Standard methods of nonlinear dynamics are used to investigate the stability of particles, branes and D-branes of abelian Born–Infeld theory. In particular the equation of small fluctuations about the D–brane is derived and converted into a modified Mathieu equation and – complementing earlier low–energy investigations in the case of the dilaton–axion system – studied in the high–energy domain....

In the early 80-ties it became clear that the classification of the non-abelian finite simple groups was complete. Among the finite simple groups we find several families: the alternating groups and various families of groups of Lietype and their twisted analogues. Besides these families there exist 26 sporadic finite simple groups. Buildings are natural geometries for the groups of Lie-type (a...