Re: [Bug-gnubg] Some Questions about rollouts.

[Joern Thyssen]

On Fri, Nov 01, 2002 at 04:21:29AM -0500, address@hidden wrote

> Regarding 33% speed. How is this implemented? Could you tell me the maths 
> behind it in not too technical terms please :-)

Normal 2-ply evaluation:

equity=0
Loop over 36 rolls
   find best move for roll
   equity = equity + 1-ply equity for resulting position
End loop

final 2-ply equity = equity/36

The 1-ply equity is defined analagously:

equity=0
Loop over 36 rolls
   find best move for roll
   equity = equity + 0-ply equity for resulting position
End loop

final 1-ply equity = equity/36


Reduced 2-ply evaluation:

equity=0
Loop over 36 rolls
   find best move for roll
   equity = equity + reduced 1-ply equity for resulting position
End loop

final 2-ply equity = equity/36

The reduced 1-ply equity is as:

equity=0
Loop over reduced set of rolls
   find best move for roll
   equity = equity + 0-ply equity for resulting position
End loop

final reduced 1-ply equity = equity/number of rolls

For example, for a 33% reduced 2-ply evaluation the reduced set of rolls
contains 7 rolls whereas a 66% reduced 2-ply evaluation would contain 14
rolls.

Jørn

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