## Raspberry Pi, Squeezebox, phone line

Motivation Long ago, I built a circuit which enabled a PC to monitor the phone line, and control the music system in our old house. Whenever somebody rang, it would pause the music, and announce the caller using voice synthesis. It was cool. Details are on a pre-blog page. Alas, when we moved house, the hardware got lost, and ever since, we have had to manually pause the music, and look at the tiny display on the phone to see who was calling. I had been meaning to reinstate the automatic system for ages; it had actually been quite useful. Photo © Flickr user GijsbertPeijsCC-BY-2.0 The other motivation for this project was as an excuse to play with the Raspberry

## UK government consultation on Open Standards

Back in June, I submitted a response (also as pp.35–39 of a PDF on the Cabinet Office’s site) to the UK’s consultation on open standards in government. Today I received an email notifying me of the conclusions to this process. I have read through the UK government’s ‘Principles’ document, and the following snippets are quite encouraging: ‘Open’ includes ‘royalty-free’ I think the big one is the inclusion of ‘royalty-free’ in the requirements for a standard to be ‘Open’: 2. Open standard – definition … Rights – rights essential to implementation of the standard, and for interfacing with other implementations which have adopted that same standard, are licensed on a royalty free basis that is compatible with both open source and

## An unusual primality test

A few years ago, I came across The Computist Quiz, and one question in particular led to some interesting mathematics: Amphibious Discursion A predicate on positive integers: boolean isToad(int n) { return ( (n == 2) || (n == frog(4, floor((n – 1) / 2), 1, 0) – 1)); } is defined with the aid of the following helper method: int frog(int q, int r, int s, int t) { if (r < t) return 0; else if (r == t) return 1; else if (q == 0) return 0; else return (frog(q, r, s + 1, s + t) + frog(q – 1, r – t, 1, 0)); } Which integers are toads? Describe what the frog method does.

## MazezaM is NP complete

Update 20170129: My claim that Mazezam is NP-complete is not shown by this argument. The argument does show that Mazezam is NP-hard, but it is not clear that Mazezam is itself in NP. See a follow-up post for more details. Many thanks to Aaron Williams for contacting me to point out my error. The post about AutoFickle reminded me of something I did a good while ago (2008) which doesn’t currently have a home. The connection is that this is also a project based on a game written by Malcolm Tyrrell. The game this time is MazezaM, dated 2002–2004; in it you push rows of blocks back and forth, trying to get from the entrance to the exit of a

## AutoFickle

Fickle is a one-button Vic20 game written by my friend Malcolm Tyrrell. In it, you steer a character called Fickle through a maze, trying to reach a heart. I wrote AutoFickle, an automatic player for this game, which solves all fifteen levels straight through.

## Another stop-motion: Witch stirring potion

Did this with Meg last Christmas day, but only getting round now to putting the loops in and uploading. The AGC in the webcam was playing up a bit, so I tried to fix the exposures but some flashing and colour oddness remains.