Sequential Problem Solving by Hierarchical Planning in Latent Spaces

Sequential problem solving is a remarkable ability demonstrated by humans and other intelligent animals. For example, a behavioral ecology study has shown how a crow can plan to retrieve a stone and drop it into the box. This is not an easy task since the stone is initially placed in a cage and the crow cannot get through the bars. But the crow intelligently makes its way to the goal by sequentially picking up a stick, using the stick to reach the stone, and taking the stone to the goal location. In each step, the crow interacts with the environment in a different way which eventually serves the goal of the task. These steps need to be carefully composed together in a specific order, such that the stick will be picked up before being used for reaching the stone.