From: steve uurtamo <[EMAIL PROTECTED]>
> what happens when the opponent deviates from joseki?
> knowing how to punish joseki mistakes can be very, very tricky.
>From my observations at the mogo-vs-pro game, given lots of time and CPU
>cores, Mogo is able to discover how to punish such deviations. In any case, it
>is possible to add such punishing moves to the joseki database -- joseki
>databases such as Kogo often include refutations of bad plays. It is also
>possible to pre-compute possible refutations. Joseki plays, properly used,
>lead to an even result; non-joseki, properly refuted, quickly lead to a
>disparity in the likely score, and hence to the predicted winrate.
> also knowing which joseki to use where is very, very sophisticated. the
> wrong joseki can be worse globally than a non-joseki move.
One hopes that the global search capability of UCT programs will discover which
joseki lead to higher winrates. The proper refutation of a bad choice of joseki
will lead to a lower predicted score and should therefore dominate the winrate.
Joseki should not be treated as mandatory, but as higher-probability branches
of the tree, as a form of move ordering to increase the effectiveness of the
search. When pros play, they are likely to consider joseki first in their much
more selective search trees, and will select something "off the beaten path"
when surrounding circumstances differ. Joseki often provide three or four valid
continuations, each of which is likely to lead to a different direction of play.
Many joseki texts include such circumstances. Play A works only if the ladder
favors Black; play B involves a ko; play C may be chosen if there is a stone
along the side; the pincer at D emphasizes outside influence. These could
provide hints to a smart global search.
Fuseki databases help decide which joseki are most appropriate. I recommend
Kiseido's "A Dictionary of Modern Fuseki / The Korean Style", which seems to be
very thorough and accessible to a kyu-level player such as myself. For non Go
players, Fuseki are tested whole-board opening sequences; Joseki are local
sequences, usually played out the corners - but some, such as the avalanche
joseki, can quickly cover a large section of the board; and some have
dependencies on distant parts of the board, such as ladder-breakers and stones
near one side or the other.
There's a subtle point in handicap joseki -- if you want to win against an
inferior opponent who has a large handicap, you must make deliberate overplays
which would be non-optimal against a strong player.
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