aesop
φ1 φ2 : Formula
IH1 : ∀ n ∈ voc φ1, n < freshVarForm φ1
IH2 : ∀ n ∈ voc φ2, n < freshVarForm φ2
⊢ ∀ (n : ℕ), n ∈ vocabOfFormula φ1 ∨ n ∈ vocabOfFormula φ2 → n < freshVarForm φ1 ∨ n < freshVarForm φ2
no goals