... a first trial to classify topological spaces. Topology frequentlyresorts to this kind of practice, trying to place the space in some hierarchy.In the study of the anatomy of a topological space, ... prototype basis, but one might think of opencubes, open tetrahedra, etc. It is useful, to get some insight, to think aboutopen disks, open triangles and open rectangles on the euclidean plane ... Vorticity, shear and expansion . . . . . . . . . . . . . . 48012.2.3 Landau–Raychaudhury equation . . . . . . . . . . . . . 483V PHYSICAL TOPICS 4851 HAMILTONIAN MECHANICS 4871.1 Introduction...