Best-First Search
Similar to Depth-first and breadth-first searches.
However, the list OPEN is maintained as a priority queue, with each state s on OPEN having a “heuristic value” f(s) such that the smaller f(s) is, the higher is the priority of that state for expansion.
f(s) reflects an estimated “cost” of the state s. It can also be thought of as an estimate of a sort of distance between s and the nearest goal state.
e.g., “longitude difference” estimates the distance between two cities.