Christian Lawson-Perfect

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Integer Sequence Reviews: A075771, A032799, A002717

By Christian Lawson-Perfect and David Cushing. Posted August 6, 2016

It’s been almost two years since I last sat down with my friend David Cushing and did what God put us on this Earth to do: review integer sequences.

This week I lured David into my office with promises of tasty food and showed him some sequences I’d found. Thanks to (and also in spite of) my Windows 10 laptop, the whole thing was recorded for your enjoyment. Here it is:

I can only apologise for the terrible quality of the video – I was only planning on using it as a reminder when I did a write-up, but once we’d finished I decided to just upload it to YouTube and be done with it.

Particularly mathematical Birthday Honours 2016

By Peter Rowlett and Christian Lawson-Perfect. Posted June 11, 2016

With the announcement the Queen’s Birthday Honours list, it’s time for the latest in our ongoing Honours-watch series of posts. In this, we search arbitrarily for ‘mathematics’ in the PDFs of the various lists, and hope our well-informed readers fill in the blanks where actual knowledge is required.

Prof. Alice Rogers, Emeritus Professor of Mathematics, King’s College, London, appointed OBE for services to Mathematics Education and Higher Education.
John Sidwell, volunteer, HMP Hewell appointed MBE for services to Prisoners through One to One Maths.
Danielle George, vice-dean for teaching and learning, Faculty of Engineering and Physical Sciences, University of Manchester, appointed MBE for services to engineering through public engagement.
Anthony Finkelstein, professor of software systems engineering, University College London and the Alan Turing Institute, for services to computer science and engineering.
Economist Angus Deaton, professor, Princeton University, Nobel laureate, for services to research in economics and international affairs.
Prof. Alan Thorpe, lately Director-General of the European Centre for Medium Range Weather Forecasts, appointed OBE for services to environmental science and research (thanks to Philip Browne on Twitter).
Prof. Nalini Joshi was made an Officer of the Order of Australia (AO); the citation is more involved than the UK ones and reads “for distinguished service to mathematical science and tertiary education as an academic, author and researcher, to professional societies, and as a role model and mentor of young mathematicians” (added in an update 16/06/16).

It’s also worth mentioning the new batch of Regius professorships, 12 posts created at universities around the UK to celebrate the Queen’s 90th birthday: Oxford University has been given a professorship in maths, but no appointment has been made yet.

Are there any others we’ve missed? Please add any of interest in the comments below. A full list may be obtained from the Cabinet Office website.

Armadillo Vault held together only by friction

By Christian Lawson-Perfect. Posted June 9, 2016

More information at Wired.

via math-fun.

CLP reads “Non-sexist solution to the ménage problem”

By Christian Lawson-Perfect. Posted May 27, 2016

I rediscovered this nice paper by Kenneth P. Bogart in my Interesting Esoterica collection, and decided to read through it. It turned out that, while the solution presented is very neat, there’s quite a bit of hard work to do to along the way. I’m not particularly experienced with combinatorics, so the little facts that the paper skips over took me quite a while to verify.

Once I was happy with the proof, I decided to record a video explaining how it works. Here it is:

I probably made mistakes. If you spot one, please write a polite correction in the comments.

There was a “beauty of maths” garden at the Chelsea Flower Show. Yeah, sure, why not

By Christian Lawson-Perfect. Posted May 27, 2016

The Winton Beauty of Mathematics Garden was an entry in this year’s Chelsea Flower Show. It looks like this:

Photo from Winton Capital, via The RHS on Twitter.

Apparently those symbols winding their way around the garden are “plant growth algorithms”, whatever those are.

There’s also a golden-ratio-thingy water feature, of course.

You can thank Winton Capital, sponsors of all sorts of worthy maths projects, for this bit of mathsy art.

This video about the proof of the Kelmans-Seymour conjecture is adorable

By Christian Lawson-Perfect. Posted May 26, 2016

Theorem: every 5-connected non-planar graph contains a subdivision of $K_5$.

The above statement, conjectured independently by Alexander Kelmans and Paul Seymour in the 70s, is very easy to say. And the video below, starring Dawei He, Yan Wang, and Xingxing Yu, makes it look very easy to prove:

It’s like they got Wes Anderson to film an academic PR video. In the normally uninspiring world of maths press releases, it’s quite refreshing. And the written press release is pretty snappy, too. Let’s not make this a thing, though.