Values of moves

[Calvin Clark]

Warning: Mathlish

In fabulously lazy fashion (and therefore potentially incorrect) I'll use a tool to create the thermographs for me.

Second position first:

If it looks like a sente, quacks like a sente, it's a sente:

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The first position is more complex. There is a small double gote region when the temperature is between 5/2 (2.5) and 11/4 (2.75).

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[Bill Spight]

A is White sente if and only if (b-c)/2 > a-b.
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Given position P and players A and B:
Position P is sente for player A if player B's reply to player A's play from position P gains more than player B's play from position P.

That's the correct version of O Meien's definition.

What slightly wrong definition does O give?

O Meien defines sente in terms of what the Go Player's Almanac calls privilege, and John Fairbairn translates as right. The idea is that a play is (local) sente if one player has the right to make it. Here is O's definition of right.

If we were to give a definition of “right” here, it would be: if the next move is bigger than the move just played, that move has been your right.

-- Translated by John Fairbairn

As stated, there is some ambiguity, but O clears that up in the ensuing discussion. He regards the size of "the move just played" as the same as the size of the reverse sente by the opponent. But the size of the next move is the size of the threat, not the size of the reply. In the example he gives, the threat is a gote, so the size of the reply is the same as the size of the threat. I expect that if O saw an example where the reply is a reverse sente, he would get it right, and his readers might, as well, I don't know. But his definition is in terms of the sizes of the sente and its threat, not the sizes of the reverse sente and the reply.

It may be counterintuitive to think of a sente play in terms of the opponent's plays, but that's what makes it sente. Yes, a sente raises the local temperature, but it is the opponent's plays that indicate the current temperature.