Inter-module credit assignment in modular reinforcement learning

  • Authors:
  • Kazuyuki Samejima;Kenji Doya;Mitsuo Kawato

  • Affiliations:
  • Human information science laboratories, ATR International,2-2-2 Hikaridai, Seika, Soraku, Kyoto 619-0238, Japan and Creating the Brain, CREST, Japan Science and Technology Corporation,2-2-2 Hikari ...;Human information science laboratories, ATR International,2-2-2 Hikaridai, Seika, Soraku, Kyoto 619-0238, Japan and Creating the Brain, CREST, Japan Science and Technology Corporation,2-2-2 Hikari ...;Human information science laboratories, ATR International,2-2-2 Hikaridai, Seika, Soraku, Kyoto 619-0238, Japan

  • Venue:
  • Neural Networks
  • Year:
  • 2003

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Abstract

Critical issues in modular or hierarchical reinforcement learning (RL) are (i) how to decompose a task into sub-tasks, (ii) how to achieve independence of learning of sub-tasks, and (iii) how to assure optimality of the composite policy for the entire task. The second and last requirements are often under trade-off. We propose a method for propagating the reward for the entire task achievement between modules. This is done in the form of a 'modular reward', which is calculated from the temporal difference of the module gating signal and the value of the succeeding module. We implement modular reward for a multiple model-based reinforcement learning (MMRL) architecture and show its effectiveness in simulations of a pursuit task with hidden states and a continuous-time non-linear control task.