[Computer-go] issues on 19x19
dshawul at gmail.com
Wed Apr 27 08:23:41 PDT 2011
I am having problems making my engine play a decent game on 19x19 board.
Some KGS games
exposed the following problems.
1) Ladder problem. It often mis-evaluates ladders despite my best efforts to
in the playouts. So I resorted to doing qsearch at the root to weed out
loose tactically, and make winning moves immediately. That helped but
sometimes the qsearch explodes and engine looses on time.
I tried putting a limit to the depth of qsearch but it still runs into
problems. Using a small depth limit may
help in 9x9 but on 19x19, atleast 40 plies is required to detect one ladder
along the diagonal... so what to do ?
2) My second problem concerns use of progressive widening/unpruning which
looks like a must to have on 19x19.
The problem I have is with the move ordering... If I tell it to moves on
the 3rd line from the edge are good ones,
it continually puts its stones on that line (hence forming a square), while
the opponent controls the centre and also
cuts some parts of the 3rd line.
Then I used fillboard to try and fix this issue, but the engine once again
tends to prefer these moves and put stones
all over the board. Which is when I realized it is impossible to fix it with
static move ordering.
Should I use something dynamic like RAVE to order the moves? That will be
inconvinient because I order the nodes
only during first allocation.
Also the default progressive unpruning formula seems to select too few moves
for consideration, so I had to add 20 additional moves
to make it work for my engine.
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