Hello Dmitry,
Your code says that the value is backed up by sum and negation (line 26,
>> value := -value). But I don't see any negative values in your sample
tree,
>> or values greater than one. How do you actually back up values to the
>> root?
>Sorry, it is value := 1-value. Thank you for pointing out the mistake.
I am confused about value. What is it actually storing? I thought
node[i].value stores the number of wins (for Black) for node i. Then why
some of the values in Figure 1 not integer?
If line 26 is now value := 1-value, then should some of the other lines
also change? For example should line 7 be updateValue(node,
1-node[i].value), and line 16 be else v[i]:= (1-node.childNode
[i].value)/node.childNode[i].nb+sqrt(...)?
You're right there were some confusion :-).
In fact it is very simple. The "-" is here because it is negamax and not
minimax, so that you can always take the max of the value (but the value is
negated every 2 levels). The value stored then corresponds to the value of
"the player to play" in the node.
It seems that node[i].value indeed keeps the number of wins for the player
to play in node i. the "1-" does not exist.
In Figure 1, it is an example of UCT in general case, where the reward is
not always in [0,1]. And the values displayed in the nodes are the averages.
So that explains the non integers and the values not in [0,1].
Can you also update all the changes in your report? Thank you.
I'll try to find sometime to do that. Can't tell it will be soon though.
Regards,
Sylvain
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