termination functions, allow [OOIs]{}to be used without any domain knowledge.

Motivating Example {#sec:motivation}
------------------

![Robotic object gathering task. a) Khepera III, the two-wheeled robot used in the experiments. b) The robot has to gather objects from two terminals separated by a wall, and to bring them to the root.[]{data-label="fig:khepera"}](figures/khepera_terminals)

[OOIs]{}are designed to solve complex partially-observable tasks that can be decomposed into a set of fully-observable sub-tasks. For instance, a robot with first-person sensors may be able to avoid obstacles, open doors or manipulate objects even if its precise location in the building is not observed. We now introduce such an environment, on which our robotic experiments of Section \[sec:khepera\] are based.

A Khepera III robothas to gather objects from two terminals separated by a wall, and to bring them to the root (see Figure \[fig:khepera\]). Objects have to be gathered one by one from a terminal until it becomes empty, which requires many journeys between the root and a terminal. When a terminal is emptied, the other one is automatically refilled. The robot therefore has to alternatively gather objects from both terminals, and the episode finishes after the terminals have been emptied some random number of times. The root is 