TURKISH JOURNAL OF MATHEMATICS, cilt.34, sa.4, ss.585-592, 2010 (SCI-Expanded)
We compute the growth series and the growth functions of reducible and pseudo-Anosov elements of the pure mapping class group of the sphere with four holes with respect to a certain generating set We prove that the ratio of the number of pseudo-Anosov elements to that of all elements in a ball with center at the identity tends to one as the radius of the ball tends to infinity