clear h hHd
α : Type u_1
inst✝ : SizeOf α
f : α → Bool
hd : α
tl : List α
ih : ¬filter f tl = tl → sizeOf (filter f tl) < sizeOf tl
h :
  ¬(match f hd with
      | true => hd :: filter f tl
      | false => filter f tl) =
      hd :: tl
x✝ : Bool
hHd : f hd = false
⊢ sizeOf (filter f tl) < 1 + sizeOf hd + sizeOf tl
α : Type u_1
inst✝ : SizeOf α
f : α → Bool
hd : α
tl : List α
ih : ¬filter f tl = tl → sizeOf (filter f tl) < sizeOf tl
x✝ : Bool
⊢ sizeOf (filter f tl) < 1 + sizeOf hd + sizeOf tl