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Newcastle MathsJam April 2012 Recap

April’s MathsJam was very enjoyable. We did a bit of arts and crafts, a bit of playing games, and if it had been NBA Jam instead of Maths Jam I would have been entirely on fire because I used up all my IQ points solving some very fun puzzles. Durham were still on their Easter holidays so the attendance was a modest six people. That was just enough for everyone to be doing the same thing at the same time, so we had a good time.

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Newcastle MathsJam March 2012 Recap

It’s been two months since I last wrote one of these! March was a haze of overwork and stress for me, so I didn’t write a recap for March’s MathsJam while it was still March. Peter Rowlett, who was visiting Newcastle as part of his mission to avoid having to think up new puzzles for MathsJams by always attending different ones (and also to give a talk at the university) has kindly sent me his notes, so here’s what I’ve reconstructed:

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Slides about the princess in a castle puzzle

I gave a talk to our internal postgrad forum last week about the princess in a castle puzzle. I made some slides for it using deck.js. They looked quite nice and I could just about get what I wanted in them, but I now know that using SVG in HTML is still an enormous faff if you want it to scale nicely, which is basically the only reason you would use SVG.

Click here to see the slides.

I’m not sure if you can follow along with the slides without me talking; maybe I’ll do a transcript with slide drive later.

Newcastle MathsJam February 2012 Recap

February’s MathsJam was loads of fun! We had a record attendance of 14 cheery people who just about managed to fit around the biggest table in the Charles Grey.

After last month’s puzzlocalypse, which left me for over a week unable to count the toes on my feet, I wanted to have a nice relaxed evening.

IMAG0270 - christianp - Flickr

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Newcastle MathsJam January 2012 Recap

January’s MathsJam was a bit massive. It’s now a week later and I’ve only just gathered enough thoughts together to do this writeup.

There were nine of us this month, all but one of whom either maths students or lecturers. A major theme of the night was of professional mathematicians or nearly-professional mathematicians forgetting basic high-school methods. This led to quite an intense session of puzzling and proving.

Things didn’t start out that way, though. A few weeks ago I found the website of a mathematician in Illinois called Alan Schoen, and his page about Lominoes. They’re a pretty interesting set of shapes! I ordered a couple of sets and they arrived just in time for the MathsJam.

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Newcastle MathsJam December 2011 Recap

Amazingly, December’s MathsJam had a non-trivial attendance of six whole people. And not just any people! Puzzling heavyweight David Cushing had yet more Renaissance-era riddles to test us all, and the other regulars were in similarly bamboozling form.

I balanced things out by failing to prepare anything or bringing anything to take notes on and subsequently forgetting most of what the others talked about. So this isn’t going to be a very accurate record of what happened, unless I get some reminders in the comments.

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Solving the “princess on a graph” puzzle

This post is about the best logic puzzle I’ve seen in absolutely ages. It’s easy to explain and doesn’t require any silly tricks, but has a decent amount of depth to it and challenges your intuition. I’m going to present the puzzle, an extended version of the puzzle, and a general solution to the extended version.

The “classic” puzzle was told to me by David Cushing, who was told it by Alistair Bird, who himself found it on the MathOverflow “math puzzles for dinner” thread.

The setup goes like this:

  • there is a castle with 17 rooms in it, arranged in a line.
  • the princess who lives in the castle sleeps in a different room each night, but always one adjacent to the one she slept in the previous night. She is free pick any room to sleep in on the first night.
  • a prince would like to find the princess, but she will not tell him where she is going to sleep each night.
  • the prince can look in a single room each night, with no other restrictions

And the puzzle is:

Is there a strategy the prince can follow to guarantee he looks in the room the princess is sleeping in within a finite number of days?

If you haven’t seen this puzzle before, look away from the screen now and spend some time working out the solution. Try starting with castles of just a few rooms, and see if you can spot a pattern in the winning strategies. This version of the puzzle is definitely solvable by just sitting and thinking for a while.

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