rw [tautImp_iff_comboNotUnsat]
case h.right.left
φ ψ : Formula
hyp : φ⊨ψ
X : TNode := ([φ], [~ψ], none)
ctX : ClosedTableau ([], []) X
θ : Formula
this : ¬satisfiable ((~θ) :: X.left)
⊢ φ⊨θ
case h.right.left
φ ψ : Formula
hyp : φ⊨ψ
X : TNode := ([φ], [~ψ], none)
ctX : ClosedTableau ([], []) X
θ : Formula
this : ¬satisfiable ((~θ) :: X.left)
⊢ ¬satisfiable [φ, ~θ]