The hypothesis is "anything sent through the mail will be stolen unless it is sent via padlocked box". Therefore, the padlocked box will be stolen unless it is sent in a larger padlocked box. And so on. This problem could serve to segue into the ordinal numbers. -- Gene From: Joerg Arndt <arndt@jjj.de> To: math-fun <math-fun@mailman.xmission.com> Sent: Tuesday, May 10, 2016 9:17 AM Subject: Re: [math-fun] Russian Postal Problem * Dan Asimov <asimov@msri.org> [May 10. 2016 16:19]:
This problem, and hundreds of other good ones, are in Peter Winkler's two books of fun problems for mathematicians.
Peter Winkler: {Mathematical Puzzles: A Connoisseur's Collection}, A K Peters, (2003). http://www.maa.org/publications/maa-reviews/mathematical-puzzlesa-connoisseu... Peter Winkler: {Mathematical Mind-Benders}, A K Peters, (2007). http://www.maa.org/publications/maa-reviews/mathematical-mind-benders In the latter we find our problem on page 9: "Love in Kleptopia Jan and Maria have fallen in love (via the internet) and Jan wishes to mail her a ring. Unfortunately, they live in the country of Kleptopia where anything sent through the mail will be stolen unless it is sent via padlocked box. Jan and Maria each have plenty of padlocks, but none to which the other has a key. How can Jan get the ring safely into Maria's hands?" Yes, lots of lovely problems there. Best regards, jj