subst l
case intro
α : Formula
L R : Finset Formula
α_in_L : α ∈ L
c : TNode
Lcond' : Finset Formula
L_cond_in : Lcond' ⊆ L
ress : List (Finset Formula)
orule' : OneSidedLocalRule Lcond' ress
φ : Formula
c_in : ∃ a ∈ ress, (L \ Lcond' ∪ a, R) = c
l : φ = α
r : ~φ = α
⊢ α ∈ c.1
case intro
L R : Finset Formula
c : TNode
Lcond' : Finset Formula
L_cond_in : Lcond' ⊆ L
ress : List (Finset Formula)
orule' : OneSidedLocalRule Lcond' ress
φ : Formula
c_in : ∃ a ∈ ress, (L \ Lcond' ∪ a, R) = c
α_in_L : φ ∈ L
r : ~φ = φ
⊢ φ ∈ c.1