With the security problem of image information as the background, some more properties of the period of Arnold transformation of two-dimension were studied by means of introducing a integer sequence. Some new resuits are obtained. Two interesting conjectures on the period of Arnold transformation are given. When making digital images scrambling by Arnold transformation, it is important to know the period of the transformation for the image. As the application of the theory, a new method for computing the periods at last are proposed.
We consider the mixed arrangement which is com posed of the central hyperplane arrangement and a sphere. We discuss the lattice of its intersection set and the relationship between the Mbius function of the mixed arrangement and the original hyperplane arangement. The Mbius function of the mixed arrangement is equal to the positive or the negative Mbius function of original hyperplane arrangement. Moreover, we give an equality of the chambers and the characteristic polynomial for the mixed arrangement.
