The waiter informs them that the meal has been paid by someone, who could be one of the cryptographers or the National Security Agency (NSA).
Year 2000 problem | Waring's problem | The Final Problem | The Problem with Popplers | Hume and the Problem of Causation | Dirichlet problem | Boolean satisfiability problem | The Dog Problem | Tammes problem | Species problem | problem solving | Problem gambling | Packing problem | packing problem | dining car | chess problem | Znám's problem | Year 10,000 problem | Yamabe problem | Weber problem | Undecidable problem | Travelling salesman problem | travelling salesman problem | The Problem of Thor Bridge | The Problem of the Media: U.S. Communication Politics in the 21st Century | The Problem of Social Cost | The lower parts of the walls of the 16th century dining hall of St John's College, Cambridge | Tarski's circle squaring problem | Steiner tree problem | Shortest path problem |