## About clip-on ties, real ties and mathematics

Rumor has it that today, 84 years ago in 1928, some clever folk came up with the concept of the clip-on tie. You know, those ties that look like the real deal, but instead of being tied around your neck just consist of the hanging bit with a permanent knot at the top, which can be attached to your shirt via a little metal clip stuck to the back of the knot.

I’m not sure if it was originally designed for people too lazy to tie a tie, or for people who had difficulty mastering the skill, but it proved to be quite a useful invention. Disabled people can use it without trouble. So can kids. Cops and security personnel wear clip-on ties as a safety precaution – it negates the potential risk of being strangled by your conventional necktie. Similarly, people in factory environments who wear ties are also advised to wear clip-ons – in the unfortunate event that the tie gets caught in a piece of machinery, it will simply clip off, rather than pulling its owner into the machine as well. (Then again, why people in factories would wear ties I have no idea.)

On the downside, clip-ons aren’t exactly haute couture – you are unlikely to get a designer-styled, silk clip-on tie. And a clip-on tie pretty much looks like a clip-on tie – the unique individuality of a slightly unsymmetrical knot is not an option. And of course you cannot go for the cool chic of the ‘loosened tie look’ with your clip-on tie – well, I guess you can clip it on to one side of your loosened collar, but somehow it just ain’t going to have the same effect!

So what does a clip-on tie have to do with science, you may ask? Well, very little, but it did bring to mind a mathematics book by Thomas Fink and Yong Mao, called ‘The 85 ways to tie a tie’ – a book where the authors use concepts from topology and a mathematical representation of knots to prove that a conventional neck tie can be tied in exactly 85 possible ways. The 85 ways are pretty theoretical – apparently only a dozen or so are sufficiently unique and handsome to be sensible candidates for an actual tie knot.

Yes, today is about ties, but as is often the case, the maths are lurking just below the surface!

## Take time out to visit a lighthouse on Lighthouse Day

Today is Lighthouse Day, created to commemorate the day in 1789 when US Congress approved an Act for the establishment and support of lighthouses, beacons, buoys and public piers.

While this is a US commemoration, it’s surely reason enough to celebrate the important role fulfilled by lighthouses the world over, marking treacherous coastlines, hazardous shoals, reefs and safe entries to harbors.

Many lighthouses have fallen into disuse due to high maintenance costs and the emergence of new electronic navigation systems. The aim of Lighthouse Day is to focus attention on these imposing landmarks from our past, and to create awareness about local, national and international societies and organisations making an effort to preserve lighthouses for future generations.

Lighthouses traditionally symbolise safety, stability and truth, and as such their preservation holds symbolic importance for mankind. Go on, pay a visit to your nearest lighthouse and take time to appreciate its grandeur. And don’t forget to take some photos – lighthouses are famously photogenic entities!