Tutorial: Action Masking#


In many environments, it is natural for some actions to be invalid at certain times. For example, in a game of chess, it is impossible to move a pawn forward if it is already at the front of the board. In PettingZoo, we can use action masking to prevent invalid actions from being taken.

Action masking is a more natural way of handling invalid actions than having an action have no effect, which was how we handled bumping into walls in the previous tutorial.