Author: Robert Hyatt
Date: 11:56:19 01/20/04
Go up one level in this thread
On January 20, 2004 at 13:22:18, Sune Fischer wrote: >On January 20, 2004 at 12:01:59, Robert Hyatt wrote: > >>Then Grandmasters are producing tons of "eye candy" every day as they >>merrily annotate games and give variations. Are you really a chess player? >>IE I want analysis, not just "white is better" myself. > >Yes I am really a chess player, and I know how to analyze using an engine. > >You need to go back and forth down the lines that look interesting. > >Particularly big sacrifices can take a while for engines to see, they fail high >10 times faster if you just execute the move so nullmove and other pruning >devices gets a better root window to work with. I rarely use that approach, as it doesn't prove the sacrifice was the best move at the root position if you force the game a few moves down... > >>>It never shows you all the refutations, say there is a queen en prised on the >>>board, the PV at iteration 5 shows us taking it but at ply 6 we get a completely >>>new line. >>>Why can't we take the queen, what's wrong with that, what did the engine see? >> >> >>That is obtainable, if you want to know. You just step down the PV to the >>point in question (you _do_ have a PV to step down, right, otherwise you would >>not even know the queen is hanging except by the score maybe) and then let the >>search show you the PV for the move you are questioning. > >If you have lost the first half of the pv how are you going to track it? you search down to the end of the PV, and then go forward. The engine is going to follow the same path again... > >>> >>>That's what I want to know, as a chessplayer :) >>> >> >>Me too and that is what I get by having the PV displayed. With just a best >>move or best move and sometimes random moves below it being shown, I have a >>harder time. Just note the people that started this thread. Obviously it >>meant something to them... > >Looks to me like Shredder is a bit of an extreme example. >You have the same problem though if you can't resolve a fail high, no pv :) I can _always_ resolve a fail-high. The question is, do I want to take the time or can I take the time? But if someone wants to see the score or PV, they can wait and get it eventually... Here you are mixing the concepts of playing a game and analyzing an old game. When playing a game, you play the best move. When analyzing you want more than just a best move. IE why print the score either? > >>Mine almost always goes to the leaf position. On occasion it gets cut short, >>but that is the exception rather than the rule. > >Even after the search has being going on for a while and there are lots of good >hash entries? > Yes. If you got lots of short PVs it suggests a problem. Alpha/beta prunes on >= or <=, not just > or <. In some positions, the problme can't be avoided. Fine 70 comes to mind. >>In tactical positions I trust the PV to the end. IE mate in 15 is not going >>to be flakey near the end. Nor is winning a pawn or piece, or promoting >>something... >> >>So it is not as useless as you seem to think. > >The hash shows the same behavior on tactical positions. > >-S. again, not always.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.