which setting is better for analysis/playing ? 3-ply OR 2-ply?

[LENNA]

hello everybody. i'm lenna piruz. a backgammon player like you . i play backgammon at netgammon server and you
can find me there . my ID is L_Enna.
last night i had a struggle with my frined (her netgammon ID is : Shivuli657) about playing strength of GNU.
she told me 2-ply(world class) is better and stronger at playing..she surprized me !
because i think 3-ply(Grandmaster) is extremely strong. and i think if you run a 21point match between world-class and GrandMaster
and export the file to Extremegammon and analyse it you will see the Pr of grandmaster is less than the Pr of World-class..
i just want you to finish this struggle and tell us which one is better..
i have analysed many games and grandmaster had better snowieErrorRate..any result of Grandmaster was supernatural(at cube-checkerplay)
i'm waiting to your comments..thank you very much. bye

[vegasvic]

3 ply is much better the cube action on 2 ply can be off .

Lenna also come visit us at Tigergammon.com , it will tell you how to log on .

Good luck with your Games .

[Zorba]

For older versions of GNUbg (upto v0.90, mid 2013), 3-ply checkerplay was better than 2-ply, but 3-ply cube action was actually quite a bit worse than 2-ply. Overall, the 3-ply cube action was bad enough that 3-ply could be playing worse than 2-ply overall.

The newer versions of GNUbg (v0.91 and v1.0 and up) play better in general and have solved much of this "bad odd-ply cube action" problem. Now 3-ply cube action is just a little bit better than 2-ply cube action and 3-ply checker play is still clearly better, so overall 3-ply is clearly better than 2-ply.

Some figures from a benchmark, showing the errors made:


Bot Description                     Chequer Errors     Cube Errors     All Errors
--------------------------------------------------------------------------------------------------------------------------------------------------------------
GNUBG v0.91 4-ply                     9.1071(1138)       3.4287( 116)     12.5358(1254)
GNUBG v0.91 3-ply Grandmaster        12.8651(1391)       3.9101( 134)     16.7752(1525)
GNUBG v0.91 2-ply WorldClass         16.6188(1559)       4.3317( 135)     20.9505(1694)

GNUBG v0.90 4-ply                    16.0467(1414)        8.8001( 195)     24.8468(1609)
GNUBG v0.90 2-ply WorldClass         25.9465(1814)       10.3792( 212)     36.3257(2026)
GNUBG v0.90 3-ply Grandmaster        22.0227(1794)       17.8564( 269)     39.8791(2063)
--------------------------------------------------------------------------------------------------------------------------------------------------------------

Bad 3-ply cube action, and resulting higher error total of the older v0.90 version in red


So, for the old gnubg, 2-ply was a better setting than 3-ply, or one could use 3-ply checker with 2-ply cube to get the best of both worlds.

The new gnubg is simple: 4-ply is better than 3-ply is better than 2-ply, for cube, checker and overall.

[dorbel]

Thank you Zorba, that seems clear and as it should be. One does wonder though why somebody with access to XG would bother with the inferior Gnu or greatly inferior Snowie.

[vegasvic]

Some of us run Mac OS 10. plus  dorbel and XG does not work .
besides seriously do you think if a human can play well as gnu 3 play he or she needs to worry and go to XG ?

I know its much better program i have heard from many pro's on gridgammon , but GNU is free )

[KDP]

i have to go w/ vic on this one.  i have both but ultimately i like my macbook better than i like XG.  besides im not at the point in my backgammon life where i need to or care about finding a move that is 2/100 of a percent better than the other.

[dorbel]

Yes, it isn't really a question of the analysis on XG being stronger, although it is, but more that the interface and the way in which past data is stored and presented that is so very much better. Of course Gnu is free and will run on a Mac, but there is no doubt which bot is superior. I just wondered why the original poster who obviously had access to XG, was wondering about the best way to use Gnu.

[ah_clem]

One does wonder though why somebody with access to XG would bother with the inferior Gnu or greatly inferior Snowie.

A couple spring to mind:

• I only ponied up for two XG licenses and I have more than 2 computers.  
• I like playing against gnu better than XG.  Not sure why, I just do (and it's not due the the playing strength).
• A second opinion can be helpful sometimes.  
• At my level of play, the differences between gnu and xg are miniscule compared to my errors.  
• There are some aspects of the UI where I like gnu more, for instance showing the moves in two columns instead of one.  
• I think it's good for the health of the backgammon community to have more than one bot.  If Xavier gets bored or moves on to other things it's good to have others working on bot development.

That said, I switched about two years ago after realizing that gnu 2-ply analysis  was steering me in the wrong direction at times, and I was learning some incorrect ideas - for instance, over valuing bar point holding games.  I really like the PR number as a good proxy for how well I played, and the tracking of matches is much much easier than in gnu.

But I still use gnu for some things and strongly support the gnu team and thank them for doing a great job.

Snowie?  Yeah, I don't get why anyone would still use that today.