Rubik’s Cube solved in 25 moves

rubik’s cubeMy wife and I are Rubik’s Cube enthusiasts. While I can solve it in about 5 minutes, my wife can solve it faster one layer at a time. There are many who can solve it in under a minute!

Rubik’s Cube is supposed to be the world’s best-selling toy and over 300 million Rubik’s Cubes and variants (2x2x2, 4x4x4, 5x5x5) have been sold worldwide.

The fastest is Edouard Chambon who has an average solve time of 11.48 seconds and a record of 9.18 seconds!

My personal favourite Rubik’s Cube solver is Jessica Fridrich, a speedcuber whose moves are the most commonly used for speedcubers.

Today, Slashdot linked to an article about how Rubik’s Cube can be solved in just 25 moves!

Stanford mathematician Tomas Rokicki has lowered last year’s record of 26 moves to 25.

According to the article,

Rokicki’s proof is a neat piece of computer science. He’s used the symmetry of the cube to study transformations of the cube in sets, rather than as individual moves. This allows him to separate the “cube space” into 2 billion sets each containing 20 billion elements. He then shows that a large number of these sets are essentially equivalent to other sets and so can be ignored.

If you’re a Rubik’s Cube enthusiast interested in decreasing your solve times, go ahead and read the full article.


Retard Award: Professor who says fractions should be scrapped

The latest retard award goes to this award winning Mathematics professor who says that fractions should NOT be taught in schools. He is releasing a book about it. He favours decimals over fractions, wants to eliminate manual long division, calculation of square roots and multiplication of long numbers (yes, without using calculators).

According to this excerpt:

PHILADELPHIA — A few years ago, Dennis DeTurck, an award-winning professor of mathematics at the University of Pennsylvania, stood at an outdoor podium on campus and proclaimed, “Down with fractions!”
“Fractions have had their day, being useful for by-hand calculation,” DeTurck said as part of a 60-second lecture series. “But in this digital age, they’re as obsolete as Roman numerals are.”

Wonderful! Thats exactly what today’s American kids need, right? Apart from whatever they are already getting on a golden platter at the moment. Kids in America need a calculator for everything. Even adults whip out a calculator all the time, for simple calculations. The kind lady at Kay’s had to pull out a calculator to find what 13 + 13 equalled.

Fractions are the most accurate representation of floating point numbers. I’m glad the other Math professors have actually objected to his statements.

Questioning the wisdom of teaching fractions to young students doesn’t compute with people such as George Andrews, a professor of mathematics at Pennsylvania State University and president-elect of the American Mathematical Society. “All of this is absurd,” Andrews said. “No wonder mathematical achievements in the country are so abysmal.

“Arithmetic is the basic skill. If children do not know arithmetic, they can’t go on to algebra, which leads to calculus. From there you go on to other things,” Andrews said. “It’s fine to talk about it, but this is not a good pedagogy.”

Others see value in both fractions and decimals. To Janine Remillard, associate professor of education at Penn, the decimal system is “incredibly powerful.” And fractions can be a powerful steppingstone to understanding decimals, she says.

“Fractions, if taught well — and that’s a huge caveat — can actually help kids understand the value of the size of the pieces,” Remillard says.

When his book is released later this year, the schools that would probably follow his ideas would be the academically low performing ones! It would be a big blow to the already pathetic state of Mathematics in the US if his book is used on a large scale country-wide.

I hope Dr. Dennis DeTurck is happy with his Retard Award. The prize carries a one-way ticket and permanent citizenship to Retard-Land where he can spend the rest of his life with people with equal IQ levels.

This joke will help you understand how Mathematics has changed over the years!

Read more here.