changes.txt

Version 1.0:

Alpha beta search
Evaluation function - counts number of possible connect 4 for each player.

Version 1.1:

Transposition table added (misspelled as transition table).
Two hash values are kept updated, such that a mirrored position is also recognized.

Version 1.2:

"Best move" added to transposition table. Internal iterative deepening.
Two hash tables are used - one for short depth and one for high depth.
The idea is that the entries in the high depth one should not be deleted.
New hash table used for storing an opening library.

Version 1.3:

Opening library completed. Plays optimal, but does not necessarily win
in the fewest number of moves. Can now also play with normal rules
(cannot play optimal) or where the aim is to get a square (with optimal play).

Version 1.3.1:

Cannot remember what was changed since 1.3 and haven't bothered to find out.