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Subject: Problems connected with hashing

Author: Jan Pernicka

Date: 04:41:57 09/08/00


 Hi,
summer is almost over and I return from holidays to Internet :)

I have just implemented (= and debugged) hashing in my chess program and
have to face (at least) 2 problems:

   1) How to update Best Variation when using hash?
       My solution: Do everything as normal and when transposition is detected,
                    trace (with help from best move saved in hash table)
                    partial best line through chain of positions in hash
                    table.

  2) (more "dangerous"): When detecting 3-fold repetition (in fact 2-fold)
     in the tree in position A - I return score=DRAW_SCORE and e.g. in the
     position (B) immediately above position A I store in hash table score
     which is influenced by score of position A, but this score (of A) is
     relative to the root(it is repetition): in position B - when it will
     occur somewhere else in the tree - it could cause errors.
     My solution: I simply ignore this fact.

 Thanks for your answers and have a nice day.

         Jan



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