Theorem: IntuitionisticPropositionalLogic.ProvableFrom.insert (GlimpseOfLean/Solutions/Topics/IntuitionisticPropositionalLogic.lean)

State before:
H : Type ?u.36542
inst✝ : HeytingAlgebra H
v : Variable → H
A B : Formula
Γ Δ : Set Formula
h : Γ ⊢ A
⊢ Insert.insert B Γ ⊢ A
Tactic:
apply weakening h
State after:
H : Type ?u.36542
inst✝ : HeytingAlgebra H
v : Variable → H
A B : Formula
Γ Δ : Set Formula
h : Γ ⊢ A
⊢ Γ ⊆ Insert.insert B Γ

State before:
H : Type ?u.36542
inst✝ : HeytingAlgebra H
v : Variable → H
A B : Formula
Γ Δ : Set Formula
h : Γ ⊢ A
⊢ Γ ⊆ Insert.insert B Γ
Tactic:
exact subset_insert B Γ
State after:
no goals