[Bug-gnubg] Bug? Pruning On/Pruning Off gives significantly different results at 4ply

[Michael Petch]

Michael Depreli started this thread on BGO.

http://www.bgonline.org/forums/webbbs_config.pl?noframes;read=47533

At first I couldn’t reproduce what he saw but after it was observed that pruning alters the output substantially I came up with this test (Its reproducible on Linux as well, and is not thread related). First what you need to do is load the GUI and change the evaluation parameters to be Supremo for Checker and Word Class for Cube. (This should set things to 2ply cube/2ply checker Pruning ON/cubeful checker evals for cube and checker decisions and a Large filter. Now save the settings.

Re-launch gnubg from the command line (Similar thing happens in the GUI, the CLI is just easier to script. Issue these commands:

set evaluation chequer eval plies 4
set evaluation cubedecision eval plies 4
set evaluation chequer eval prune on
set evaluation cubedecision eval prune on
set gnubgid Position ID: 1a4pwABsd7YAAA Match ID: EYERADAAAAAA
hint
set evaluation chequer eval prune off
set evaluation cubedecision eval prune off
set gnubgid Position ID: 1a4pwABsd7YAAA Match ID: EYERADAAAAAA
hint

My output is attached below. Some curiosities are that with Pruning ON the eval took considerably longer than with it OFF. Most of the pruning off 4ply results seem to be nearly what the 0 ply evals say. I am assuming this is due in part to the “Filter” being used (In this case large) but its interesting it gives wildly differing results and pruning is much slower. I think the question is, is this to be expected, and if not is there a bug?  

Specifically look at “Cubeful 4-ply    9/6 9/5 “ results for both tests below to see where the results end up being considerably different to get an idea on how this was discovered. I think its clear pruning on got this right and pruning off didn’t. Is it the filter settings? And if so is the filter being applied properly with prunign on and off?  

-------
PRUNING ON:

Setting GNUBG id 1a4pwABsd7YAAA:EYERADAAAAAA
(gnubg) hint
    1. Cubeful 4-ply    10/6 5/2                     Eq.:  +0.558
       0.810 0.002 0.000 - 0.190 0.000 0.000
        4-ply cubeful prune
    2. Cubeful 4-ply    10/3                         Eq.:  +0.555 ( -0.003)
       0.809 0.002 0.000 - 0.191 0.000 0.000
        4-ply cubeful prune
    3. Cubeful 4-ply    10/6 4/1                     Eq.:  +0.551 ( -0.007)
       0.807 0.002 0.000 - 0.193 0.000 0.000
        4-ply cubeful prune
    4. Cubeful 4-ply    9/6 9/5                      Eq.:  +0.541 ( -0.018)
       0.800 0.009 0.000 - 0.200 0.002 0.000
        4-ply cubeful prune
    5. Cubeful 4-ply    10/6 9/6                     Eq.:  +0.535 ( -0.023)
       0.798 0.010 0.001 - 0.202 0.004 0.000
        4-ply cubeful prune
    6. Cubeful 4-ply    10/6 8/5                     Eq.:  +0.518 ( -0.040)
       0.791 0.008 0.000 - 0.209 0.002 0.000
        4-ply cubeful prune
    7. Cubeful 2-ply    6/2 5/2                      Eq.:  +0.515 ( -0.043)
       0.789 0.013 0.000 - 0.211 0.003 0.000
        2-ply cubeful prune [world class]
    8. Cubeful 2-ply    6/3 5/1                      Eq.:  +0.511 ( -0.048)
       0.788 0.010 0.000 - 0.212 0.005 0.000
        2-ply cubeful prune [world class]
    9. Cubeful 2-ply    9/2                          Eq.:  +0.510 ( -0.049)
       0.786 0.016 0.001 - 0.214 0.009 0.000
        2-ply cubeful prune [world class]
   10. Cubeful 2-ply    8/5 8/4                      Eq.:  +0.500 ( -0.058)
       0.783 0.011 0.000 - 0.217 0.003 0.000
        2-ply cubeful prune [world class]


PRUNING OFF:

Setting GNUBG id 1a4pwABsd7YAAA:EYERADAAAAAA
(gnubg) hint
    1. Cubeful 4-ply    10/6 4/1                     Eq.:  +0.551
       0.807 0.005 0.000 - 0.193 0.001 0.000
        4-ply cubeful
    2. Cubeful 4-ply    10/6 5/2                     Eq.:  +0.548 ( -0.003)
       0.806 0.004 0.000 - 0.194 0.001 0.000
        4-ply cubeful
    3. Cubeful 4-ply    10/3                         Eq.:  +0.529 ( -0.022)
       0.797 0.004 0.000 - 0.203 0.001 0.000
        4-ply cubeful
    4. Cubeful 4-ply    6/2 5/2                      Eq.:  +0.383 ( -0.167)
       0.732 0.015 0.000 - 0.268 0.005 0.000
        4-ply cubeful
    5. Cubeful 4-ply    10/6 9/6                     Eq.:  +0.376 ( -0.175)
       0.728 0.015 0.000 - 0.272 0.003 0.000
        4-ply cubeful
    6. Cubeful 4-ply    9/6 9/5                      Eq.:  +0.350 ( -0.201)
       0.716 0.020 0.000 - 0.284 0.006 0.000
        4-ply cubeful
    7. Cubeful 2-ply    6/3 5/1                      Eq.:  +0.512 ( -0.039)
       0.789 0.010 0.000 - 0.211 0.005 0.000
        2-ply cubeful
    8. Cubeful 2-ply    10/6 8/5                     Eq.:  +0.511 ( -0.040)
       0.788 0.009 0.000 - 0.212 0.002 0.000
        2-ply cubeful
    9. Cubeful 2-ply    9/2                          Eq.:  +0.509 ( -0.042)
       0.786 0.015 0.001 - 0.214 0.009 0.000
        2-ply cubeful
   10. Cubeful 2-ply    8/5 8/4                      Eq.:  +0.499 ( -0.052)
       0.783 0.010 0.000 - 0.217 0.003 0.000
        2-ply cubeful