The smallest number of elements that is non-trivial is three, and there are two 2-element-kind non-trivial transformations possible, one being both the reverse transformation and the topological dual, of the other.
Najmanji broj elemenata koji nije trivijalan je tri a postoje dve moguće dvoelementne transformacije koje nisu trivijalne, jedna je i obrnuta transformacija i topološki dual dual, druge.