The famous photograph was taken in 1951 during the physicist’s 72nd birthday celebration. Einstein signed it and gave it to CBS correspondent Howard Smith, whose programmes he enjoyed. The inscription read: “You will like this gesture because it is directed at all humanity.” The photograph immediately became popular, appearing on everything from T-shirts to car advertisements. Einstein himself is said to have loved it
The famous photograph was taken in 1951 during the physicist’s 72nd birthday celebration. Einstein signed it and gave it to CBS correspondent Howard Smith, whose programmes he enjoyed. The inscription read: “You will like this gesture because it is directed at all humanity.” The photograph immediately became popular, appearing on everything from T-shirts to car advertisements. Einstein himself is said to have loved it · Source

Many books, websites and forums feature a logic problem allegedly devised by Albert Einstein himself. It is known as Einstein’s Puzzle or Einstein’s Riddle, or as the Zebra Puzzle.

Here are claims about it that have no documentary support, since Einstein himself never made such statements:

  • Einstein invented the problem as a child;
  • Lewis Carroll was the puzzle’s author;
  • Einstein used it to test prospective assistants’ logical thinking;
  • Einstein said that only 2% of the world’s population could solve it;
  • the puzzle can be solved mentally, without paper or notes.

The original problem

Here is the first known published version, which appeared in the 17 December 1962 issue of Life International Magazine.

A page from Life International Magazine dated 17.12.1962 with the Einstein riddle reproduced in this article
A page from Life International Magazine dated 17.12.1962 with the Einstein riddle reproduced in this article · Source
  1. There are five houses on a street.
  2. The Englishman lives in the red house.
  3. The Spaniard owns a dog.
  4. Coffee is drunk in the green house.
  5. The Ukrainian drinks tea.
  6. The green house is immediately to the right of the white house.
  7. The Old Gold smoker keeps snails.
  8. Kool is smoked in the yellow house.
  9. Milk is drunk in the middle house.
  10. The Norwegian lives in the first house.
  11. The Chesterfield smoker’s neighbour keeps a fox.
  12. Kool is smoked in the house next to the one where the horse is kept.
  13. The Lucky Strike smoker drinks orange juice.
  14. The Japanese man smokes Parliament.
  15. The Norwegian lives next to the blue house.

Who drinks water? Who owns the zebra?

For clarity, each of the five houses has a different colour, and their residents, of different nationalities, own different animals, drink different beverages and smoke different brands of American cigarettes. One further note: in statement 6, “right” means to your right.

We invite you to solve this logic problem too. (Find the answer and one possible solution in the comments on the Mathematics with Mansur-abyy Telegram channel.)

Hint. A table is the most convenient method. Try entering the known information and successively eliminating impossible combinations.

The original statement omits some details, particularly that the houses stand in a row. Their numbering may run from either left or right, but it is consecutive.

Since the statement does not say that anyone drinks water or owns a zebra, these are assumed as implicit premises. Otherwise, the answer would be “Insufficient information”.

In this version, the problem is set for mental solution, without notes or any means of storing information. Without these restrictions, it becomes considerably less difficult.

Nevertheless, any solution is valid. It will give you the pleasure of untangling a situation involving five characteristics at once.