# Mathematical Digest

### Short Summaries of Articles about Mathematics

in the Popular Press

"Connect, Only Connect: it's Cool Now to Measure Degrees of Separation in Almost Anything," by Emily Eakin. New York Times, 25 January 2003, pages A10-A20.

"Follow your nodes": Review of *Six Degrees,* by Duncan Watts. Reviewed by David Cohen. *New Scientist,* 25 January 2003, page 54.

These two articles concern a book about the development of the science behind the popular phenomenon of "six degrees of separation": The notion that any two randomly chosen people will be linked by an average of six acquaintances. The author of the book, Duncan Watts, is one of the leading figures in this area of research, known as network theory. One of the surprising ideas to emerge from network theory is that networks generally are not connected randomly; rather, networks tend to consist of a small number of "hubs", which are connected to lots of other nodes, and many nodes that are connected to only a few other nodes. This fundamental insight may apply to a wide range of problems, from designing power grids to preventing epidemics.

*--- Allyn Jackson*