jp wrote: ↑Fri Nov 30, 2018 4:53 pm
chrisw wrote: ↑Fri Nov 30, 2018 2:40 pm
jp wrote: ↑Fri Nov 30, 2018 1:03 pm
What do Leela etc. do re. W/D/L vs. W/L?
treat as one continuous value, I think, last time I looked. value is not treated as categorical, the trained network output is a value between 0 and 1, representing win probablity.
I've been wanting to check what that means. Does 0.7 mean win prob. 70% and combined draw & loss prob. 30% (not distinguishing between D & L), or does it mean something else (e.g. expected score, Pr(win)+ (1/2).Pr(draw))?
it means the same as a typical AB program score, they are convertible between centipawns and win chances via formula. okay, so you ask what is “win chance”, good question, nobody programming cares much, the idea is just to maximise the magic number.
for AB the number comes from adding up some chessic features. The fact, for example, that you will win 100% of your games against any entity, however strong, if you are +5 for KRK or +9 for KQK, tells you that this AB score is not really a “win chance”.
Likewise NN, might say 90% or something, when you know its 100% against any entity.
The NN win prob, is actually the result of hitting the network during training with either a 1 or a 0 or a -1, in similar positions, say 10,000 times, when it got hit maybe 6000 times with 1, 3000 times with 0 and 1000 times with -1. Okay I cheat a little, but this going to give 0.9 or whatever. And this means? errrrm, doesn’t matter, what counts is that this 0.9 is greater than 0.87 someplace else, so the algorithm “knows what to do”.
Ultimately, the problem rests with those endusers, encouraged by those who really ought to know better, who spread the narrative that these scores are exact and accurate and correct and meaningful and all you need is mega silicon bucks plus Stockfish or whatever. Then you have god and can prove anything.
So to answer your question. The value is a magic number whose task is to provide direction by comparing it with other magic numbers. Avoid trying to treat it as anything absolute, cos it isn’t.