rcases Clause.maxLiteral_eq_some_of_mem clause hclause2 with ⟨localMax, hlocal⟩
case intro.intro
maxLit : Nat
c : CNF Nat
h : c.maxLiteral = some maxLit
lit : Nat
clause : Clause Nat
hclause1 : clause ∈ c
hclause2 : Clause.mem lit clause
⊢ lit ≤ maxLit
case intro.intro.intro
maxLit : Nat
c : CNF Nat
h : c.maxLiteral = some maxLit
lit : Nat
clause : Clause Nat
hclause1 : clause ∈ c
hclause2 : Clause.mem lit clause
localMax : Nat
hlocal : clause.maxLiteral = some localMax
⊢ lit ≤ maxLit