Learning Task-Specific State Representations by Maximizing Slowness and Predictability. Jonschkowski, Brock. International Workshop on Evolutionary and Reinforcement Learning for Autonomous Robot Systems (ERLARS) 2013

Referenced from here: https://aresearch.wordpress.com/2015/04/17/autonomous-learning-of-state-representations-for-control-an-emerging-field-aims-to-autonomously-learn-state-representations-for-reinforcement-learning-agents-from-their-real-world-sensor-observations/

1. As the title suggests, discusses setting up an NN that optimizes for predictability and slowness
2. In addition to normal criteria for learned representation (allows rep of value function, allows original representation to be reproduced, allows for Markov property/prediction) they add a couple of other criteria:
   1.  Slowness
   2. Allows for transfer
3. Consider fully observable tasks
4. Also requires that representation is diverse (this exists in SFA to prevent trivial constant output)
5. Formally, the cost function has 3 terms added together:
   1. Slowness (representation changes only a small amount between two subsequent steps)
   2. Diversity (states farther in time should be mapped farther apart)
   3. Transition function (must allow for accurate prediction of next state, given state, action)
6. The representation learned according to this criteria is then used to learn the Q function
7. The domain this is tested in is a racetrack domain -the rep is a graphical 10×10 overhead greyscale <doesnt seem so hard, but this is just a workshop paper>