美观，形式和功能：对称性探索

Plane Groups that describe symmetry operations in 2 dimensions are illustrated using the art of Escher. The 2D Bravais Lattices that capture all tiling permutations are covered together with the difference between ‘primitive’ and ‘centred’ unit cells.

The 17 Plane Groups are formally introduced and their representation in the International Tables of Crystallography explained. By mastering the plane group diagrams and figures, all common tessellations can be deconstructed into their symmetric components.

These lectures examine the role of symmetry in Islamic architecture and history in the context of regular and irregular networks. The transition to 3D or Space Symmetry is via the five Platonic Solids. The 2D symmetry operators (rotation, reflection, glide) are expanded to include screw axes and axial glide in 3D symmetry.

The 3D Bravais Lattices are the basis for describing the atomic relationships found in many crystalline materials. The way in which Space Symmetry determines not only the atomic locations but also the chemical composition of crystals is explained.