We tested FCD also on the largest closed-class classification problem 252 (task I) from the 2012 PAN competition: open-class problems were not 253 considered as the simple classification algorithm adopted does not allow a 254 rejection class. Using a corpus of 14 test and 28 training texts belonging 255 to 14 different authors, the FCD (using a simple nearest neighbour classi- 256 fication criterion) assigns correctly 12 out of 14 documents to their correct 257 authors. Out of the 25 which took part to the competition, only 4 methods 258 submitted by three groups (Sapkota and Solorio, 2012; Tanguy et al., 2012; 259 Popescu and Grozea, 2012) outperformed our method (all of them with 13 260 documents correctly recognized). As a comparison, the NCD and trigrams- 261 based CNG (using the most meaningful 1000 trigrams per document, as this 262 setting yields the best results in Table 2) assigned 2 and 9 documents out 263 of 14 to the correct author, respectively. The results in Tables 4 and 5 are 264 encouraging, specially if we consider that the FCD is a general method which 265 is not specific for the described tasks. 266 18 Task FCD Best PAN Rank Overall 72.9 % 75.3 % 2 English 83 % 80 % 1 Greek 63 % 83 % 5 Spanish 72 % 84 % 5 Table 4: Author identification task of the CLEF PAN 2013 dataset. The dataset contains 349 training texts plus 85 test documents of questioned authorship, with problems given in English, Greek and Spanish. The table reports how the FCD ranks compared to 18 participants to the PAN 2013 contest. The first ranked submission for each problem is reported as ‘Best PAN’.