Co-op and condo boards across New York City rejoiced when Local Law 18 went into effect last fall — and promptly cut down on illegal short-term apartment rentals in their buildings. By requiring short-term rental hosts to register with the Office of Special Enforcement (OSE) and confirm that they have a right to rent the space — and by imposing stiff fines on violators — the law has caused the number of illegal Airbnb listings to plunge by 15,000.    Read the article…………………………….