Logic-Puzzles.org is a great new site that is dedicated to logic grid puzzles.  These puzzles feature a set of assertions, generally about a group of people and what kind of pets they have, what color hats they wear, etc.  The goal is to determine from the limited set of assertions, which pet each person has, etc.  There is a grid that accompanies the puzzle that helps you solve it.

Logic-Puzzles.org provides a seemingly unlimited amount of these puzzles and a great interface for playing them.  The grid is provided for you and you can fill it out on the site.  The site will also keep time, so that you know how long it takes you to solve a puzzle.  I would highly recommend checking it out.

Passion for Puzzles recently had an article about Eintein’s Puzzle, sometimes known as the Zebra Puzzle (for reasons that will become clear shortly.)  The puzzle is generally said to have been written by Einstein as a boy, though there’s no evidence for this.  It’s also claimed that only 2 percent of the population can solve the puzzle.  Presumably there’s no evidence to back up that claim either.  The original puzzle can be found at the wikipedia page above.  It’s a standard logic puzzle.  We are given a series of assertions about a group of 5 men and their various unshared attributes and are asked at the end: “Who owns the zebra?”  (Hence the name Zebra Puzzle.)

Passion for Puzzles brings this up in reference to an open source puzzle game called Einstein’s Puzzle which can be found here.  The software doesn’t pose Einstein’s Puzzle exactly, but something very similar.  In the puzzle game we are presented with 6 rows to be filled in by 6 symbols of different type.  (i.e. One row will be filled by the Arabic numerals 1 to 6.  Another the letters A to F.  Another the Roman numerals I to VI. etc.)  We are also given a set of assertions as to where these symbols lie.  The charm of the original Einstein Puzzle is gone.  We are no longer asked to imagine five men of diverse nationalities living side by side in rainbow colored houses, smoking and drinking, and keeping exotic pets.  However, all of the puzzle difficulty is still there.  It’s also fun because there is a new puzzle every time you play.

The software is available for Windows and Mac.  The source is also available for those who wish to compile it for Unix-like systems.  And it’s released under the GPL.  It’s worth checking out.

Recently I came across this site through Digg, having the title “Very Difficult Analytical Puzzles.” I found a little more than that at the actual site. There’s a collection of logic puzzles ranging from “Very Easy” to “Very Difficult” and there was also a collection of lateral thinking problems.

We’re all familiar with lateral thinking problems which describe a mysterious situation and require a few key details from the solver in order to explain everything. When playing with friends, you get to ask yes or no questions from the person posing the problem. Most of the lateral thinking prooblems on this site were familiar to me, but what interested me most is the categories he came up with for lateral thinking problems.

• Preconceptions - Problems that challenge your preconceptions.
• Fact - Problems that arebased on fact.
• Fanciful - Problems that require a little imagination to solve.
• Semantics - Problems that require you to pay close attention to the wording of the problem.

As I think about it, these categories may be useful for classifying riddles in general.

It’s been a while since I did a post on a type of puzzle, so I thought I’d write about logic puzzles.  Of course, all puzzles require a bit of logic, but the puzzles that I’m referring to here take a particular form.  There’s a certain number of people (about 5) with a certain number of characteristics.  We are then given a series of statements followed by a question.  You know how this goes:

The clown with red hair is standing next to the one who smells like lemons.  The clown with the polka-dot tie is not wearing yellow shoes.  Which clown speaks German? (Not a real puzzle.  Don’t try to solve it.)

In my sidebar I’ve provided links to a couple of sites that provide these kinds of puzzles.  The Logic Zone has by far the best organized collection, with several puzzles classified as easy, medium, or hard.  Judy’s Logic Problems is also quite nice.  It’s got more of a feel of a personal homepage but there are some good puzzles there too.  Finally, I thought I’d link to Mystery Master, a piece of software that can solve all logic problems.  This link is included in case you get really frustrated.