aesop
case con
α : Formula
L R : Finset Formula
α_in_L : α ∈ L
c : TNode
φ ψ : Formula
precond_eq : ~(φ⋀ψ) = α
φ✝ ψ✝ : Formula
L_cond_in : {φ✝⋀ψ✝} ⊆ L
c_in : ∃ a ∈ [{φ✝, ψ✝}], (L \ {φ✝⋀ψ✝} ∪ a, R) = c
⊢ α ∈ c.1 ∨ ~φ ∈ c.1 ∨ ~ψ ∈ c.1
no goals