Can’t believe half term is nearly over – hope those of you who got a break enjoyed it and are ready to go again with Challenge 4 on Thursday. It is not over yet though, and here at Cipher Challenge central the Elves are enjoying a restful Sunday listening to podcasts and reading blogs! (They are particularly partial to The Archers Omnibus and have thoroughly earned a break – Christmas is coming and they will be on double duty with Santa and Harry over the next few weeks, so be kind to them!)
Harry’s in-tray this morning contained an interesting article from The Newsletter of (Not Quite) Everything, which does what it says on the tin. This one covered the internet trope “there is no such thing as purple” in a lazy, Saturday morning kind of a way that you might enjoy. I don’t mean the author is lazy, clearly very much the opposite, but it is brilliantly written and a very easy read if you, like Harry, are feeling lazy this morning!)
Harry particularly liked this article as he is currently visiting the Isaac Newton Institute in Cambridge and, of course, Newton was fascinated by light and colour. We think you might like John Elledge’s take on things.
If you are feeling in the mood for something a little more technical try this article in Quanta about the chromatic number of the plane. Think of it as a replacement for the puzzle this week – it is an open problem and as the article shows, amateurs have a chance of making a contribution to it. Unlike our other Sunday puzzles, fame and fortune (or at least, fame) will follow if you can solve it!
Enjoy!
PS, we are NOT endorsing or suggesting you subscribe to the substack, this post is a freebie from the author.
Also, the solution to last week’s puzzle is given below:
Remember that Alice, Bob and Claire want to play table tennis. Since there is only one table and two bats, they decide that whoever loses a game steps out for the next game to let the other person in. The players of the first game are chosen randomly. By the end of their session, Alice has played 17 games, Bob 15 and Claire 10. Who lost the second game?
To solve this we first note that the number of games played is (17+15+10)/2 = 21 and that no-one can sit out two games in a row. Grouping the games as {first, second}, {third, fourth} …{19th, 20th}, {21st}
we see that no-one can miss more than 11 games, and they can only sit out 11 if they miss exactly one game in each pair together with the final game. Since Claire won 10 of the 21 games she must have played and lost the penultimate game, which means she sat out the 19th game. She must therefore have lost the 18th and so on. working backwards we see that Claire lost the second game.