Editing Self-modifying code (section)

===Self-referential machine learning systems===
Traditional [[machine learning]] systems have a fixed, pre-programmed learning [[algorithm]] to adjust their [[parameter (computer programming)|parameter]]s. However, since the 1980s [[Jürgen Schmidhuber]] has published several self-modifying systems with the ability to change their own learning algorithm. They avoid the danger of catastrophic self-rewrites by making sure that self-modifications will survive only if they are useful according to a user-given [[fitness function|fitness]], [[error function|error]] or [[reward function|reward]] function.<ref name="Schmidhuber"/>