Author: Robert Hyatt
Date: 16:58:32 12/24/97
Go up one level in this thread
On December 24, 1997 at 17:58:58, Don Dailey wrote: >>I would amend the above to say "most pushes of passed pawns, *until you >>reach the endgame* are blunders." If you don't extend once material >>gets >>low, you can fall for lots of passed pawn tactics... and if you do it >>carefully, it doesn't have to be expensive. IE only extend safe passed >>pawn pushes (as verified by the SEE routine)... only extend when the >>opponent >>has few pieces left... and so forth... > >Hi Bob, > >I still believe MOST passed pawn pushes, even in the endgame are >blunders. But I do not necessarily mean they are immediately subject >to capture in which case I think I agree with you. The way I'm thinking >about it is simply from it's game theoretic value. In almost all >endings >involving pawns, the pawn is gradually nursed to the queening square >after lots of fits and starts and subtle maneuverings. In general it >has to be timed perfectly and most of the possible pawns pushes will >spoil the win. > >But as I said before, this may not be the point. Maybe the extension >will help us see that the pawn push spoils the win? To me this is >just as important as seeing that it wins. > >I am interested in your SEE routine. Can you elaborate on it? >From the context of your statement I'm guessing that it looks to >see if the sqaure the pawn wants to move to is safe from capture. >Is this what it does? > yes.. it is the same exchange evaluator (swap.c in crafty source) that I use to order/reject captures, etc... I simply make sure that if the pawn is pushed, it isn't subject to immediate loss (-1.00 in material terms).. that is, pushing it can't "hang" it for nothing, although pushing it to the 8th and promoting is ok if it is defended better than it is attacked.. so "safe from capture" could be confusing since it might be possible to rip it, but at a loss if you do... >I would like to do more passed pawn extensions in Cilkchess if >I can figure out the right way to do them. It sounds like you have >figured out how to do it farily well in Crafty. > > >- Don I'm simply following what I did in Cray Blitz as it seemed to work pretty well most of the time. I don't allow them until I reach an endgame situation however, as pushing them in the middlegame only blows up the search, while rarely accomplishing anything but dropping the pawn later on, as you suggest...
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