[Welcome to Sensei's Library!]

StartingPoints
ReferenceSection
About


Aliases (info)
Orthodox

Paths
CGTPath

Referenced by
Tedomari
AssumptionsOfYose...
GoTheoryAndCGTDis...
GreedyGo
ThermographyDiscu...
CountingSolution01
HuBimSu
LosingSente
SnapbackProblem22...
OG2W150TheScore
BQM42
DeiriCounting

 

Orthodox Play
Path: CGTPath   · Prev: Cooling   · Next: Reversal
  Difficulty: Advanced   Keywords: EndGame, Theory

Orthodox is a term in combinatorial game theory, coined by Elwyn Berlekamp. Informally, orthodox play is locally optimal play at a given ambient temperature.

When the term is used without reference to temperature, the ambient temperature is assumed to be just cool enough so that each player has an orthodox play instead of passing or playing elsewhere.

(That is the way I, Bill Spight, have usually used the term here on SL.)

Now, the rest of the board may be such that orthodox play is not correct. See, for instance, tedomari. Since the normally correct play is not always correct, 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.

Discussion

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[1] 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.


Sebastian: Just an idea: How about calling it "orderly"? This would express that moves are done in order of decreasing size.

Bill: A game may be the sum, or combination, of more than one game (hence, ''combinatorial'' game theory). In such a case orthodox play may not be in order of decreasing size. Perhaps I was too informal in the first paragraph (since revised :-)). Orthodox play depends upon the thermograph, which I did not mention, as we really do not have a good exposition of thermography here. However, even with a combination of games, if the ambient temperature is high enough, orthodox play is the largest play.


[1] Bill: In an earlier version of this page I talked about orthodox play as being the largest local play. You can see how that ties into the notion of being optimal local play when the ambient temperature is just low enough to make a local play optimal. However, that formulation seemed to cause some confusion, which you can see in the ensuing discussion. I hope that my revision is clearer.



Path: CGTPath   · Prev: Cooling   · Next: Reversal
This is a copy of the living page "Orthodox Play" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.