Line Graphs and Middle Graphs that are Divisor Graphs

In this paper it is determined when the line graphs and the middle graphs of some classes of graphs are divisor graphs. Complete characterizations for cycles, trees, complete graphs and complete multipartite graphs whose line graphs (middle graphs) are divisor graphs are obtained. It is also shown that the line graphs and the middle graphs of the cycle permutation graphs are never divisor graphs.

Nonlinearity of k-cycle permutations on ℤn

In this paper, we explore the existence and nonlinearity of affine [Formula: see text]-cycle permutations on [Formula: see text] for different values of [Formula: see text] and [Formula: see text]. It is proved that a transposition [Formula: see text] on [Formula: see text] has nonlinearity [Formula: see text] for [Formula: see text], a [Formula: see text]-cycle permutation on [Formula: see text] has nonlinearity [Formula: see text] for [Formula: see text], [Formula: see text] a prime. The number of affine [Formula: see text]-cycle permutations on [Formula: see text] and a bound for their nonlinearity have been obtained. Some results on the cyclic decomposition of a permutation on [Formula: see text], [Formula: see text] a prime, have also been proved.