The correct answer is: Implicit.
Implicit functions are used as preferences over state history because they are more flexible than explicit functions. Implicit functions can be used to represent a wide range of preferences, including those that are difficult to articulate explicitly. Additionally, implicit functions can be used to model the preferences of multiple agents, which can be difficult to do with explicit functions.
Explicit functions, on the other hand, are more difficult to use because they require the user to specify their preferences in a precise way. This can be difficult to do, especially if the user’s preferences are complex or if they
are not sure what their preferences are. Additionally, explicit functions can be difficult to modify if the user’s preferences change.Award and reward are not functions, but rather actions that can be taken to influence the preferences of an agent. Awarding an agent with a prize or reward can make them more likely to take actions that are consistent with the agent’s preferences. However, awards and rewards can also be used to manipulate the preferences of an agent, which can be unethical.
Explicit functions are functions that are defined in a clear and unambiguous way. They can be used to represent a wide range of preferences, but they can be difficult to use if the user’s preferences are complex or if they are not sure what their preferences are. Additionally, explicit functions can be difficult to modify if the user’s preferences change.