## 21 November 2008

### Classification is hard, and libraries are not perfect

When I go to the library, even if it's just to get a specific book, I tend to browse a bit. I've found some interesting books this way.

So I was just there, and Anatomy of Integers, the proceedings of this conference, was shelved near the calculus textbooks. In particular, it was near various books that collect integrals. "Anatomy of integers" is a name that seems to be used for a certain branch of number theory that looks at the distribution of prime factors; for a nice introduction to the concept, see Andrew Granville's anatomy of integers and permutations. (This paper, still in development, talks about the analogy between the prime factorizations of integers and cycle structure of permutations. For example, the distribution of the number of cycles of a random permutation of {1, 2, ..., n} is approximately normal with mean and variance near log n; the Erdos-Kac theorem says that the distribution of the number of prime factors of a random integer less than or equal to en is asymptotically normal with mean and variance near log n. Lots of results about prime factorizations or about permutations seem to have counterparts in the other realm. Anyway, this isn't calculus! But it was with the calculus books.

Similarly, I found a book entitled Mathematical Essays: In Honor of Su Buchin, which was a volume of mathematical research articles in honor of the Chinese differential geometer Su Buchin, shelved with various books that consist of reflections by mathematicians on mathematics -- the sort of nontechnical writing that "essay" usually means.

Is there something wrong with Penn's library? Not at all. They were in the right place according to the Library of Congress Classification, but whoever does that classification seems to make the occasional error. Of course the reasons for these particular errors were obvious from the titles, which is why I spotted them. I am not sure if the classification is done by people who aren't familiar with mathematics; that would explain the integer/integral mistake, at least.

#### 1 comment:

Joseph said...

I've seen books on graphing data stored near books on graph theory.