Houdini and Gaviota Tablebases

[pawnslinger]

I am using Chessbase as my GUI to run Houdini, and I have downloaded the GTB files for 3-4-5 positions. I have passed the path where the files are located to Houdini, and left other parameters unchanged. I have a krpkr position that is a dead draw (according to online 6 piece tablebase run by ChessOK (I think)). But Houdini acts like no TB are loaded, it just goes about its search in the normal manner, but it shows "tb=20" now, as a part of the search display. It doesn't do that without the GTB loaded.

What does this mean? I was expecting the result of the GTB lookup to be displayed. Do I need a different GUI? Are my copies of the tablebase files bad? Does "tb=20" mean "draw in 20 ply"?

[alpha123]

What do you expect it to display?

tb=20 means the engine searched 20 positions which were in the tablebases.

Peter

[michiguel]

I am using Chessbase as my GUI to run Houdini, and I have downloaded the GTB files for 3-4-5 positions. I have passed the path where the files are located to Houdini, and left other parameters unchanged. I have a krpkr position that is a dead draw (according to online 6 piece tablebase run by ChessOK (I think)). But Houdini acts like no TB are loaded, it just goes about its search in the normal manner, but it shows "tb=20" now, as a part of the search display. It doesn't do that without the GTB loaded.

What does this mean? I was expecting the result of the GTB lookup to be displayed. Do I need a different GUI? Are my copies of the tablebase files bad? Does "tb=20" mean "draw in 20 ply"?

You copies may be good. In fact, there are ways to verify them.
http://sites.google.com/site/gaviotache ... b-checking

But Houdini's author has mentioned that H. wants to keep playing when it is a dead draw but there is material advantage. To do that, H. may need to ignore the TBs at the root. There was a thread about it.

Miguel

[pawnslinger]

I was unsure what to expect. But since I am used to using online tablebases, I was expecting something like they show, the result followed by the key move or perhaps pv. I have seen displays from Winboard using a tablebase, and it shows a list of key moves with the result for each and the number of plies needed to reach the result.

I guess I am just confused, and wonder if I have wasted my time downloading and installing these GTB. I am not sure what the benefit is... the pv that Houdini shows doesn't match the pv shown by the online tablebase (although I checked and the pv that Houdini suggests is a draw too). But Houdini shows a 1.81 eval in its search display. That could mislead some (it sure confuses me).

[Houdini]

I have a krpkr position that is a dead draw (according to online 6 piece tablebase run by ChessOK (I think)). But Houdini acts like no TB are loaded, it just goes about its search in the normal manner, but it shows "tb=20" now, as a part of the search display. It doesn't do that without the GTB loaded.

What does this mean? I was expecting the result of the GTB lookup to be displayed. Do I need a different GUI? Are my copies of the tablebase files bad? Does "tb=20" mean "draw in 20 ply"?

The EGTB tells Houdini that it's a draw.

If Houdini is the stronger side, it notices it's a full pawn ahead and decides to play for a win. Who knows, the opponent might not have access to table bases!
Houdini selects all the moves that draw according to the EGTB (that's the 20 table base hits you're seeing), and will choose the best attempt at winning by performing an analysis without EGTB.

If Houdini is the weaker side, it will simply pick any move that draws according to the EGTB and stop the analysis immediately.

This behavior can be confusing, I agree.

Robert

[michiguel]

I have a krpkr position that is a dead draw (according to online 6 piece tablebase run by ChessOK (I think)). But Houdini acts like no TB are loaded, it just goes about its search in the normal manner, but it shows "tb=20" now, as a part of the search display. It doesn't do that without the GTB loaded.

What does this mean? I was expecting the result of the GTB lookup to be displayed. Do I need a different GUI? Are my copies of the tablebase files bad? Does "tb=20" mean "draw in 20 ply"?

The EGTB tells Houdini that it's a draw.

If Houdini is the stronger side, it notices it's a full pawn ahead and decides to play for a win. Who knows, the opponent might not have access to table bases!
Houdini selects all the moves that draw according to the EGTB (that's the 20 table base hits you're seeing), and will choose the best attempt at winning by performing an analysis without EGTB.

If Houdini is the weaker side, it will simply pick any move that draws according to the EGTB and stop the analysis immediately.

This behavior can be confusing, I agree.

Robert

You may want to put this as an option in a UCI parameter because it looks like many people get confused. Bob H. had a name for what you do but I do not remember what it is. I am doing something different but the concept is similar. I called it "pouncing mode" and the user can choose to click it on or off.

Miguel

[Houdini]

You may want to put this as an option in a UCI parameter because it looks like many people get confused. Bob H. had a name for what you do but I do not remember what it is. I am doing something different but the concept is similar. I called it "pouncing mode" and the user can choose to click it on or off.

Miguel

Indeed, I could make this behavior optional (enabled by default).
However the user would need to have an understanding of the behavior of the program before being able to decide to disable it, so I'm not convinced it makes a lot of difference.

Robert

[pawnslinger]

Robert said:

"The EGTB tells Houdini that it's a draw.

If Houdini is the stronger side, it notices it's a full pawn ahead and decides to play for a win. Who knows, the opponent might not have access to table bases!
Houdini selects all the moves that draw according to the EGTB (that's the 20 table base hits you're seeing), and will choose the best attempt at winning by performing an analysis without EGTB.

If Houdini is the weaker side, it will simply pick any move that draws according to the EGTB and stop the analysis immediately.

This behavior can be confusing, I agree.

Robert"

Hi Robert:

I guess the problem here is that Houdini is not actually playing, it is a "Kibitzer" to help me analyze an ICCF game (where engines and tablebaes are okay to use). I use a variety of tools, and spend a lot of time, tryng to figure out a position. The process I use involves multiple engines and GUI's. No single one gives me all of the information I want. It is a good thing to have Houdini work the way it does, I want it to do what it does, I just didn't understand the information it displayed.

I am somewhat new to using tablebases, and this is my very first use of one installed on my local computer. I noticed that it did speed up Houdini quite a bit, reaching a ply depth of 40 very very quickly.

To get more information from the tablebase, I have installed Winboard with Gaviota (since my first message in this thread), and using the "Book" menu option, it gives me the read-out from the GTB. I don't see how to get that from Chessbase. When I installed Winboard, it came also with Houdini, will Houdini provide a list of the GTB output like Gaviota does with the "Book" option??

[Arpad Rusz]

You may want to put this as an option in a UCI parameter because it looks like many people get confused...

Miguel

Indeed, I could make this behavior optional (enabled by default).

Robert

Houdini's clever TB behavior is good for playing a game but not for analysis.

[BubbaTough]

Perhaps it should avoid this behavior when in analysis mode (time = inf).

-sam