On the Number of Hamiltonian Groups

Finite hamiltonian groups are counted. The sequence of numbers of all groups of order $n$ all whose subgroups are normal and the sequence of numbers of all groups of order less or equal to $n$ all whose subgroups are normal are presented.Comment: 6 pages, 8 table

Hamilton cycles in graph bundles over a cycle with tree as a fibre

AbstractA sufficient and necessary condition for the existence of a Hamilton cycle in a graph bundle with a cycle as a base and a tree as a fibre is obtained

Symmetries of Hexagonal Molecular Graphs on the Torus

Symmetric properties of some molecular graphs on the torus are studied. In particular we determine which cubic cyclic Haar graphs are 1-regular, which is equivalent to saying that their line graphs are ½-arc-transitive. Although these symmetries make all vertices and all edges indistinguishable, they imply intrinsic chirality of the corresponding molecular graph