Re: [Bug-gnubg] [Fwd: gnubg search function]

[Joseph Heled]

Last time I used Alpha/Beta pruning was 20 years ago, so my recollection 
is hazy. Still, a/b is for min/max trees. In BG, the node value is the 
*arithmetical weighted average* of it's children, not a min/max. this is 
what makes BG intractable to brute force.

-Joseph

Thomas Hauk wrote:
> On Fri, 28 Mar 2003, Joseph Heled wrote:
>
> > I might be missing something, but I can't see how this applies to 
> > Backgammon. Looking at some of the continuations (i.e. subset of 
> > possible rolls) can't give you a bound on outcome of other rolls.
>
>
> You wanted a brief explanation. 8)  Unless you are familiar with alphabeta 
> search, it will be difficult to explain the concept. Try Googling around 
> for a decent alphabeta Web page. Something like 
> http://www.cs.mcgill.ca/~cs251/OldCourses/1997/topic11/
>
> You can't get a bound for the outcome for any rolls until you have 
> searched to the bottom of the left-most branch of the game tree. You then 
> can begin to obtain cutoffs. See Figure 4 on that Web page.
>
> --Tom