In this context, ‘robustly’ means that even with small changes to the system (such as moving the agent or the goal to a different location in a maze) the agent still achieves the goal. If you think of the system state as a location in a phase space, this could look like a large “basin of attraction” of initial states that all converge to the goal state.
If we take a marble and a bowl, and we place the marble at any point in the bowl, it will tend to roll towards the middle of the bowl. In this case “phase space” and “physical space” map very closely to each other, and the “basin of attraction” is quite literally a basin. Still, I don’t think most people would consider the marble to be an “agent” that “robustly optimizes for the goal of being in the bottom of the bowl”.
However, while I’ve got a lot of concrete examples of things which are definitely not agents (like the above) or “maybe kinda agent-like but definitely not central” (e.g. a minmaxing tic-tac-toe program that finds the optimal move by exploring the full game tree, or an e-coli bacterium which uses run-and-tumble motion to increase the fraction of the time it spends in favorable environments, a person setting and then achieving career goals), I don’t think I have a crisp central example of a thing that exists in the real world that is definitely an agent.
In this context, ‘robustly’ means that even with small changes to the system (such as moving the agent or the goal to a different location in a maze) the agent still achieves the goal. If you think of the system state as a location in a phase space, this could look like a large “basin of attraction” of initial states that all converge to the goal state.
If we take a marble and a bowl, and we place the marble at any point in the bowl, it will tend to roll towards the middle of the bowl. In this case “phase space” and “physical space” map very closely to each other, and the “basin of attraction” is quite literally a basin. Still, I don’t think most people would consider the marble to be an “agent” that “robustly optimizes for the goal of being in the bottom of the bowl”.
However, while I’ve got a lot of concrete examples of things which are definitely not agents (like the above) or “maybe kinda agent-like but definitely not central” (e.g. a minmaxing tic-tac-toe program that finds the optimal move by exploring the full game tree, or an e-coli bacterium which uses run-and-tumble motion to increase the fraction of the time it spends in favorable environments, a person setting and then achieving career goals), I don’t think I have a crisp central example of a thing that exists in the real world that is definitely an agent.