The axial symmetries are easier to find, since they impose fewer conditions of similarity between parts of the form. In fact, there is a tendency to consider this symmetry as a must for every RIGE, at least in the EE, as we have seen. The symmetry facilitates not only the comprehension of a form, but also its definition and construction, as we shall now show. Only a single part needs to be defined, since the other can be found by symmetrical repetition. This leads us to search for the minimal part of a RIGE that can generate the rest in this way. If it can be found, we will call it the Generative Element (GE) of this particular RIGE.
There is also a third type of symmetry in riges, a faked spatial (3-dimensional) one: when interlace is adopted (see the page that follows) the axial symmetry presents an alternative up and down (above/below) frame crossing which can be seen and understood as a spatial axial symmetry. The ideal procedure would then be to gyrate the GE round its symmetry axes, not in the plane, but rather in the space, as a door which emerges from the plane, and return to it after a 180 degree turn. This spatial procedure agrees with the psychological impression which interlace suggests: the RIGE escapes from the plane to which it belongs and adquires depth, relief, spatial existence.
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