case nil.nil | cons.nil => simp_all;
α : Type u_1
Ax : AxiomSet α
head✝ : Axioms.Geach.Taple
tail✝ : List Axioms.Geach.Taple
tail_ih✝ : ∀ {l₂ : List Axioms.Geach.Taple}, tail✝ ⊆ l₂ → 𝗚𝗲(tail✝) ⊆ 𝗚𝗲(l₂)
h : head✝ :: tail✝ ⊆ []
⊢ 𝗚𝗲(head✝ :: tail✝) ⊆ 𝗚𝗲([])
no goals