tapered eval

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flok
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tapered eval

Post by flok » Fri Jul 05, 2019 3:16 pm

Regarding the implementation of tapered eval in https://www.chessprogramming.org/Tapere ... on_example.

At what value (+/-) can you see we're in the endgame?
The range is 0...255, is it half way? At 192?
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zullil
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Re: tapered eval

Post by zullil » Fri Jul 05, 2019 3:28 pm

flok wrote:
Fri Jul 05, 2019 3:16 pm
Regarding the implementation of tapered eval in https://www.chessprogramming.org/Tapere ... on_example.

At what value (+/-) can you see we're in the endgame?
The range is 0...255, is it half way? At 192?
I understand the question, but what is the point of the question?

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flok
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Re: tapered eval

Post by flok » Fri Jul 05, 2019 3:36 pm

zullil wrote:
Fri Jul 05, 2019 3:28 pm
flok wrote:
Fri Jul 05, 2019 3:16 pm
Regarding the implementation of tapered eval in https://www.chessprogramming.org/Tapere ... on_example.

At what value (+/-) can you see we're in the endgame?
The range is 0...255, is it half way? At 192?
I understand the question, but what is the point of the question?
I've got two arrays of values for some eval parameter: one array for mid-game, the other for end-game.
I would like to go smoothly from one to the other, but for that I need to know if the center-point, the point where one no longer speaks of mid-game but of end-game, if that's at 127.5.
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zullil
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Re: tapered eval

Post by zullil » Fri Jul 05, 2019 3:48 pm

flok wrote:
Fri Jul 05, 2019 3:36 pm
zullil wrote:
Fri Jul 05, 2019 3:28 pm
flok wrote:
Fri Jul 05, 2019 3:16 pm
Regarding the implementation of tapered eval in https://www.chessprogramming.org/Tapere ... on_example.

At what value (+/-) can you see we're in the endgame?
The range is 0...255, is it half way? At 192?
I understand the question, but what is the point of the question?
I've got two arrays of values for some eval parameter: one array for mid-game, the other for end-game.
I would like to go smoothly from one to the other, but for that I need to know if the center-point, the point where one no longer speaks of mid-game but of end-game, if that's at 127.5.
I think you should review the material you linked above. The "smooth" transition is accomplished by the changing value of the "phase" variable. Not sure how a "center-point" matters.

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hgm
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Re: tapered eval

Post by hgm » Fri Jul 05, 2019 4:18 pm

The whole point of tapered eval is that there is no such thing as the start of the end-game. Only the start of the game (i.e. all material present) and the end of the game (no non-Pawn material present). You just have to provide these two extreme values for every parameter, and the interpolation formula does the rest.

If the values you considered 'end-game' values before, you should ask yourself for what typical material on the board the values you chose were most suitable. If that was for an early end-game, say with two Rooks and a minor, that would be for totalPhase = 5 rather than 0, and you would have to extrapolate a bit to get the values for totalPhase = 0.

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