One Decade of Universal Artificial Intelligence
  The first decade of this century has seen the nascency of the first
mathematical theory of general artificial intelligence. This theory of
Universal Artificial Intelligence (UAI) has made significant contributions to
many theoretical, philosophical, and practical AI questions. In a series of
papers culminating in book (Hutter, 2005), an exciting sound and complete
mathematical model for a super intelligent agent (AIXI) has been developed and
rigorously analyzed. While nowadays most AI researchers avoid discussing
intelligence, the award-winning PhD thesis (Legg, 2008) provided the
philosophical embedding and investigated the UAI-based universal measure of
rational intelligence, which is formal, objective and non-anthropocentric.
Recently, effective approximations of AIXI have been derived and experimentally
investigated in JAIR paper (Veness et al. 2011). This practical breakthrough
has resulted in some impressive applications, finally muting earlier critique
that UAI is only a theory. For the first time, without providing any domain
knowledge, the same agent is able to self-adapt to a diverse range of
interactive environments. For instance, AIXI is able to learn from scratch to
play TicTacToe, Pacman, Kuhn Poker, and other games by trial and error, without
even providing the rules of the games.
  These achievements give new hope that the grand goal of Artificial General
Intelligence is not elusive.
  This article provides an informal overview of UAI in context. It attempts to
gently introduce a very theoretical, formal, and mathematical subject, and
discusses philosophical and technical ingredients, traits of intelligence, some
social questions, and the past and future of UAI.
