶜ
tactic: convert hb₂ using 2
state_before: case h.e'_5.h.e'_3
α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
b : β
hb₁ : b ∈ {b | f b ≤ g b}
hb₂ : b ∈ closure {b | f b ≤ g b}ᶜ
⊢ {b | g b < f b} = {b | f b ≤ g b}ᶜ
state_after: case h.e'_5.h.e'_3
α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
b : β
hb₁ : b ∈ {b | f b ≤ g b}
hb₂ : b ∈ closure {b | f b ≤ g b}ᶜ
⊢ {b | ¬f b ≤ g b} = {b | f b ≤ g b}ᶜ
tactic: simp only [not_le.symm]
state_before: case h.e'_5.h.e'_3
α : Type u
β : Type v
γ : Type w
inst✝³ : TopologicalSpace α
inst✝² : LinearOrder α
inst✝¹ : OrderClosedTopology α
f g : β → α
inst✝ : TopologicalSpace β
hf : Continuous f
hg : Continuous g
b : β
hb₁ : b ∈ {b | f b ≤ g b}
hb₂ : b ∈ closure {b | f b ≤ g b}ᶜ
⊢ {b | ¬f b ≤ g b} = {b | f b ≤ g b}ᶜ
state_after: no goals
tactic: rfl