Monthly Archives: March 2014

Most difficult chess problem

Neil Bickford has exhaustively searched the space of 5 × 4 sliding-block puzzles* to determine the one with the longest minimal solution. The unique result, which requires a whopping 235 moves, happens to be Bob Henderson’s Gauntlet puzzle: *subject to the … Continue reading

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Cipher 62: Also untitled

By the way, we’ve raised £463.00 so far for the Schistosomiasis Control Initiative (see this post for an explanation). This week’s cipher uses a couple of relatively simple ideas, although I could imagine it being difficult to cryptanalyse. DKGOQXIWSASPYKOWEEPLELTLELFSKTPITLJFCLXSANZRYYNTAAJDQC Good … Continue reading

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Denser packing of pound coins discovered

Until very recently, the densest known packing of pound coins in the plane was the hexagonal lattice packing of circles, which achieves a density of π/√12 ≈ 0.9069. This was proved by Axel Thue to be the densest arrangement of … Continue reading

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Cipher 61: Discrepancy

Slightly less major announcement: Stuart Gascoigne has now solved a total of 50 ciphers, earning the first ‘gold star’ icon on the solvers page. 00111101 11011100 11110011 00111110 00010110 11011110 00100000 11010111 10000001 00001000 11010111 10111111 11101101 00101110 11111010 00111110 00000010 10110001 … Continue reading

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Rectangular hyperbolae and the orthocentre

Firstly, a major announcement: Maria Holdcroft (whom you may remember from the cipher solvers page) and I will be performing a charity skydive on the 2nd April! If you wish to sponsor us, please specify the amount you intend to donate by commenting … Continue reading

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Cipher 60: Tuesday comes between Wednesday and Friday this week

The more astute observers amongst you may have noticed that this particular cipher is two days later than is usual, as a consequence of a particularly busy week. Hence, I had no choice but to officially postpone Tuesday by 48 … Continue reading

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One of the most miraculous phenomena in the universe is, unarguably, the existence of biological life. Whilst evolution nicely accounts for the gradual progression from the earliest archaeobacteria to the vast array of multicellular creatures capable of astounding feats of … Continue reading

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Cipher 59: Iterated question-answering

This is another particularly satisfying one to solve. XGJDGSZUIDSSDDDOURPMHDNOUZJMTBMVNAFQTVBISIBSUIDS HOHNGHOUDHFQTHOUGFOTNAFSEJDMEFFODSZUFCCZHUEPSLBM JOSFHQBKEPLBHOUGBUHTDVDKJEDBMCVSONUONSNDVBMJCFZO Good luck. As usual, the password is in lower-case and contains no punctuation. Also, it is precisely twelve letters in length.

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