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Orthodox Play
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    Keywords: EndGame

Orthodox is a term in combinatorial game theory, coined by Elwyn Berlekamp. Informally, orthodox play is normally correct play, making the largest play first. In a real game, of course, the largest play is not always the best play. (See tedomari.)

In figuring out the size of plays you can suppose that there is an ideal environment of other plays with closely spaced sizes such that the correct play is the largest play and that, if there is a choice between two local plays of different sizes, there is a play in the environment that has a size in between them. If there is no such play, the correct local play, if any, may depend on the size of the largest play in the environment (the ambient temperature).

Since the normally correct play is not always correct, even locally, we can't just call it correct. But we need a word to describe it, and so we call it orthodox.

-- Bill Spight


See a related page at greedy go.


BobMcGuigan The description above doesn't seem to mesh with the way some Japanese pros describe their style as "orthodox". In this case I imagine it might mean that when there are different moves, all worth the same, that the pro in question would tend to choose the "normal" one. But what does "normal" mean? Maybe this means "in keeping with what most Japanese pros would play"? It might also refer to some sort of familiar, predictable moves where the consequences are fairly familiar in Japanese professional experience. So I guess players with an "orthodox" style would not be innovating new moves or patterns.


Bill: Indeed, it does not mesh with vernacular senses of orthodox. It is a technical CGT term, coined by Elwyn Berlekamp. I chose to give an informal definition instead of getting too technical.


Charles Matthews I have tended to describe the use of orthodox Bob refers to as 'the Nihon Ki-in style'; not because all Nihon Ki-in players adhere to it (that tends to be least true of some of the strongest), but because I have the impression that there is a corporate style. We're really too weak to discuss such matters in an informed way, but there's honte on one side and pace on the other, and orthodox play is somewhere in between, a little thicker and much more alert than amateur play. I believe Kato Masao would be considered an orthodox player, for example, now that he puts emphasis on the endgame.


HolIgor: When the orthodox play is defined as the largest (best) play locally, I don't see how it is different from tesuji. Perhaps, the term tesuji can be suggested to Professor Berlekamp. The term orthodox move is not intuitively clear, and can be confusing while tesuji is totally obscure which can be much better in such situations. The go players would understand while for other games this could be a new fresh term.


Bill: The largest play may not require any tactical skill. There are fewer tesuji than orthodox plays. And I suppose that there are cases where tesuji is not orthodox.
As for orthodox not being intuitively clear, that is so. The intuitive word is correct. Unfortunately, correct is not correct.




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This is a copy of the living page "Orthodox Play" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.