cases k
case zero
p : Fin 0 → Prop
inst : DecidablePred p
k : Fin 0
i : { i // p i }
⊢ decodeSubtype p k = i ↔ encodeSubtype p i = k
case zero.mk
p : Fin 0 → Prop
inst : DecidablePred p
i : { i // p i }
val✝ : Nat
isLt✝ : val✝ < 0
⊢ decodeSubtype p ⟨val✝, isLt✝⟩ = i ↔ encodeSubtype p i = ⟨val✝, isLt✝⟩