Re: [Bug-gnubg] Bearoff dB position, few questions

[Christian Anthon]

I believe that the cubeless data are extracted from the 2-sided db as
well. This results may well be different from that of an evaluation
using the one-sided db. Try moving the 2-sided db out of the way and
repeat the experiment.

Christian.

On Fri, Jun 26, 2009 at 8:52 AM, Misja Alma<address@hidden> wrote:
> Hi All,
>
> Thanks MaX for posting the question on this forum.
>
> So to Christian: You were saying that the cubeful bearoff db is used
> for moneygame but not for matches.
> But the differences that were spotted here were for the cubeless equities?
>
> Cheers,
> Misja
>
> On Thu, Jun 25, 2009 at 9:00 PM, Christian
> Anthon<address@hidden> wrote:
>> The two-sided cubeful bearoff db is exact and used in preference of
>> evalutation, but only for moneygame.
>>
>> Christian.
>>
>> On Fri, Jun 19, 2009 at 3:56 PM, Massimiliano
>> Maini<address@hidden> wrote:
>>>
>>> Hi all,
>>>
>>> on a forum I've found this: same position (in 2-sided bearoff dB)
>>> in money play and match play (3aw-3aw) shows different cubeless
>>> equities. I tried to explain it but I run into some confusion.
>>>
>>> That's money play:
>>>
>>>     GNU Backgammon  Position ID: 6AUAADoDAAAAAA
>>>                     Match ID   : UQkAAAAAAAAA
>>>     +24-23-22-21-20-19------18-17-16-15-14-13-+  O: gnubg
>>>  OO |          O  O  O |   |                  |  0 points
>>>  OO |             O    |   |                  |
>>>  OO |             O    |   |                  |
>>>  OO |             O    |   |                  |
>>>   O |                  |   |                  |
>>>     |                  |BAR|                  |v
>>>   X |                  |   |                  |
>>>  XX |                  |   |                  |
>>>  XX |          X       |   |                  |
>>>  XX |          X     X |   |                  |  On roll
>>>  XX |       X  X     X |   |                  |  0 points
>>>     +-1--2--3--4--5--6-------7--8--9-10-11-12-+  X: MaX (Cube: 2)
>>>
>>> Hint shows this:
>>>
>>> Cube analysis
>>> 2-ply cubeless equity  +0.4971
>>>   0.7485 0.0000 0.0000 - 0.2515 0.0000 0.0000
>>> Cubeful equities:
>>> 1. Double, take         +0.9158
>>> 2. Double, pass         +1.0000  ( +0.0842)
>>> 3. No double            +0.7661  ( -0.1496)
>>> Proper cube action: Redouble, take
>>>
>>> From eval (ctrl+E) I see (uninteresting parts removed):
>>>
>>> Position ID:        6AUAADoDAAAAAA
>>> Match ID:        UQlgAAAAAAAA
>>>
>>> Evaluator:         Bearoff2
>>>
>>>              Player       Opponent
>>> Position          880           912
>>>
>>>         Win     W(g)    W(bg)   L(g)    L(bg)   Equity    Cubeful
>>> static: 0.7485  0.0000  0.0000  0.0000  0.0000   +0.4971   +0.7661
>>>  1 ply: 0.7485  0.0000  0.0000  0.0000  0.0000   +0.4971   +0.7661
>>>  2 ply: 0.7485  0.0000  0.0000  0.0000  0.0000   +0.4971   +0.7661
>>>
>>> Static, 1ply and 2ply figures are identical, which makes me think they all
>>> come from the 2s bearoff dB (eval output is a bit confusing here).
>>>
>>> That's the same for match:
>>>
>>>     GNU Backgammon  Position ID: 6AUAADoDAAAAAA
>>>                     Match ID   : UQlgAAAAAAAA
>>>     +24-23-22-21-20-19------18-17-16-15-14-13-+  O: gnubg
>>>  OO |          O  O  O |   |                  |  0 points
>>>  OO |             O    |   |                  |
>>>  OO |             O    |   |                  |
>>>  OO |             O    |   |                  |
>>>   O |                  |   |                  |
>>>     |                  |BAR|                  |v 3 point match
>>>   X |                  |   |                  |
>>>  XX |                  |   |                  |
>>>  XX |          X       |   |                  |
>>>  XX |          X     X |   |                  |  On roll
>>>  XX |       X  X     X |   |                  |  0 points
>>>     +-1--2--3--4--5--6-------7--8--9-10-11-12-+  X: MaX (Cube: 2)
>>>
>>> Cube analysis
>>> 2-ply cubeless equity  +0.4797 (Money:  +0.4797)
>>>   0.7399 0.0000 0.0000 - 0.2601 0.0000 0.0000
>>> Cubeful equities:
>>> 1. Double, take         +0.9565
>>> 2. Double, pass         +1.0000  ( +0.0435)
>>> 3. No double            +0.7841  ( -0.1724)
>>> Proper cube action: Redouble, take
>>>
>>>         Win     W(g)    W(bg)   L(g)    L(bg)   Equity    Cubeful
>>> static: 0.7485  0.0000  0.0000  0.0000  0.0000   +0.4971   +0.8543
>>>  1 ply: 0.7399  0.0000  0.0000  0.0000  0.0000   +0.4797   +0.8308
>>>  2 ply: 0.7399  0.0000  0.0000  0.0000  0.0000   +0.4797   +0.7841
>>>
>>> The original question was: why the 2-ply cubeless GWC are different
>>> between money and match ?
>>> First answer was: it's using bearoff dB from money and not for match.
>>> Objection was that gnubg could/should use the dB even for match, at
>>> least for the cubeless GWC figures.
>>>
>>> Here I tried to explain that cubefull figures from the dB can only be
>>> used in money play, but what about cubeless ? Are cubeless figures from
>>> the dB used as a base for cubefull eval in match play ?
>>>
>>> Looking at the figures I would say yes: the static cubeless GWC for match
>>> are exactly the ones you have in money. But they diverge at 1 and 2 ply.
>>>
>>> Am I right if I say that doing 2ply eval in match, gnubg needs to compute
>>> a lot of 0ply cubeless evals and it takes them from the dB. The figures
>>> are converted into 0ply cubeful (Janowski formula) and then "backpropagated"
>>> to get 2ply cubeful. 2ply cubeless is computed by inversing the Janowski
>>> formula on 2ply cubeful figures.
>>>
>>> If all the above is true, I do see the objection coming: it's true that what
>>> matter are cubeful figures (and these cannot be taken from the dB in match),
>>> but why gnubg isn't showing the "right" cubeless GWC (the ones from the dB)
>>> in match ?
>>>
>>> Side question: I tried to use bearoffdump. I manage to get the info putting
>>> in the position ID:
>>>
>>> D:\Documents\gnubg>bearoffdump.exe -p 6AUAADoDAAAAAA gnubg_ts0.bd
>>> Bearoff database: gnubg_ts0.bd
>>> Position ID     : 6AUAADoDAAAAAA
>>>
>>> Information about database:
>>>
>>>  * On disk 2-sided bearoff database evaluator
>>>    - generated by GNU Backgammon
>>>    - up to 6 chequers on 6 points (924 positions) per player
>>>    - database includes both cubeful and cubeless equities
>>>    - number of reads: 0
>>>
>>>
>>> Dump of position ID: 6AUAADoDAAAAAA
>>>
>>>              Player       Opponent
>>> Position          880           912
>>>
>>> Cubeless equity               : +0.4971
>>> Owned cube                    : +0.7661
>>> Centered cube                 : +0.7451
>>> Opponent owns cube            : +0.4579
>>>
>>> But I had no success in using the -n option (enter directly the
>>> position indexes, 880 and 921): how is this supposed to work ?
>>>
>>> MaX.
>>> _______________________________________________
>>> Bug-gnubg mailing list
>>> address@hidden
>>> http://lists.gnu.org/mailman/listinfo/bug-gnubg
>>>
>>>
>>
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