Theorem: LO.Modal.Standard.reducible_K_KD (Logic/Modal/Standard/Deduction.lean)

State before:
α : Type u_1
inst✝ : DecidableEq α
⊢ 𝐊 ≤ₛ 𝐊𝐃
Tactic:
apply normal_reducible_subset
State after:
case hSubset
α : Type u_1
inst✝ : DecidableEq α
⊢ Ax(𝐊) ⊆ Ax(𝐊𝐃)

State before:
case hSubset
α : Type u_1
inst✝ : DecidableEq α
⊢ Ax(𝐊) ⊆ Ax(𝐊𝐃)
Tactic:
simp only [Set.subset_union_left]
State after:
no goals