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

[Misja Alma]

I tried to move the 2-sided db out of the way, like you said.
Just to confirm that I did it correctly:
I went to the gnubg folder on my (unbuntu) pc and did 'mv gnubg_ts0.bd
gnubg_ts0.bd_bak'
Then I restarted gnubg and entered the position, but the cubeless
winning chances are still different for money game than for a 3 pt
match.

Misja

On Fri, Jun 26, 2009 at 8:57 AM, Christian
Anthon<address@hidden> wrote:
> 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.
>>>> _______________________________________________
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>>>>
>>>>
>>>
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>