PVS extension up

Discussion of chess software programming and technical issues.

Moderators: hgm, Harvey Williamson, bob

Forum rules
This textbox is used to restore diagrams posted with the [d] tag before the upgrade.
ed

PVS extension up

Post by ed » Thu Jun 21, 2007 11:39 am

When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed

Michael Sherwin
Posts: 2911
Joined: Fri May 26, 2006 1:00 am
Location: OH, USA

Re: PVS extension up

Post by Michael Sherwin » Thu Jun 21, 2007 4:02 pm

ed wrote:When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed
Hi Ed,

Yes I have tried that type extention and it was inconclusive.

About extentions in general. When I first released RomiChess it only had a check extention and a mate threat extention and was already a rather strong program. I thought that if now, I were to put in all the right extentions, then it would take another big jump in ELO. However, no further extentions helped. I was getting very frustrated. Then Prof. Hyatt wrote that he was dropping some extentions as modern hardware was so fast that the extentions no longer helped and may even be counter productive. Given my experiance, I tend to agree.

Mike
Regards,
Mike

Tony

Re: PVS extension up

Post by Tony » Thu Jun 21, 2007 6:16 pm

Michael Sherwin wrote:
ed wrote:When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed
Hi Ed,

Yes I have tried that type extention and it was inconclusive.

About extentions in general. When I first released RomiChess it only had a check extention and a mate threat extention and was already a rather strong program. I thought that if now, I were to put in all the right extentions, then it would take another big jump in ELO. However, no further extentions helped. I was getting very frustrated. Then Prof. Hyatt wrote that he was dropping some extentions as modern hardware was so fast that the extentions no longer helped and may even be counter productive. Given my experiance, I tend to agree.

Mike
Check extensions seem to be the only ones that are clear winners. After that, they bring a lot less, and they seem to need retesting after every engine change.

Tony

Tony

Re: PVS extension up

Post by Tony » Thu Jun 21, 2007 6:26 pm

ed wrote:When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed
Hi Ed,

you wrote you're not happy with the passed pawns scoring.

Maybe you left out some stuff for simplicity, but there seems to be a major flaw in your scoring.
When a passed pawn is defended from behind by a rook (or queen) it will not show up in your attackboard on the square ahead of the pawn. So the pawn might look like it can't advance while it actually could.

Tony

Tony

Re: PVS extension up

Post by Tony » Thu Jun 21, 2007 6:28 pm

ed wrote:When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed
Hi Ed,

the
if (BB[rank+1] && WB[rank+1]) break;
stuff, should be
if (BB[rank+1] && !WB[rank+1]) break;
Tony

ed

Re: PVS extension up

Post by ed » Thu Jun 21, 2007 8:55 pm

Tony wrote:
ed wrote:When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed
Hi Ed,

you wrote you're not happy with the passed pawns scoring.

Maybe you left out some stuff for simplicity, but there seems to be a major flaw in your scoring.
When a passed pawn is defended from behind by a rook (or queen) it will not show up in your attackboard on the square ahead of the pawn. So the pawn might look like it can't advance while it actually could.

Tony
Good thinking Tony, I see you have done your homework quite well :D but..........

Something I did not describe (because I believe it is out of the realm of the page) is that during the scanning WB (and BB) are updated too in case of a vertical xray of a white rook and white pawn, that is, if the square is empty.

Example: from the start position, squares h3, h4 and h5 are incremented with 1 because of the xray wrh1 and wph2.

To be complete: I don't do it for Queens because queens are supposed to support a passed pawn in front, contrary to rooks.

Ed

ed

Re: PVS extension up

Post by ed » Thu Jun 21, 2007 9:03 pm

You are absolutely right, wrong ASM to C translation!

Thx

Ed

Tony wrote:
ed wrote:When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed
Hi Ed,

the
if (BB[rank+1] && WB[rank+1]) break;
stuff, should be
if (BB[rank+1] && !WB[rank+1]) break;
Tony

ed

Re: PVS extension up

Post by ed » Sun Jun 24, 2007 7:39 am

Michael Sherwin wrote:
ed wrote:When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed
Hi Ed,

Yes I have tried that type extention and it was inconclusive.

About extentions in general. When I first released RomiChess it only had a check extention and a mate threat extention and was already a rather strong program. I thought that if now, I were to put in all the right extentions, then it would take another big jump in ELO. However, no further extentions helped. I was getting very frustrated. Then Prof. Hyatt wrote that he was dropping some extentions as modern hardware was so fast that the extentions no longer helped and may even be counter productive. Given my experiance, I tend to agree.

Mike
Hi Mike,

The subject awakened my curiosity and so I ran a quick eng-eng match without the PVS extension. The result was considerable worse than with the default setting (PVS=ON). So it seems the PVS extension is still working.

Ed

Tony

Re: PVS extension up

Post by Tony » Sun Jun 24, 2007 8:57 am

ed wrote:
Michael Sherwin wrote:
ed wrote:When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed
Hi Ed,

Yes I have tried that type extention and it was inconclusive.

About extentions in general. When I first released RomiChess it only had a check extention and a mate threat extention and was already a rather strong program. I thought that if now, I were to put in all the right extentions, then it would take another big jump in ELO. However, no further extentions helped. I was getting very frustrated. Then Prof. Hyatt wrote that he was dropping some extentions as modern hardware was so fast that the extentions no longer helped and may even be counter productive. Given my experiance, I tend to agree.

Mike
Hi Mike,

The subject awakened my curiosity and so I ran a quick eng-eng match without the PVS extension. The result was considerable worse than with the default setting (PVS=ON). So it seems the PVS extension is still working.

Ed
I was wondering how you get 2 moves in a row from hashtable. One of the 2 positions would be a fail low node where you normally don't have a hashmove.

Do you store bestmoves in fail low nodes ? Or do you keep the bestmoves on fail low nodes when they previously were fail highs nodes ?

Tony

Uri Blass
Posts: 8334
Joined: Wed Mar 08, 2006 11:37 pm
Location: Tel-Aviv Israel

Re: PVS extension up

Post by Uri Blass » Sun Jun 24, 2007 9:10 am

Tony wrote:
ed wrote:
Michael Sherwin wrote:
ed wrote:When picking up my work again on the chess page I to my astonishment noticed I had forgotten to mention a probable important extension. I am curious how many of you use a similar approach.

http://www.top-5000.nl/authors/rebel/chess840.htm

Ed
Hi Ed,

Yes I have tried that type extention and it was inconclusive.

About extentions in general. When I first released RomiChess it only had a check extention and a mate threat extention and was already a rather strong program. I thought that if now, I were to put in all the right extentions, then it would take another big jump in ELO. However, no further extentions helped. I was getting very frustrated. Then Prof. Hyatt wrote that he was dropping some extentions as modern hardware was so fast that the extentions no longer helped and may even be counter productive. Given my experiance, I tend to agree.

Mike
Hi Mike,

The subject awakened my curiosity and so I ran a quick eng-eng match without the PVS extension. The result was considerable worse than with the default setting (PVS=ON). So it seems the PVS extension is still working.

Ed
I was wondering how you get 2 moves in a row from hashtable. One of the 2 positions would be a fail low node where you normally don't have a hashmove.

Do you store bestmoves in fail low nodes ? Or do you keep the bestmoves on fail low nodes when they previously were fail highs nodes ?

Tony
I think that it is easy to get 2 moves in a row from hashtable in case that you have an exact score and if I understand correctly pvs extensions are about extending moves that have exact score.

If the pv is 1.e4 e5 2.Nf3 Nc6 then in the next search you can extend the position after 1.e4 e5 2.Nf3 Nc6 by one ply.

I did not try it and maybe I do not understand correctly what Ed means by PVS extensions so I think that some chess examples can help to understand the meaning of it.

Uri

Post Reply