Author: Robert Hyatt
Date: 17:31:49 07/16/02
Go up one level in this thread
On July 16, 2002 at 18:39:53, Gerd Isenberg wrote: >On July 16, 2002 at 18:25:08, Robert Hyatt wrote: > >>On July 16, 2002 at 18:10:59, Uri Blass wrote: >> >>>On July 16, 2002 at 17:44:36, Robert Hyatt wrote: >>> >>>>On July 16, 2002 at 17:38:02, Uri Blass wrote: >>>> >>>>>On July 16, 2002 at 16:52:33, Robert Hyatt wrote: >>>>> >>>>>>On July 16, 2002 at 14:32:57, Russell Reagan wrote: >>>>>> >>>>>>>On July 16, 2002 at 11:07:10, Robert Hyatt wrote: >>>>>>> >>>>>>>>However, with _no_ book you leave yourself open for preparation of traps. I >>>>>>>>saw Ken Thompson do this to NuChess years ago at an ACM event. You don't want >>>>>>>>to leave that kind of "hole" for a major event... >>>>>>> >>>>>>>Was it a trap set specifically for that engine? Or was it just a general trap >>>>>>>that many engines fall for when left on their own? >>>>>>> >>>>>>>Russell >>>>>> >>>>>> >>>>>>Sort of both. >>>>>> >>>>>>1. Ken knew which opening Nuchess would play, as ken was white and they >>>>>>had a pretty narrow book. He simply added a line that made them go out of >>>>>>book pretty early, with a classic trap where they gave up a piece to win >>>>>>the rook at a1, and thought they were winning an exchange and losing a pawn. >>>>>>In reality, they lost both pieces plus the pawn, and the game. >>>>> >>>>>It is not going to work against Movei even in bullet. >>>>> >>>>>Movei evaluates black knight at a1 as clearly less than a knight in normal >>>>>squares and the difference in evaluation is slightly more than a pawn. >>>> >>>>Look out on ICC. Would you rather lose a pawn or be forced to place your >>>>knight on A1/H1 for a while? I would prefer to stick the knight on the >>>>corner, because that can be corrected later. Losing the pawn is losing the >>>>pawn, period. You can't make it come back later. >>> >>>There are often cases when the black knight cannot come out of a1 later. >>> >>>I prefer to lose a pawn for a probability of 40% to win the knight and I suspect >>>that it is more than 40%. >>> >>>If the knight is not trapped there is a good chance that the search can get it >>>out of the corner and it is easier relative to the case that the knight is >>>trapped because if it is trapped you may need many moves to capture it and in >>>most of the cases when it is not trapped you can get it out of the corner in one >>>move. >>> >>>I also saw games when Movei beated other programs because the knight of the >>>opponent was trapped in the corner. >>> >>>I think that these cases are more common then the cases when Movei is losing >>>games because it evaluates the corner too much. >>> >>>Uri >> >> >>I used to have a much larger corner penalty. And found on a few occasions >>that playing Nh1 to defend the pawn on f2 was the right move. But the program >>refused to do so because it thought that having the knight on H1 was worse than >>losing the pawn on f2. It was unfortunately mistaken. :) >> >>Big positional scores are perfectly OK. But you had better be sure that they >>don't have outlandish side-effects. This one sounds like it will... at a time >>when you least expect it. > >Did you mean a white knight on H1? >May be the corner penalty makes more sence with white pawns on A8 or H8 only, >where they are likely to get trapped. I thought Uri said "corner squares". Which is more dangerous than "corner squares on the enemy side of the board". But even then there are probably ways to exploit a program that thinks a knight on a8 is really bad...
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