subst c_in
α : Formula
R L : Finset Formula
α_in_R : α ∈ R
c : TNode
φ ψ φ' ψ' : Formula
precond_eq : φ⋀ψ = α
R_cond_in : φ'⋀ψ' ∈ R
c_in : c = (L, insert φ' (insert ψ' (R.erase (φ'⋀ψ'))))
⊢ (α = φ' ∨ α = ψ' ∨ ¬α = φ'⋀ψ') ∨ {φ, ψ} ⊆ insert φ' (insert ψ' (R.erase (φ'⋀ψ')))
α : Formula
R L : Finset Formula
α_in_R : α ∈ R
φ ψ φ' ψ' : Formula
precond_eq : φ⋀ψ = α
R_cond_in : φ'⋀ψ' ∈ R
⊢ (α = φ' ∨ α = ψ' ∨ ¬α = φ'⋀ψ') ∨ {φ, ψ} ⊆ insert φ' (insert ψ' (R.erase (φ'⋀ψ')))