Re: [Bug-gnubg] rollout cube decision -- money play: BUG

[Joern Thyssen]

On Mon, Jul 01, 2002 at 09:53:16AM +0200, Robert-Jan Veldhuizen wrote

> Full 2-ply(small) 33%, 1296 trials
> 
> All three results indicate a pretty big drop, and the 2-ply one suggests 
> taking is a huge blunder: 2*(0.6439-0.5)=0.2878.
> 
> But there must be a bug somewhere in these reports; the cubeful equity 
> after taking just can't be right if you look at the win/loss breakdown. 
> Even if opponent never uses the cube, his equity should be better after 
> taking than what's reported; and the cubeful equity should be lower or at 
> best equal to the (cubeless) "equity" in the bottom row; opponent should 
> get some use out of his recube.

Yes, I actually discovered this bug myself this weekend, but I haven't
mamaged to find it yet. I think the critical combination is money game
and variance reduction. If you run the rollout without variance
reduction it seems like you get reasonable results.

> Something else: perhaps it's easier for most people if GNUBG would double 
> the equities of the bottom row in money game rollouts of cube decisions? 
> That would also be more in line with the way match cubes are done (drop 
> when take equity for doubler > +1.000)

I've actually already done this (also in the weekend :-)) Look for a
build dated July 1 or later.

Jørn

-- 
Joern Thyssen, PhD
Vendsysselgade 3, 3., DK-9000 Aalborg, Denmark
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