To arm or to disarm? This is the question in **Phil Wilson's** article, which explores the maths behind a cold war in slug world.

Everyone knows what symmetry is, and the ability to spot it seems to be hard-wired into our brains. **Mario Livio** explains how not only shapes, but also laws of nature can be symmetrical, and how this aids our understanding of the universe.

Get on a commuter train these days and you can virtually see people's brains crunching away at filling the numbers from 1 to 9 into a square grid. As the Sudoku craze shows no sign of slowing, **Hardeep Aiden** investigates its relatives and predecessors.

6174 is a very mysterious number. **Yutaka Nishiyama** explains why, and how beautiful mathematical oddities can inspire us to discover new mathematics.

Teaching a machine to understand music is an incredibly difficult task, which uses all the mathematical power of digital signal processing. But teaching a machine to compose music is quite another matter, and the wonderful world of mathematical patterns proves to be a gold mine. **Nick Collins** talks to *Plus* about his artificial musician.