Key Issues

• The search process constructs a search tree, where the root is the initial state and all of the leaf nodes are nodes that have not yet been expanded (i.e., they are in the list "nodes") or are nodes that have no successors (i.e., they're "deadends" because no operators were applicable and yet they are not goals).

• The search tree may be infinite because of loops even if state space is small.

• The search process returns a path or a node depending on problem, e.g. in cryptarithmetic it returns a node; in the 8-puzzle it returns a path.

• Changing the definition of the QUEUEING-FUNCTION leads to different search strategies.