Before revision:  The path planning problem is translated into a decentralized partially observable Markov decision process (Dec-POMDP), which we solve by training a double deep Q-network (DDQN) to approximate the optimal UAV control policy  .
After revision:  The path planning problem is translated into a decentralized partially observable Markov decision process (Dec-POMDP), which we solve through a deep reinforcement learning (DRL) approach, approximating the optimal UAV control policy .