Group properties:
  1. Applying subsequently the symmetry operations B and A that belong to the group, gives a symmetry operation C that also belongs to the group. We call this "Multiplication"
  2. An identity element E exists, such that EA=A
  3. The elements of the group have the ossiciative property A(BC)=(AB)C
  4. To every element A corresponds an inverse  that also belongs to the group. Such that  * =

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