# Semantic questions [#883]

213.73.67.45: Semantic questions (2007-02-21 11:28) [#3096]

In "odd cycle", is "of plays" = "of board plays"? In "ko", is "of plays" = "of board plays"? In "ko", what exactly shall be the meaning of "contain an odd cycle"? Please spell out this in a much more precise wording of the text. In "ko play", is "play" = "board play"? In "hot stone", when has "current sequence" started? At first, I am afraid that "unless that capture is not a ko play" might be ambiguous, but I need to study it in greater detail. The "odd cycle rule": "An odd cycle may be played once only." What does this mean? Does it apply to each odd cycle separately? May never any second cycle occur during the game, regardless of whether they might be about the same thing? --RobertJasiek

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Bill: Re: Semantic questions (2007-02-21 19:40) [#3099]

In "odd cycle", is "of plays" = "of board plays"? In "ko", is "of plays" = "of board plays"?

The phrase, "of plays" does not appear in either definition. Both ko and odd cycle are defined in terms of board plays.

In "ko", what exactly shall be the meaning of "contain an odd cycle"? Please spell out this in a much more precise wording of the text.

Let me give an example. I shall represent board plays by small boldface letters. Suppose that the sequence, abc, is an odd cycle. Suppose also that the sequence, def, is an odd cycle that is independent of abc. Then the sequence, abcdef, is an even cycle that contains two odd cycles. The sequence, adebcf, does not contain an odd cycle.

Hmmmm. I expect that it should. Else the existence of two odd sequences could create a fighting ko. I have amended the rules accordingly. Many thanks. :-)

In "ko play", is "play" = "board play"?

Ko is defined in terms of board plays, so all ko plays are board plays.

In "hot stone", when has "current sequence" started?

The current sequence starts with the first ko play in the sequence.

At first, I am afraid that "unless that capture is not a ko play" might be ambiguous, but I need to study it in greater detail.

Let me give an example.

Triple ko stones

Suppose that after Black plays in the next diagram.

Triple ko stones

is a hot stone because there is a ko cycle that continues with Wa - Bb. However, White is allowed to capture with Wb.

If Black objects to the capture, it is up to Black to show the ko sequence starting with the capture.

The "odd cycle rule": "An odd cycle may be played once only." What does this mean? Does it apply to each odd cycle separately? May never any second cycle occur during the game, regardless of whether they might be about the same thing?

Odd cycles are disturbing kos for Ing. The odd cycle rule is a variant of Ing's rule allowing a disturbing ko to be played once only, but in different terms, since I do not appeal to the fighting ko/disturbing ko distinction.