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I think Crystal must have an eval bug

Posted: Sun Jun 14, 2020 8:52 am
by Dann Corbit
If you look at the current TCEC games, in each and every game, Crystal draws a sawtooth pattern while no other engine does that.
Possible explanation:
A term that should be applied to black's score is applied to white or vice versa.
Just examine any game. Something is not what it ought to be.

There could be some other explanation, but that is the only one that occurs to me.

Re: I think Crystal must have an eval bug

Posted: Sun Jun 14, 2020 12:52 pm
by jhellis3
No...

Crystal does not touch eval except to reduce it for shuffling. What you are perceiving is the result of mcts eval being very stable and Crystal exploring suboptimal paths, correcting the score, and switching off of them.

Re: I think Crystal must have an eval bug

Posted: Sun Jun 14, 2020 1:04 pm
by Dann Corbit
The other AB engines (even SF) do not appear to behave in the same way.

Re: I think Crystal must have an eval bug

Posted: Sun Jun 14, 2020 1:20 pm
by jhellis3
Yes, Crystal will often have the most unstable eval out of all the engines, by design. At least when the position is not a draw :wink: .

The other AB engines do not have progress detection (or at least not to the level of Crystal) either.

There are also many situations where Crystal has had both the most stable and most accurate eval for the vast majority of the game.

People classifying any unexpected behavior as a bug is tiresome.

If one desires a more stable eval from Crystal, try zooming out on the graph, works wonders.

Re: I think Crystal must have an eval bug

Posted: Sun Jun 14, 2020 9:38 pm
by Ovyron
Yeah, a "bug" is an unexpected behavior that appeared and wasn't intended by the programmer. No matter how weird it looks, if it's there by design it can't be a "bug".

Re: I think Crystal must have an eval bug

Posted: Mon Jun 15, 2020 12:02 am
by Dann Corbit
jhellis3 wrote:
Sun Jun 14, 2020 1:20 pm
Yes, Crystal will often have the most unstable eval out of all the engines, by design. At least when the position is not a draw :wink: .

The other AB engines do not have progress detection (or at least not to the level of Crystal) either.

There are also many situations where Crystal has had both the most stable and most accurate eval for the vast majority of the game.

People classifying any unexpected behavior as a bug is tiresome.

If one desires a more stable eval from Crystal, try zooming out on the graph, works wonders.
My mistake, and I do repent on bended knee in dust and ashes.
:oops: