An Exact Score is a score returned from an alpha-beta search, if alpha, the max so far, was improved, while the min-player improved his score as well (score < beta). The current node searched was an expected PV-Node, which was confirmed by the search in finding and collecting a principal variation.
Always or Never
- Bounds... when is an exact score an EXACT score? by Ross Boyd, CCC, August 01, 2003
- A few general questions... by Bill Henry, CCC, January 29, 2012 » Root, Aspiration Windows