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Posts Tagged ‘logic puzzles

Who owns the fish?…

From the good folks at Coudal Partners, a puzzle purportedly created by Albert Einstein…

There are five houses in a row in different colors. In each house lives a person with a different nationality. The five owners drink a different drink, smoke a different brand of cigar and keep a different pet, one of which is a Walleye Pike.

The question is– who owns the fish?

1. The Brit lives in the red house.
2. The Swede keeps dogs as pets.
3. The Dane drinks tea.
4. The green house is on the left of the white house.
5. The green house owner drinks coffee.
6. The person who smokes Pall Malls keeps birds.
7. The owner of the yellow house smokes Dunhills.
8. The man living in the house right in the center drinks milk.
9. The man who smokes Blends lives next to the one who keeps cats.
10. The Norwegian lives in the first house.
11. The man who keeps horses lives next to the one who smokes Dunhills.
12. The owner who smokes Bluemasters drinks beer.
13. The German smokes Princes.
14. The Norwegian lives next to the blue house.
15. The man who smokes Blends has a neighbor who drinks water.

There’s nothing up anyone’s sleeve (as though fish had sleeves…); and everything one needs to know is there.

Successful solutions can be confirmed here.  And readers can find a second fish puzzle here, and a little teaser called “Da Vinci’s Other Code” here.

As we scratch our heads, we might wish a Joyeux Anniversaire to silk weaver Joseph Marie Jacquard; he was born on this date in 1752.  Jacquard’s 1805 invention of the programmable power loom, controlled by a series of punched “instruction” cards and capable of weaving essentially any pattern, ignited a technological revolution in the textile industry… indeed, it set off a chain of revolutions: it inspired Charles Babbage in the design of his “Difference Engine” (the ur-computer), and later, Herman Hollerith, who used punched cards in the “tabulator” that he created for the 1890 Census… and in so doing, pioneered the use of those cards for computer input.

Joesph Marie Jacquard (source)


Suppose there is a town with just one male barber; and that every man in the town keeps himself clean-shaven: some by shaving themselves, some by attending the barber. It seems reasonable to imagine that the barber obeys the following rule: He shaves all and only those men in town who do not shave themselves. Under this scenario, we can ask the following question: Does the barber shave himself?

From Epimenides’ Paradox to the Omnipotence Paradox, more fun-with-logic at “Brain Twisting Paradoxes.”

As we return to first principles, we might wish a carefully-reasoned Joyeux Anniversaire to Félix-Édouard-Justin-Émile Borel, a mathematician and pioneer of measure theory and its application to probability theory; he was born in Saint-Affrique on this date in 1871.  Borel is perhaps best remembered by (if not for) his thought experiment demonstrating that a monkey hitting keys at random on a typewriter keyboard will– with absolute certainty– eventually type every book in the Bibliothèque Nationale (or, as oft repeated, every play in the works of Shakespeare, or…)– that is, the infinite monkey theorem.

Borel (image source)


Adventures in the Counterintuitive…

Your correspondent is headed away for a week or so, ranging more then ten times zones from home– the current limit to continuous timely posting of (R)D…  So, while regular service will resume on-or-around the 20th, a little something to keep one occupied:


Readers will recall that, on the occasion of an earlier hiatus, your correspondent wheeled out “the Monty Hall Problem” (c.f., “Riddle Me This” and “Birdbrains“).  This time, with thanks to Prof. Stan Wagon at Macalester College:

Monty Hall Takes a Vacation

Alice and Bob face three doors marked 1, 2, 3. Behind the doors are placed, randomly, a car, a key, and a goat. The couple wins the car if Bob finds the car and Alice finds the key.

First Bob (with Alice removed from the scene) will open a door; if the car is not behind it he can open a second door. If he fails to find the car, they lose. If he does find the car, then all doors are closed and Alice gets to open a door in the hope of finding the key and, if not, trying again with a second door.

Alice and Bob do not communicate except to make a plan beforehand. What is their best strategy?

Source: A. S. Landsberg (Physics, Claremont Colleges, California), Letters, Spring 2009 issue of The Mathematical Intelligencer.

The answer is here— and more nifty puzzles, here.

As we craft our own strategies, we might solve a memorial problem for Gabrielle-Émilie Le Tonnelier de Breteuil, Marquise du Châtelet, the French mathematician and physicist who is probably better known as Voltaire’s mistress; she died on this date in 1749.  Fascinated by the work of Newton and Leibniz, she dressed as a man to frequent the cafes where the scientific discussions of the time were held. Her major work was a translation of Newton’s Principia, for which Voltaire wrote the preface. The work was published a decade after her death, and was for many years the only translation of the Principia into French.

Judge me for my own merits, or lack of them, but do not look upon me as a mere appendage to this great general or that great scholar, this star that shines at the court of France or that famed author. I am in my own right a whole person, responsible to myself alone for all that I am, all that I say, all that I do. it may be that there are metaphysicians and philosophers whose learning is greater than mine, although I have not met them. Yet, they are but frail humans, too, and have their faults; so, when I add the sum total of my graces, I confess I am inferior to no one.
– Mme du Châtelet to Frederick the Great of Prussia


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