Re: [Bug-gnubg] Why is odd ply equity always lower?

[Nis]

--On 19 June 2003 07:20 +0000 Joern Thyssen <address@hidden> wrote:

> On Wed, Jun 18, 2003 at 10:24:38PM +0200, Nis wrote
> [snip]
> > Only relevant for cube decisions?
> >
> > The wrong estimations of equity is mainly a problem of absolute
> > equities.  As Joseph has pointed out, chequerplay relies almost solely
> > on the relative  equities of positions.
> >
> > Thus a fix should only "need" to be applied for cube decisions (and
> > cubeful  chequerplay? Someone help me here)
> >
> > So we might want to start using reduced evaluation settings for cube
> > decisions
>
> Haven't seen your patch yet, I think it may be much easier if we add an
> option to evalcontext that enables this. The evaluation routines doesn't
> really know if it's evaluating a cube decision or chequer play decision.

My idea was to set this up in the predefined evaluation settings.

TODO: allow named configurations to be set up by command:

set evaluiation HUGE

> BTW, I'd be happy to see your patch! If it's not too large you can
> probably post it on the list.

I've attached it. Please note that the combination of your "deterministic 
reduction" is that 1-ply reduction is always using the first of the roll 
lists. But reduced 1-ply is probably a bad idea anyway. The option is 
there, however - I implemented a fix.

My first unscientific tests show a much higher correlation between 1- 2- 
and 3-ply when using reduced evaluations. For instance, after an opening 
5-4 played 24/20, 13/8, this is the eval on 100%

       Win     W(g)    W(bg)   L(g)    L(bg)   Equity  (cubeful)
static: 0.484   0.125   0.003   0.136   0.006   (-0.046  (-0.064))
1 ply: 0.501   0.134   0.005   0.136   0.005   (-0.001  (-0.001))
2 ply: 0.481   0.128   0.004   0.141   0.007   (-0.053  (-0.073))
3 ply: 0.499   0.133   0.004   0.136   0.005   (-0.006  (-0.008))

and this is the eval on 50%

       Win     W(g)    W(bg)   L(g)    L(bg)   Equity  (cubeful)
static: 0.484   0.125   0.003   0.136   0.006   (-0.046  (-0.064))
1 ply: 0.488   0.123   0.004   0.143   0.006   (-0.046  (-0.062))
2 ply: 0.492   0.131   0.004   0.138   0.006   (-0.024  (-0.032))
3 ply: 0.491   0.130   0.004   0.138   0.006   (-0.029  (-0.040))

--
Nis Jorgensen
Greenpeace
Amsterdam

eval.patch
Description: Text document