Figure 2
Composition table of the groupoid Γ(0+1) representing an assembly of crystals constituted by a crystal and its four twinned variants , , and . The operators Σ1 and Σ3 are given with reference to the crystal . The composition of the operators appears as a multivalued function, for example Σ3Σ3 = {Σ1, Σ9}. |