Komaster / Discussion

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Komaster Discussion:


I'm confused. Is the property of someone being Komaster internal to the ko, or is it a matter of external ko threats? It seems to me that in the first diagram Black does have to ignore White's ko threat with 7. Does this mean that Black is komaster because White has no ko threats (or none big enough)?

--jsha


Bill: From an analytical point of view, one beauty of the komaster concept is that you do not have to work out exactly what it takes for a player to become komaster. The komaster has just enough ko threats to win the ko without having to ignore an opposing threat. In practice, of course, there is often a trade-off between winning the ko and allowing the opponent to complete a threat. This is called the ko exchange.

In the first diagram, if Black is komaster White has no ko threat to play at move 7. If White plays a small ko threat that Black has to ignore, Black is not komaster.


Jan: Hey Bill, when are you going to write Breakthrough to Komaster? I'm sure Ritchie Press will want to publish it?


It would be nice if someone could write down the answer to the question "How do I know who is komaster?". If I knew how to determine it I might understand it :). The above discusion really doesn't seem to clarify anything for me. It sounds an awful lot like the komaster is simply the person who has enough excess ko threats to win. There is also a lot of asigning points in the above, which seems difficult if not impossible without knowing the position on the rest of the board.

Bill: In the precise technical meaning of the term, for a player to have just exactly enough threats that are large enough so that she is komaster is against the odds. Usually one player or the other has more than enough large enough threats to win the ko without having to ignore an opposing threat, or neither player is komaster.

Simple examples can be given, however. The simplest is that of a simple one-step ko where neither player has a ko threat. The player to take the ko is komaster.

Charles It's a modelling term, anyway. The better question is 'how can I tell whether the results from the model apply to my game?'

Bill: The beauty of the komaster idea, IMO, is that for the first time it gave us a way to calculate the value of single kos in a manner similar to the way we calculate the value of other plays. For that, it's vagueness in terms of what conditions need to be met on the the go board for a player to be the komaster for any specific ko fight is a virtue, just as the vagueness for calculating the value of non-ko plays about other plays on the board is a virtue.

For non-ko plays we have a good idea of the conditions on other plays that have to be met so that we can have confidence in the theoretical results. I. e., that the largest play is the best play. Furthermore, we know that these conditions are typically met, so that playing the largest play is usually correct.

For placid kos, which have the same value regardless of who is komaster, we can be relatively confident. However, komaster calculations do not provide absolute limits, so we cannot be as confident about any ko as about non-kos.

For hyperactive positions, such as approach kos, mannen kos, and positions which threaten fights for large placid kos, the story is different. Being able to calculate their value gives some guidance, where before there was none, but little is known in general about conditions for komaster, so our level of confidence is much lower.

There are other ways, which I pioneered, of theorizing about such positions by analyzing kos and threats together in what I term a ko ensemble. However, that theory is so complex that it is not yet of any real practical use.


But is there some objective definition of a 'ko threat'? Isn't 'ko threat' just a relative term? Doesn't almost every reasonable move threaten some follow-up? So how is it possible to connect a ko without ignoring a threat? And doesn't this make 'komaster' quite a vague term?

-- JuhoP

Bill: I do not believe that there is a comprehensive formal definition of a ko threat. There are definitions for specific types of ko threats. Like sente, ko threat is a fuzzy term.

Yes, most reasonable moves have follow-ups. But that does not mean that the follow-up is a threat.

E. g., suppose that we have the following plays, as well as a simple ko:

                    A          B
                   / \        / \
                  C   0      6   0
                 / \
               10   6

If Black plays from A to C as a ko threat, White will surely ignore it. Either she will win the ko or respond in B.

Komaster is not a vague term. It is precise. However, as Charles points out, it belongs to a model. That model may apply to the current situation to varying degrees, or not at all. Maybe nobody is komaster.

Let me add that the explanation I gave of komaster is not its formal definition. For that, see [ext] http://www.msri.org/publications/books/Book29/files/ber.pdf. I tried to explain the term for the average go player. :-)


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