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Subject: Tree reduction and search depth question

Author: José Carlos

Date: 01:30:20 08/10/01


  After completely rewriting my chess program (Averno), I've run into the
null-move world, which I haddn't in old versions.
  In old Averno I had:

  -Reasonably good move ordering (hash move; good captures; killers; ...)
  -Transposition table
  -2 killers
  -Lazy eval
  -Check and recapture extension
  -Some out-of-check stuff in qsearch

  With that, I was searching 6-7 plies in blitz (in midgame) and 7-9 in
standard. [Athlon 550]

  I've read some open source programs to get a clue on how to search deeper, and
now I have:

  -Nullmove (tried R=3 and R=2, not yet R=2/3)
  -Futility pruning
  -Same move ordering as before
  -Same hashing scheme
  -Same 2 killers
  -Same Lazy eval
  -Check and null-threat extension
  -No out-of-check stuff in qsearch

  And now, I search 7-8 plies in blitz and 8-10 in standard (and the worst thing
is that the program looks weaker than the old one!)
  That looks like a poor search depth, isn't it? So what am I missing to get, as
most null-movers, 12-13 in standard?
  SEE? History heuristic for move ordering? ETC? Razoring?
  Sorry for _answering_ instead of _trying_ but, as I have so little free time
to work on my program, any advice would be appreciated.
  As well, I'd like to know if, with the stuff I've implemented so far, I should
expect a better performance. In that case, I might have a bug somewhere.

  Thanks in advance,

  José C.



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