Re: [Bug-gnubg] Question about the Hint Window Evals

[Pablo Sangster]

Øystein O Johansen wrote:
> > Firstly my apologies for remaining anonymous.
> > My name is Pablo Sangster
> > Thanks you for your quick response.
>
> Hi, Pablo! Nice to meet you!
>
> > > You can of course press the "..." button and turn off the pruning
> > > neural nets for the evaluations done with the "Eval" button. If I
> > > coded the cache key calculation correctly to take the prune net
> > > setting into account, the evaluation will be redone without use of
> > > the pruning nets.
> >
> > Yes thank you for this tip. It didn't occur to me.
>
> This was the final argument for setting pruning nets default on.
>
> > Yes I fully understand how the pruning neural nets work.
>
> Good!
>
> > However my speciality is backgames and I am finding that there
> > are enough differences between the prune and full nets to matter.
>
> Yes, you're right. In some backgame positions the pruning neural nets
> will possibly do some bad pruning. However it is not sure the normal
> nets will do the right move either. ;-)

I wanted to check what move was chosen at it's optimum setting (at 2-ply) 
and yes
you're right in that where it doesn't understand the position well, it may 
not find the "best" play anyway.
> If there is a position type where I believe that turning the pruning
> nets off can give some improvments it must be in backgames.
>
> > BTW I think GNU could do with some more training in developing
> > backgames...
>
> I've started to look at Josephs training code and tools and I do
> some small test with differnt nets. Howevere I belive it's really
> hard to improve the current nets much more as they are without
> splitting further or introducing other inputs. (However I don't
> believe introducing other inputs is the best strategy either.)
>
> A long long long time a go (in this galaxy), Joseph tried to make
> a net specially for backgames and prime position. However, this net
> wasn't a success and Joseph abandoned the net. This must have been
> at least 5 years ago. It must have been in the sourceforge period
> of the project.

Joseph and the Gnubg team have done  tremendous work in bringing the
program up to its current strength. I always compare it's moves to Snowie 4 
(which
has specifically been trained for backgames) and I believe and other experts 
that I have spoken to
agree that Snowie's moves appear "more correct".
So I presume Gnubg could be improved in this part of its game but as you 
pointed out it isn't
that simple without affecting the nets overall.
> What 'part' of the backgame do you find flaws? In developing a
> backgame? I really find the positions where gnubg is developing a
> backgame really strong. I see it make most mistakes after it hits.
> It dosn't understand how contain the checker properly. Specially
> if it's hitting late.

It will commit to a back game too early by playing loose kamikaze plays 
where it
still has a very flexible position which could easily be won going forwards.

I believe Gnubg could also be slightly improved in "holding games" and " 1 
checker back games".
I think it generally over values the holder.

Pablo

> -Øystein
>
>
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