rw [←sp, nil']
α : Type
inst✝ : DecidableEq α
start : List (α × Bool)
a : α
b : Bool
reduced_start : Reduced start
nilP : ¬start = []
cancP : List.getLast start nilP = (a, b)⁻¹
nil' : List.dropLast start = []
sp : List.dropLast start ++ [List.getLast start nilP] = start := split_drop start nilP
⊢ [(a, !b)] = start
α : Type
inst✝ : DecidableEq α
start : List (α × Bool)
a : α
b : Bool
reduced_start : Reduced start
nilP : ¬start = []
cancP : List.getLast start nilP = (a, b)⁻¹
nil' : List.dropLast start = []
sp : List.dropLast start ++ [List.getLast start nilP] = start := split_drop start nilP
⊢ [(a, !b)] = [] ++ [List.getLast start nilP]