[Computer-go] Semeais

[Kahn Jonas]

On Fri, 14 Jan 2011, David Fotland wrote:

> Many Faces does something like this, and it does not work well.  Many Faces
> includes a static semeai solver with local search, and this is applied in
> the tree.  If anyone has many faces you can set up a semeai and ask for
> group status.  This shows you the result of the static life/death/strength
> analysis, and you can see the kind of semeai it will leave for the playouts.
>
> The problem comes when the tree finds the semeai, and the correct move is
> made in the tree to resolve the semeai.  At the exit from the tree, any
> semeai on the board has been resolved (in that one side will win by
> typically one move).  The tree won't waste extra moves in the semeai, so at
> tree exit, the winning side is one move ahead.
>
> Then the playout has no clue about the semeai, and lets the losing side win
> perhaps 40% of the time.

As I understand it, the idea was that during the playout, if any move is made 
by the losing side within the semeai, it triggers an automatic answer to keep
the semeai solved in the same way; and the winning side is forbidden to
play in the semeai otherwise.
(at least because of the semeai, a move chosen by proximity heuristics
or patterns not from the semeai would be OK, I guess.)

> Semeai knowledge is required in the playout.  The tree must leave resolved
> semeai positions on the board which the playouts can't understand,
> introducing a large bias.

Sure.
That was also why it was suggested just to bluntly finish the semeai
before the playout, but maybe that bias is also too big.

Jonas