. simp[LRAT.Clause.toList, LRAT.DefaultClause.toList]
  simp[CNF.Clause.convertLRAT'] at h
  exact CNF.Clause.mem_lrat_of_mem clause hlit1 h
case intro.intro.left
n : Nat
lratClause : LRAT.DefaultClause n
assign : PosFin n → Bool
clause : Clause (PosFin n)
h : clause.convertLRAT' = some lratClause
lit : PosFin n × Bool
hlit1 : lit ∈ clause
hlit2 : (assign lit.fst == lit.snd) = true
⊢ (lit.fst, lit.snd) ∈ LRAT.Clause.toList lratClause

case intro.intro.right
n : Nat
lratClause : LRAT.DefaultClause n
assign : PosFin n → Bool
clause : Clause (PosFin n)
h : clause.convertLRAT' = some lratClause
lit : PosFin n × Bool
hlit1 : lit ∈ clause
hlit2 : (assign lit.fst == lit.snd) = true
⊢ assign (lit.fst, lit.snd).fst = (lit.fst, lit.snd).snd
case intro.intro.right
n : Nat
lratClause : LRAT.DefaultClause n
assign : PosFin n → Bool
clause : Clause (PosFin n)
h : clause.convertLRAT' = some lratClause
lit : PosFin n × Bool
hlit1 : lit ∈ clause
hlit2 : (assign lit.fst == lit.snd) = true
⊢ assign (lit.fst, lit.snd).fst = (lit.fst, lit.snd).snd