Explainable Artificial Intelligence for Reinforcement Learning Agents
Sammanfattning: Following the success that machine learning has enjoyed over the last decade, reinforcement learning has become a prime research area for automation and solving complex tasks. Ranging from playing video games at a professional level to robots collaborating in picking goods in warehouses, the applications of reinforcement learning are numerous. The systems are however, very complex and the understanding of why the reinforcement learning agents solve the tasks given to them in certain ways are still largely unknown to the human observer. This makes the actual use of the agents limited to non-critical tasks and the information that could be learnt by them hidden. To this end, explainable artificial intelligence (XAI) has been a topic that has received more attention in the last couple of years, in an attempt to be able to explain the machine learning systems to the human operators. In this thesis we propose to use model-agnostic XAI techniques combined with clustering techniques on simple Atari games, as well as proposing an automated evaluation for how well the explanations explain the behavior of the agents. This in an effort to uncover to what extent model-agnostic XAI can be used to gain insight into the behavior of reinforcement learning agents. The tested methods were RISE, t-SNE and Deletion. The methods were evaluated on several different agents trained on playing the Atari-breakout game and the results show that they can be used to explain the behavior of the agents on a local level (one individual frame of a game sequence), global (behavior over the entire game sequence) as well as uncovering different strategies used by the agents and as training time differs between agents.
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