Libtextcat is a library with functions that implement the classification
technique described in Cavnar & Trenkle, "N-Gram-Based Text Categorization" [1].
It was primarily developed for language guessing, a task on which it is known to
perform with near-perfect accuracy.

The central idea of the Cavnar & Trenkle technique is to calculate a
"fingerprint" of a document with an unknown category, and compare this with the
fingerprints of a number of documents of which the categories are known. The
categories of the closest matches are output as the classification. A
fingerprint is a list of the most frequent n-grams occurring in a document,
ordered by frequency. Fingerprints are compared with a simple out-of-place
metric.

[1] The document that started it all: William B. Cavnar & John M. Trenkle (1994)
N-Gram-Based Text Categorization, <http://citeseer.ist.psu.edu/68861.html>.

WWW: http://software.wise-guys.nl/libtextcat/