## 30 July 2007

### Danica McKellar's "Math Doesn't Suck", and Erdos-Bacon numbers

The book itself appears to be a mixture of mathematics tips and motivational prose; I will refrain from commenting on the book, because I haven't read it. There are fully-worked-out solutions to the problems in the book, which might help you figure out what mathematics it covers; it appears to include the highlights of a pretty standard middle-school mathematics curriculum in a U. S. school. McKellar has focused some of her philanthropic efforts on the importance of quality education, including the Figure this! campaign; her web page also includes a section where she offers math help to people who write in with questions. (Will we ever see a mathematician who offers acting tips on their web page?)

McKellar is one of the eighteen or so people with a finite Erdos-Bacon number. A person's Erdos number is defined to be zero if they are Paul Erdos; otherwise it is the minimum of the Erdos numbers of the people with whom they have cowritten scholarly papers, plus one. More informally, it is the length of the shortest chain of collaboration that connected a person to Erdos. If a person can not be connected to Erdos by such a chain, their Erdos number is said to be infinite. Bacon numbers are defined similarly, but Erdos is replaced by Kevin Bacon and "have cowritten a scholarly paper" is replaced by "have appeared in the same movie". A person's Erdos-Bacon number is the sum of their Erdos number and their Bacon number; thus to have a finite such number a person needs to have appeared in a movie and written an academic paper. The canonical source on Erdos numbers is Jerry Grossman's Erdos number project; I'm not aware of a single canonical source for Bacon numbers.

Another person with an Erdos-Bacon number who's been in the news a lot lately is, believe it or not, Hank Aaron, he of the 755 home runs -- although this one is a bit facetious; Hank Aaron and Paul Erdos both autographed the same baseball, giving him an Erdos number of 1; Hank Aaron also appeared in the baseball movie Summer Catch as himself, thus connecting him to the acting world. It turns out his Bacon number is 2, giving him an Erdos-Bacon number of 3. (Some people claim that appearances as oneself don't count towards Bacon numbers.)

If you don't count people who appeared as extras or as themselves -- but only people who are credited as appearing as someone other than themselves -- the lowest Erdos-Bacon number is either 4 or 5, and it belongs to Dave Bayer, a mathematician who played a small role in A Beautiful Mind.

p. squiddy said...

The Oracle of Bacon at UVA is, I believe, the authoritative source for Bacon numbers: http://oracleofbacon.org/

Brian said...

Isabel,
Awesome site. I am also awaiting the publication of "Math Doesn't Suck." It sounds like such and important undertaking.

I used to be a mathophobe, but I saw the light in my thirties. I wish there had been cool blogs like yours where I could have gone to find out how great is when I was young.

Keep up the good work!

Brian (a.k.a. Professor Homunculus at Mathmojo.com)