Re: [Bug-gnubg] Question about higher plies

[Øystein Johansen]

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Joachim Matussek wrote:

| Hello,
|
| I was musing a little bit and following question arose.
|
| E.g. you are calculating a 2-ply. At 0-ply it is a contact position,
| but depending on the move chosen it may become a race at 2-ply.
| Do you switch neural nets within this evaluation?

I'll try to explain:

The 2-ply evaluation is the aritmetic mean value of a 0-ply the position
after the assumed best move after all 1296 dice combination. If you
imadgine this as a tree with 1296 leaves, it is therefor the average of
the evaluation of all these 1296 leaves. Each of the 1296 positions are
evaluated with its proper neural net.

However, of course it's only 441 different position evaluated, since
there is only 21 distinct dice rolls.

Now comes some questions from me as well:
The evaluation function is coded with recursion. I therefore assume
EvaluatePosition must be calling ClassifyPosition for each time it's
called. Can we improve the speed of the evaluation if the position type
was given as a argument to the evaluation function and determined before
the call? Of course, implementing this means we must have a function
before calling EvaluatePosition which finds whenever a position class
change is possible of not. (I have not thought about the function yet,
I'm just thinking while I typing)

pseudo code:

if(position class can possibly change over n-ply):
~    Evaluate the position as usual.
else:
~    Evaluate position with a function that take position class as arg.

Will this improve the evaluation, assuming we can find a function to
determining if the position class can change? Maybe not! The
ClassifyPosition function isn't the most time consuming function, is it?

- -Øystein

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