“…The recent reviews (Davies et al, 2008;Vinga and Almeida, 2003) on published methods of alignment-free sequence comparison report several concepts of distance measures, such as Markov chain models and Kullback-Leibler discrepancy (Wu et al, 2001), chaos theory (Almeida et al, 2001), Kolmogorov complexity , decision tree induction algorithm (Huang et al, 2004), graphical representation (Liao and Wang, 2004;Randic et al, 2003;Yau et al, 2003), probabilistic measure (Pham and Zuegg, 2004;Yu et al, 2011). Furthermore, sequence vector representation approaches without alignment are also prevalent, such as composition vector (Chan et al, 2010;Chu et al, 2004;Gao and Qi, 2007;Qi et al, 2004), feature vector (Carr et al, 2010;Liu et al, 2006), and moment vector Yu et al, 2010).…”