There seem to be a bumper list of mathematical advent calendars this year, even though the stellar efforts of Katie and Christian’s Aperiodvent Calendar 2015 aren’t being repeated. There aren’t yet enough for an advent calendar with a different mathematical advent calendar behind each door, so we thought a straight round up was the way to go.

# Maths Journals for an engaged Sixth Former

Maths legend Colin Wright posed this question on Twitter:

Q for my maths tweeps – recommendations wanted for Maths Journals suitable for a bright and engaged Sixth Form student. Suggestions?

— Colin Wright (@ColinTheMathmo) November 24, 2016

It led to a flurry of interesting replies, and here’s some of them.

# 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

# Education bits: new PBS maths series, National Numeracy game, etc.

I’m not normally interested in education stuff, but we’ve had a flurry of emails from various people telling us about their projects, and I’ve got nothing else to do today, so I thought I’d round them up.

# 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: Mini-podcast with Ben Sparks and James Grime

As part of our special Apéry takeover today, I chatted to mathematicians Ben Sparks and James Grime, to find out what we know about the mathematics Apéry did – it’s an enjoyable 10-minute listen.

Podcast: Play in new window | Download

# 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.