before embarking into the jungle of papers comparing the animals of the classifier zoo, you might invest ten minutes reading the following :
http://arxiv.org/pdf/math/0606441.pdf
Hand D.J. (2006) Classifier technology and the illusion of progress. Statistical Science, 21, 1-34.
although i would not fully agree with the very abrupt conclusion of the author, i think this provocative paper is a useful reminder of all that is left outside of most if not all those" zoological" studies
You can check the papers on topic identification applied to Arabic texts:
M. Abbas, K. Smaili, D. Berkani. (2010). TR-Classifier and kNN Evaluation for Topic Identification Tasks. Special Issue on Advances in Arabic Language Processing, the International Journal on Information and Communication Technologies (IJICT), Vol 3, N 3, pp. 65-74, Serial Publications.
M. Abbas, K. Smaili, D. Berkani. (2011). Evaluation of Topic Identification Methods on Arabic Corpora. Journal of Digital Information Management Vol. 9 No. 5, pp.185-192.
M. Abbas, K. Smaili, D. Berkani, "Evaluation of Topic Identification Methods for Arabic Texts and their Combination by using a Corpus Extracted from the Omani Newspaper Alwatan." Arab Gulf Journal of Scientific Research 29.3-4 (2011): 183-191.