rcases nv with ⟨nv₁, nv₂, e⟩
θ t✝ : Sinf_term
a✝ : NoVars t✝
nv : Ø ⋁ t✝ =ₛ t✝
⊢ Ø ⋁ t✝↗ =ₛ t✝↗
case S_axiom
θ t✝ : Sinf_term
a✝ nv₁ nv₂ : NoVars t✝
e : Sinf_const.eval (Sinf_const.coerce t✝ nv₁) = Sinf_const.eval (Sinf_const.coerce t✝ nv₂)
⊢ Ø ⋁ t✝↗ =ₛ t✝↗