Sigmoid is much better because the shape recognizes that it is the scores near 0 that are most important to differentiate. Going from +1 to +4 is much more significant than going from +10 to +14.flok wrote: ↑Mon Jul 01, 2019 8:02 amSo instead I could also do (score + 10000) / 20000 ? (assuming eval score range is -10k ... 10k)Ronald wrote: ↑Thu Jun 27, 2019 7:21 pmHi Folkert,
The sigmoid function is used to map the score of the evaluation (which is f.i. in the range of -100 to +100) to a value in the range of 0 to 1.
A score of -infinity results in a value of 0, a score of +infinity in a value of 1. A score of 0 results in a value of the sigmoid of 0.5.
tuning for the uninformed
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Re: tuning for the uninformed
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Re: tuning for the uninformed
But not if you actually want to be able to win in a +10 position...
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Re: tuning for the uninformed
That is why we need search, it is very likely that with an advantage of +10 (I assume 10 pawns) the check-mate will be in the horizon of a decent search. Nowadays most engines can find a check-mate in (lets say 20 moves) in just a few seconds.
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Re: tuning for the uninformed
Some King attacks are still not trivial for programs to execute, especially when there are quiet moves (zwischenzuegen) in the PV, or one or more sacrifices are involved.
--Jon
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Re: tuning for the uninformed
Programs that prune less are usually better at these type of positions. There clearly is a difference between finding the check-mate in a position with an already +10 material advantage or finding a combination that leads to mate in a more or less equal position.
Having a very good evaluation of king-safety really helps, also with pruning decisions, this is an area where NN type engines probably shine. Unfortunately this is where my engine is very bad at.