There is no such thing in a chess engine, at least none of the top ones. If there is, it's packed with magic and guesses.I am fairly sure that when he wrote score he meant win probability.
Contempt is something else.
Moderators: bob, hgm, Harvey Williamson
There is no such thing in a chess engine, at least none of the top ones. If there is, it's packed with magic and guesses.I am fairly sure that when he wrote score he meant win probability.
Note how I also don't have those material values in advance. Though my engine comes up with its own the first time it sees new pieces/boards.a pawn value was computed using conventional pawn-normalized material ratios that are close to those used in strong chess programs (P=1, N=4, B=4.1, R=6, Q=12)
This is why I said the changes have to be interpreted relative to the draw margin. Then multiplying does not change anything, as it would multiply the draw margin too. In orthodox Chess the draw margin is slightly larger than one Pawn.
Calculated. It would be pretty silly entrusting the player to construct the AI. I've had children play this, for exampleI don't know whether piece values have to be given by the user when he defines a new game, or are calculated
I suppose I kind of do. A piece that moves very similar to a rook will be worth roughly what a rook is. However on a board with say, only white tiles, a rook will be worth almost nothing. I think what is tricky here is when there's lots of those pieces - you might even have 40 rook-like pieces. So their material value is somewhat grounded as rook-like, but when you look at the whole board, one rook-like piece can be worth a lot or not much.But you should require that the values have some meaning on an absolute scale
I've read two of the Alpha Go/Zero papers... saying that it runs on probabilities is an enormous oversimplification. The engine does not operate by guessing its percent chance of winning, as I recall. It does have a NN for how worthwhile a search branch is though (a kind of probability). I think the first iteration had two NN, one did this. Now that aspect is combined into one NN.Leela
The output of Leela Zero for Go looks like this:
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NN eval=0.440025
Playouts: 4602, Win: 47.12%, PV: D4 Q4 Q16 D16 R3 R4 Q3 P3 P2 O3 O2 N3 N2 M3 C17 D17 C16 C15
Playouts: 8902, Win: 47.13%, PV: D4 Q4 Q16 D16 R3 R4 Q3 P3 P2 O3 O2 N3 N2 M3 C17 D17 C16 C15 B15 C14
Playouts: 12433, Win: 47.27%, PV: D17 Q16 D15 Q4 D4 C3 D3 C4 C5 B5 C6 B6 C7 B7 C8 B8 C9 B9 C10 B10 C11 B11 C12 B12
D17 -> 6422 (V: 47.58%) (N: 0.62%) PV: D17 D16 C16 E17 C17 D15 C15 D14 C14 D13 D4
D4 -> 1970 (V: 47.04%) (N: 14.49%) PV: D4 Q4 D16 Q16 R3 Q3 R4 R5 S5 R6 S6 R7 S7 R8 R17 R16 Q17 P17 P18 O17 O18 N17 N18 M17
Q4 -> 1669 (V: 46.99%) (N: 13.46%) PV: Q4 D4 Q16 D16 C17 C16 D17 E17 E18 F17 F18 G17 G18 H17 C3 C4 D3 E3 E2 F3 F2 G3 G2
Q16 -> 1603 (V: 47.01%) (N: 12.77%) PV: Q16 Q4 D16 D4 C3 C4 D3 E3 E2 F3 F2 G3 G2 H3 R3 Q3 R4 R5 S5 R6
D16 -> 1544 (V: 46.95%) (N: 13.35%) PV: D16 D4 Q16 Q4 C3 C4 D3 E3 E2 F3 F2 G3 G2 H3 R3 Q3 R4 R5 S5 R6
C16 -> 707 (V: 47.57%) (N: 0.72%) PV: C16 Q16 Q4 D4 E16 R3 R4 Q3 P3 P2 O3 O2 N3 N2 M3 M2 L3 L2
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function AgreeToDraw{
if computer is very easy, return true
if it's the first 20 moves, return false
if DoingSlightlyBadOrWorse return true
if not IsProgressHappening return true
otherwise return false
}
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function DoingSlightlyBadOrWorse{
set whiteStart to the average material value of white pieces in first 5 moves
set whiteRecent to the average material value of white pieces in last 5 moves
set whiteRatio to whiteRecent / whiteStart
// example: if white has lost half its material value, whiteRatio is 0.5
set the same for black
set materialRatio to blackRatio / whiteRatio
// also invert materialRatio if white's turn so >1 is always good for computer.
if materialRatio < 0.8 return true
otherwise return false
}
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function IsProgressHappening{
// MRIM = most recent irreversible move. An irreversible move is like a capture, promotion, etc.
if MRIM is close to start of game, return true
if MRIM is less than 10 moves ago, return true
set stdBeforeIrreversible to standard deviation of AI evaluation scores before MRIM
set stdAfterIrreversible to standard deviation of AI evaluation scores after MRIM
set stdRatio to stdAfterIrreversible / stdBeforeIrreversible
if stdRatio < 0.5 return false
otherwise return true
}