Some computations allow shortcuts which can be used to speed them up. Consider the operation of raising a number to a positive integer
power. It is possible, for example, to calculate by multiplying 13 by itself seven times,
However, the shortcut of squaring three times considerably speeds up the computation,
It is often quite difficult to determine whether a given computation can be sped up by means of such a trick. Computations that cannot be sped up are said to exhibit
computational irreducibility.