21. To ensure predictability, all aperiodic messages must be included in the bandwidth management calculations. 22. Penrose had discovered two simple sets of aperiodic tiles, each consisting of just two quadrilaterals. 23. He calls this an aperiodic crystal. 24. A finite-state automaton is counter-free if and only if it is aperiodic . 25. An "'aperiodic sequence "'is one which is not ultimately periodic. 26. The best-known examples of an aperiodic set of tiles are the various Penrose tiles. 27. The known aperiodic sets of prototiles are seen on the list of aperiodic sets of tiles. 28. The known aperiodic sets of prototiles are seen on the list of aperiodic sets of tiles. 29. In 1988, Peter Schmitt discovered a single aperiodic prototile in 3-dimensional Euclidean space. 30. They belong to a general class of aperiodic tilings, which use tiles that cannot tessellate periodically.
