An heuristic evaluation function is some form of guess at an intermediate state about the eventual outcome of a search. This is used in a heuristic search to act as a guide as to the best order to explore many different options. For example, whilst searching for shortest routes between places, we might use the Euclidean distance between two cities as a heuristic for the eventual shortest road distance well before we explore the potential routes between them.
Used on pages 63, 78, 221, 224, 531
Also known as heuristic evaluation