Rubik’s cube manufacturer loses trademark battle

After all the excitement of the UK Rubik’s cube championships last weekend, the European Court of Justice ruled on Thursday that after 10-year legal battle, the trademark on the shape of the Rubik’s cube is not valid.

The trademark was registered in 1999, but since the original design of the cube was never patented, it’s long been on shaky ground. The court has ruled that the shape of the cube alone is not enough to protect it from copying, and that a patent would be needed to do so. The implications are that licensed manufacturers of the game could now face more competition from cheaper overseas sellers.

More information

Rubik’s Cube puzzled after losing EU trademark battle, at The Guardian
Rubik’s Cube shape not a trademark, rules top EU court, at BBC News

A more equitable statement of the jealous husbands puzzle

Every time I use the jealous husbands river crossing problem, I prefix it with a waffly apology about its formulation. You’ll see what I mean; here’s a standard statement of the puzzle:

Three married couples want to cross a river in a boat that is capable of holding only two people at a time, with the constraint that no woman can be in the presence of another man unless her (jealous) husband is also present. How should they cross the river with the least amount of rowing?

I’m planning to use this again next week. It’s a nice puzzle, good for exercises in problem-solving, particularly for Pólya’s “introduce suitable notation”. I wondered if there could be a better way to formulate the puzzle – one that isn’t so poorly stated in terms of gender equality and sexuality.

Apéryodical: Scratch and sniff ζ plot


Christian’s put together this fun applet for exploring the Zeta function – you can move your pointer around to reveal the value of $\zeta$ at each point in the complex plane.

The hue (colour) revealed is the argument of the value, and the lightness (bright to dark) represents the magnitude. There’s a blog post over at Gandhi Viswanathan’s Blog explaining how it works.

The resulting plot has contour lines showing how the function behaves.


Apéryodical: Roger Apéry’s Mathematical Story

This is a guest post by mathematician and maths communicator Ben Sparks.

Roger Apéry: 14th November 1916 – 18th December 1994

100 years ago (on 14th November) was born a Frenchman called Roger Apéry. He died in 1994, is buried in Paris, and upon his tombstone is the cryptic inscription:

\[ 1 + \frac{1}{8} + \frac{1}{27} +\frac{1}{64} + \cdots \neq \frac{p}{q} \]

Apéry's gravestone - Image from St. Andrews MacTutor Archive

Apéry’s gravestone – Image from St. Andrews MacTutor Archive

Roger Apéry - Image from St. Andrews MacTutor Archive

Roger Apéry – Image from St. Andrews MacTutor Archive

The centenary of Roger Apéry’s birth is an appropriate time to unpack something of this mathematical story.