Array.PrefixTable.valid

theorem Array.PrefixTable.valid : ∀ {α : Type u_1} (self : Array.PrefixTable α) {i : ℕ} (h : i < self.size), self.toArray[i].2 ≤ i

This theorem states a validity condition for an array that is used in proofs of termination. Specifically, for an array of type `PrefixTable α`, for every index `i` that is less than the size of this array (`i < self.size`), the second element (`toArray[i].2`) of the array entry at that index is guaranteed to be less than or equal to `i`. This property is crucial for establishing certain termination conditions in recursive algorithms.

More concisely: For every index `i` less than the size of a `PrefixTable α` array `self`, the second element of its `i`-th entry `toArray[i]` satisfies `toArray[i].2 ≤ i`.