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Joona Kiiski

Joined: 18 Jan 2009
Posts: 546

Post subject: Re: For Marco---possible Stockfish bug    Posted: Wed Feb 01, 2012 8:32 pm

lech wrote:
I changed (in Stockfish 2.1.1)

 Code: if (!Root && value > alpha)           {               if (PvNode && value < beta) // We want always alpha < beta {                   alpha = value;

to:

 Code: if (!Root && value > alpha)           {               if (PvNode && value <= beta) // We want always alpha < beta {                   alpha = value;

And now Stockfish can solve this position.
My theory has the position, which should be solved by Stockfish.
8th point in search give a right to watch the solution.
My theory says, that in pvnode it would be good to accept alpha = beta.
I changed the code (above) and Stockfish solved this position.
I think it is a very interesting theme for programmers.

The problem is that modern chess engines are very chaotic process. Changing one piece-square table value by one unit could as well make SF to solve the position.

By making to SF to solve one specific position, one can justify almost any change. What we need is a logical reasoning: why do you think that algorithmically it's better to allow alpha := beta. Give one (hypothetic) example situation where this could make positive difference.
_________________
Joona Kiiski
 Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First
Subject Author Date/Time
Louis Zulli Tue Jan 31, 2012 5:49 pm
Marco Costalba Tue Jan 31, 2012 7:12 pm
Joona Kiiski Wed Feb 01, 2012 7:56 am
Marek Kwiatkowski Wed Feb 01, 2012 10:02 am
Joona Kiiski Wed Feb 01, 2012 12:48 pm
Louis Zulli Wed Feb 01, 2012 2:41 pm
Marek Kwiatkowski Wed Feb 01, 2012 7:15 pm
Marco Costalba Wed Feb 01, 2012 7:23 pm
Marek Kwiatkowski Wed Feb 01, 2012 9:05 pm
Re: For Marco---possible Stockfish bug Joona Kiiski Wed Feb 01, 2012 8:32 pm
Marek Kwiatkowski Wed Feb 01, 2012 9:02 pm
Joona Kiiski Thu Feb 02, 2012 8:30 am
Marek Kwiatkowski Thu Feb 02, 2012 8:36 am
Joona Kiiski Thu Feb 02, 2012 10:52 am
Marek Kwiatkowski Thu Feb 02, 2012 2:08 pm
Joona Kiiski Thu Feb 02, 2012 3:45 pm
Marek Kwiatkowski Thu Feb 02, 2012 5:32 pm
david nash Thu Feb 02, 2012 6:14 pm
Richard Vida Thu Feb 02, 2012 7:23 pm
Marco Costalba Thu Feb 02, 2012 8:04 pm
Robert Wagner Campos Thu Feb 02, 2012 8:59 pm
Uri Blass Thu Feb 02, 2012 10:41 pm
Marek Kwiatkowski Thu Feb 02, 2012 9:01 pm
Sven Schüle Thu Feb 02, 2012 11:28 pm
Robert Wagner Campos Fri Feb 03, 2012 12:26 pm
Uri Blass Fri Feb 03, 2012 2:14 pm
Marek Kwiatkowski Fri Feb 03, 2012 2:21 pm
Evert Glebbeek Fri Feb 03, 2012 2:41 pm
Marek Kwiatkowski Fri Feb 03, 2012 2:58 pm
Sam Hamilton Fri Feb 03, 2012 3:23 pm
Evert Glebbeek Sat Feb 04, 2012 7:07 am
Marek Kwiatkowski Sat Feb 04, 2012 9:31 am
Marek Kwiatkowski Sun Feb 05, 2012 4:20 pm
Marek Kwiatkowski Sun Feb 05, 2012 5:24 pm
Marek Kwiatkowski Wed Feb 08, 2012 1:54 pm
Joerg Oster Wed Feb 08, 2012 5:14 pm
Marek Kwiatkowski Wed Feb 08, 2012 5:49 pm
Marek Kwiatkowski Sun Feb 19, 2012 5:37 pm
Robert Wagner Campos Fri Feb 03, 2012 6:33 pm
Robert Wagner Campos Fri Feb 03, 2012 6:15 pm
Louis Zulli Sat Feb 04, 2012 1:50 am
Marek Kwiatkowski Fri Feb 03, 2012 2:08 pm
Kevin Hearn Fri Feb 03, 2012 3:49 pm
Marek Kwiatkowski Fri Feb 03, 2012 6:45 pm
Joerg Oster Wed Feb 01, 2012 8:38 pm
Louis Zulli Wed Feb 01, 2012 9:14 pm
Joerg Oster Thu Feb 02, 2012 7:23 am
Marek Kwiatkowski Thu Feb 02, 2012 8:29 am
Louis Zulli Wed Feb 01, 2012 9:38 pm
Marek Kwiatkowski Wed Feb 01, 2012 9:54 pm
Louis Zulli Wed Feb 01, 2012 11:05 pm
Marek Kwiatkowski Wed Feb 01, 2012 11:11 pm

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