Intelligent agents Intelligent agents are supposed to act in such a way that the environment goes through a sequence of states that maximizes the performance measure. Goal = a set of world states in which some measure is satisfied Actions = cause transitions between world states An agent has to choose or discover actions that get it to its goal state. From a given world state there will be a certain set of world states which are reachable. Taking an action can be viewed as pruning/changing the set of available world states an agent can reach from the current world state. Final evaluation of an agent’s problem solving performance – goodness of solution vs. cost of finding it..

Things a goal oriented agent might want to know

Does the agent need to know the current world state? What if sensors, other are damaged? Fault tolerance – ability to deal with a damaged agent, sensors on vacuum go bad World state accessible, vacuum performs as advertised. No percepts, vacuum performs as advertised. World state accessible, vacuum coughs up dirt if floor clean Only local sensors, vacuum coughs up dirt if floor clean – a contingency problem. Single state and mult-state problems can be handled by relatively simple search techniques, while contingency problems require more complicated algorithms. The agent must also be able to act before it has found a guaranteed solution. Problem Formulation – The Vacuum world

Defining Single State Problems

What happens if part of the puzzle is not visible? What if I know where the blank is, and when I exchange the blank with something I find out what that something is? What if I don’t know where the blank is, but when I exchange the blank with something I find out what that something is? Problem Formulation – The 8 Puzzle (see pdf)

Real world is absurdly complex – state space must be abstracted (Abstract) state = set of real states (Abstract) operator = complex combination of real actions (Abstract) solution = solves the problem in the real world Each abstract action should be “easier” than the original problem Selecting a state space for real world problems

Three missionaries and three cannibals on the left bank of a river seek to cross the river to the right bank. They have a boat which can carry up to two people at a time. All missionaries and cannibals are able to row the boat. If at any time the cannibals outnumber the missionaries on either bank the cannibals will eat the missionaries Now find a way to get EVERYONE to the other side. Problem Formulation – Missionaries and Cannibals