[computer-go] On question about Libego110

[Łukasz Lew]

The code of any version is easy to get:
http://www.mimuw.edu.pl/~lew/hg/libego/?tags

The file you are talking about is here:
http://www.mimuw.edu.pl/~lew/hg/libego/?file/dfcd0a6db96e/uct.cpp


If you take a look at line 151 you see: (bias should be renamed to
number_of_visits)

    explore_coeff  = log (bias) * explore_rate;

where bias is equivalent to this->bias i.e. number of visits in current node.
2 lines lower is a loop over all children where we compute:

   float child_urgency = child->ucb <pl> (explore_coeff);

where the body of ucb is:

    return
        (pl == player::black ? value : -value) +
        sqrt (explore_coeff / bias);

and "bias" variable refers to the child's bias.

If you have any more questions, just ask.
Łukasz

On Jan 9, 2008 7:49 PM,  <compgo123 at aol.com> wrote:
> I'm looking at the code of Libgo110. I have a question. In the file uct.cpp
> and the definition of class note_t, the explore_coeff is calculated from
> log(node->bias). But in the paper 'Modification of UCT with Patterns in
> Monte-Carlo Go' table 1 line 10 -17, the explore_coeff is calculated from
> log(nb), where nb is the summation of node->bias for all the child nodes.
> Whyis the difference? Or did I read the code wrong?
>
>  Thanks for any explanation.
>
>  DL
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