exact congOrLeft (fun hp => @ih (drop 0 (take j l)) 0 j (by simp [hp]) rfl) hp
case cons.succ.zero
t : Prop
l : List Prop
ih : ∀ {ps : List Prop} {i j : Nat}, orN ps → ps = drop i (take j l) → orN l
ps : List Prop
j : Nat
hps : ps = drop 0 (t :: take j l)
hp : t ∨ orN (take j l)
⊢ t ∨ orN l
no goals