Do other engines reproduce this blunder?

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Dr.Wael Deeb
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Re: Do other engines reproduce this blunder?

Post by Dr.Wael Deeb » Fri Mar 25, 2011 9:04 am

ernest wrote:
Dr.Wael Deeb wrote:Even a 1200 Elo player will be ashamed to make such a stupid blunder.....
Dr.D
A very clever and adequate post... :o
Too bad, lately you seemed to have recovered... Get well, Doctor!
It's true....I mean look at the move that has been made.....
We must be objective when we see something wrong,not blindly to stick to our most beloved chess engines....
Dr.D
_No one can hit as hard as life.But it ain’t about how hard you can hit.It’s about how hard you can get hit and keep moving forward.How much you can take and keep moving forward….

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Houdini
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Re: Do other engines reproduce this blunder?

Post by Houdini » Fri Mar 25, 2011 11:48 am

michiguel wrote:In addition, it means that Houdini in this game was used in "probe only at root" mode. If you probe in search, it is almost impossible that this bug will have a significant effect. I suggest that all engines that have a GTB probing code previous to 0.4 to be used with "probing in search" or whatever name the author gave for that feature.
How do you mean?
The root position is an EGTB position, no engine will ever perform any analysis other than consulting the TB to select the move with the shortest distance to mate.
In the position h7-h5 is clearly the best move if White doesn't know the en-passant rule :lol:.

Robert

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michiguel
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Re: Do other engines reproduce this blunder?

Post by michiguel » Fri Mar 25, 2011 12:46 pm

Houdini wrote:
michiguel wrote:In addition, it means that Houdini in this game was used in "probe only at root" mode. If you probe in search, it is almost impossible that this bug will have a significant effect. I suggest that all engines that have a GTB probing code previous to 0.4 to be used with "probing in search" or whatever name the author gave for that feature.
How do you mean?
The root position is an EGTB position, no engine will ever perform any analysis other than consulting the TB to select the move with the shortest distance to mate.
I guess I was very unclear (an possibly wrong).

What you call "consulting the EGTB" means a hidden one ply search, which exposes the bug with no chance to recover (because you are at the root with a EGTB position). When you do not have that situation and you could encounter the position in a deeper search, is more difficult that you face a problem. That is because the search should stop at the previous ply (because it is also an EGTB position). That is what I mean. This is because ep "generating" moves are not captures that could transition from a non EGTB position to an EGTB position.

If the engine probes in search, most likely won't see any ep position at all. This is true. Maybe, during a game, the engine would avoid reaching positions like this at the root, rather than avoiding the bug itself. But I am not so sure now and I may be wrong.

The bug is exposed at positions in the root, when black is a pawn ahead in a KPKPP positions (KPPKP is fine), and black plays a move that white could capture ep. If you probe in search, In addition, the root position must have been the best position from previous searches. That may add an extra condition that could make reaching this problem more a bit more unlikely, but it is not guaranteed.

Anyway, the real solution is to download the bugfix.
Miguel
In the position h7-h5 is clearly the best move if White doesn't know the en-passant rule :lol:.

Robert

Uri Blass
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Re: Do other engines reproduce this blunder?

Post by Uri Blass » Fri Mar 25, 2011 1:45 pm

Dr.Wael Deeb wrote:Even a 1200 Elo player will be ashamed to make such a stupid blunder.....
Dr.D
In this case he can feel better after knowing that even
Ruslan Ponomariov did a blunder because of forgetting the enpassent rule against Fritz.

http://chessgames.com/perl/chessgame?gid=1371049

Roger Brown
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Re: Do other engines reproduce this blunder?

Post by Roger Brown » Fri Mar 25, 2011 4:37 pm

michiguel wrote:
SNIP

Miguel
PS: Why this post is here in this subforum?


Hello Miguel,

Probably the o.p. thought that any Houdini post = Origins sub-form.

Moved forthwith to Technical subforum.

Later.

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marcelk
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Re: Do other engines reproduce this blunder?

Post by marcelk » Fri Mar 25, 2011 4:41 pm

Roger Brown wrote:
michiguel wrote:
SNIP

Miguel
PS: Why this post is here in this subforum?


Hello Miguel,

Probably the o.p. thought that any Houdini post = Origins sub-form.

Moved forthwith.

Later.
Indeed that is what I thought. I find it mildly amusing that the Gaviota author has to explain to the Houdini author how his program works with EGTBs from root.

rbarreira
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Re: Do other engines reproduce this blunder?

Post by rbarreira » Fri Mar 25, 2011 5:12 pm

marcelk wrote:
Roger Brown wrote:
michiguel wrote:
SNIP

Miguel
PS: Why this post is here in this subforum?


Hello Miguel,

Probably the o.p. thought that any Houdini post = Origins sub-form.

Moved forthwith.

Later.
Indeed that is what I thought. I find it mildly amusing that the Gaviota author has to explain to the Houdini author how his program works with EGTBs from root.
It's not so amusing if you know anything about programming (do you?). Bugs in external libraries used by your code are not always understandable without help from the library's author.

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Houdini
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Re: Do other engines reproduce this blunder?

Post by Houdini » Fri Mar 25, 2011 6:15 pm

marcelk wrote:Indeed that is what I thought. I find it mildly amusing that the Gaviota author has to explain to the Houdini author how his program works with EGTBs from root.
You seem to have misunderstood the discussion.
My post was intended to correct Miguel's assertion that the occurrence of the error was related to a "probe only at root" mode which, by the way, doesn't even exist in Houdini.

Robert

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Houdini
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Re: Do other engines reproduce this blunder?

Post by Houdini » Fri Mar 25, 2011 6:26 pm

rbarreira wrote:It's not so amusing if you know anything about programming (do you?). Bugs in external libraries used by your code are not always understandable without help from the library's author.
The Gaviota EGTB probing code is quite clear and self-explanatory.
Sometimes we can even help the author of the library to correct a bug, see for example this thread.

Robert

rbarreira
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Re: Do other engines reproduce this blunder?

Post by rbarreira » Fri Mar 25, 2011 7:01 pm

Houdini wrote:
rbarreira wrote:It's not so amusing if you know anything about programming (do you?). Bugs in external libraries used by your code are not always understandable without help from the library's author.
The Gaviota EGTB probing code is quite clear and self-explanatory.
Sometimes we can even help the author of the library to correct a bug, see for example this thread.

Robert
Sure. I was responding to Marcel's general point...

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