intro a b ma mb
case isTrue.w
g : CNF Nat
h : ∃ a, mem a g
⊢ ∀ {a b : Nat},
    mem a g →
      mem b g →
        ((if w : a < g.numLiterals then ⟨a, w⟩ else ⟨0, ⋯⟩) = if w : b < g.numLiterals then ⟨b, w⟩ else ⟨0, ⋯⟩) → a = b
case isTrue.w
g : CNF Nat
h : ∃ a, mem a g
a b : Nat
ma : mem a g
mb : mem b g
⊢ ((if w : a < g.numLiterals then ⟨a, w⟩ else ⟨0, ⋯⟩) = if w : b < g.numLiterals then ⟨b, w⟩ else ⟨0, ⋯⟩) → a = b