Verifiable deletion and machine unlearning: "deleted the source record" ≠ "the model forgot" — and proving it forgot is harder still
In one sentence once memorization is in the weights, deleting the source doesn't make it vanish). Machine unlearning aims to make the model "behave as if it never saw that record." Two hard parts: ① how to actually forget (exact unlearning ≈ equivalent retraining, expensive; approximate unlearning is fast but unguaranteed); ② how to prove it forgot (verifiable deletion) — the piece engineering most lacks.