Alan Turing's Cryptic 'Josephus Problem' Postcard to be Auctioned

633c1204f0a1cd6f1e0567d439689785b9633252.pngA postcard sent by Alan Turing to a psychiatrist friend in Manchester will be auctioned by Boston-based RR Auction.

Addressed to Dr. Franz Greenbaum and his children, it was sent by Turing from his Club Mediterranee holiday on Corfu, in July 23, 1953.

Reads in full: "I hope you are all enjoying your selves as well as I am here at Corfu. It is tremendously hot and one wears bathing things all day."

The front of the rare color postcard depicts an illuminated manuscript from Flavius Josephus' Antiquities of the Jews.

The first-century Romano-Jewish scholar Flavius Josephus, who commanded the Jewish forces at the Siege of Yodfat, is the namesake of the ‘Josephus Problem’ in computer science. Josephus describes a ‘counting-out game’ by which he and his soldiers, facing inevitable defeat, agreed upon an unusual suicide pact rather than surrender.

Standing in a circle, the first soldier killed the man to his left. The next surviving soldier then killed the man to his left, and this pattern continued until Josephus was the lone survivor.

The problem is thus: faced with the same situation, how could you determine where to position yourself in order to be the last man standing?

“Turing, who was fascinated by these types of algorithmic puzzles, surely knew of the ‘Josephus Problem’ and it is likely the reason he chose this specific postcard,” said Robert Livingston, Executive VP at RR Auction.

Turing became a patient of the Jungian psychologist Dr. Franz Greenbaum in 1952, and became a friend of the family; in a letter from July 10th, he had written to the doctor's daughter, Maria Greenbaum, about solving a solitaire puzzle.  

In Sara Turing's pioneering 1959 biography of her son she noted that he 'normally shirked letter-writing,' and his autograph is indeed incredibly scarce in any form.

Among other items featured in the auction:

Thomas Edison signed document selling the rights to his very first successful invention—the electro-magnetic printing telegraph.

Striking 1934 Albert Einstein etching signed by subject and artist.

Robert Fulton original diagram drawing of a cross-section of a torpedo flintlock detonator in ink and watercolor. 

Albert Einstein letter where he laments his inability to help create “a special teaching post for atomic mechanics.”

The Fine Autographs And Artifacts from RR Auction began on January 20 and will conclude on February 8. More details can be found online at

Auction Guide