Author: KarinsDad
Date: 08:39:23 12/24/98
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A sudden thought occured. How do you handle zugzwang in a null move search? I could see how it would be a problem: Player A = computer Player B = opponent A is examining a move Ply x. B can counter with Ply x+1. B is given a null move; effectively, but not really Ply x+2. Every response by A at Ply x+3 results in the Ply x+2 move having a lower score than Ply x+1, hence we ran into zugzwang. However, how does one handle a more complex case such that zugzwang is not detected until Ply x+4 or Ply x+6? Zugzwang is often associated with only a few number of moves on the board (although that is not always the case). If the zugzwang would not be detected until Ply x+4, it seems that this would defeat the entire purpose of using a null move search (i.e. pruning the tree of moves that would be bad anyway). And how does this work when you do not run into zugzwang? Do you check for zugzwang by ignoring the results at Ply x+2 where that move results in either a piece capture or a piece promotion (and hence the score will jump materially towards the move being good as opposed to bad) and only look at the other moves? This is somewhat unclear and confusing. Can anyone explain it in a clear manner? Thanks, KarinsDad
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