Uri Blass wrote: ↑Fri Aug 16, 2019 3:02 pm

Even with this metric it is possible that 2 moves are the same.

Here is a simple example

At least you didn't post a position with just two naked Kings

So, can white win here with some series of black moves? Then, assume black wants to get checkmated, and it cooperates with white to achieve this. What's the white moves that allow white to mate black the fastest? Otherwise, assume black is a random player, then white plays the moves that increase the chance that black plays those random moves that allow white to mate them.

In all these cases, white can rank its moves, and the one at the top is the best one. They're not equal, equality assumes best play (black can secure a draw no matter what white plays), but you don't know if your opponent will play those best moves (there's a non-zero chance that they have a mouse slip and give up the game), so there's a move that maximizes your chances of winning.

Zenmastur wrote: ↑Fri Aug 16, 2019 7:23 pm

And I didn't do further analysis on the lines of play that it gave, mostly because I believe the lines are accurate enough to show that this position is "equal" and there is NO BEST MOVE!

And THIS is the reason talking about "best moves" makes no sense whatsoever, unless there's a game happening from that position, white is someone, black is someone, and white is trying to win. Then and only then, this person controlling the black pieces has some strength, and there's a series of moves white can play that defeat this strength, and from those there's a string that gets black mated in the shortest amount of moves.

Because black can't play perfectly.

So, let's say you know for a fact that the black player will play Stockfish Depth 22 moves, single threaded, at MultiPV=4. You can predict all its moves. Aren't you able to find a game continuation that ensures that you as white, win? I think you could if you tried. And then you'll find that this is easier to do with some moves than with others, and then you'd rank the moves, and find one that is clearly best. And if you were black, chances are someone in the world would be able to find a string of moves that would defeat any defense you can come up with.

At least, if some alien race came from space and told humanity that they have to defeat you as white from that position, and everyone gathered their resources to beat you, they could find the string that beats your strength, and a white move would be clearly best for this, over the others. That's THE BEST MOVE.

In this game I posted my opponent played a move weaker than Stockfish Depth 22:

19/27 0:01 -0.02 17...Ned7 18.Ng3 Nh7 19.Bf4 Bxc3 20.Qxc3 Qxc3+ 21.bxc3 Ne5 22.Ne4 Rad8 23.Kb2 Kg7 24.Kb3 b6 25.Rde1 a5 26.a4 f6 27.Nf2 Bf5 28.h4 Kf7 29.Ng4 Ke7 (5.778.796) 3694

19/09 0:01 0.00 17...a6 18.Ne4 Qxd2+ 19.Nfxd2 Nxe4 20.Nxe4 Nd7 21.Bd3 Ne5 (5.778.796) 3694

19/39 0:01 +0.05 17...Rab8 18.Ne4 Qxd2+ 19.Nfxd2 Nxe4 20.Nxe4 Nd7 21.Bf4 Bf5 22.Bxd6 Rbd8 23.Rge1 Bxe4 24.fxe4 Rxe4 25.Bd3 Ree8 26.Bg3 Be5 27.Bc2 Bxg3 28.hxg3 Nf6 29.Kd2 Rxe1 30.Rxe1 (5.778.796) 3694

19/28 0:01 +0.16 17...b5 18.cxb5 c4 19.Bxf6 Bxf6 20.Ne4 Qd8 21.Nxf6+ Qxf6 22.Ng3 Nd3+ 23.Kb1 Re3 24.Ne4 Qd4 25.Nxd6 Qxb2+ 26.Qxb2 Nxb2 27.Kxb2 Rxe2+ 28.Kc3 Rxa2 29.Nxc4 Rc8 30.Kb4 (5.778.796) 3694

20/29 0:02 -0.20 17...Ned7 18.Ng3 Nh7 19.Bf4 Bxc3 20.Qxc3 Qxc3+ 21.bxc3 Ne5 22.Ne4 Rad8 23.Kb2 Kg7 24.Kb3 b6 25.Rde1 Bf5 26.Ng3 Bd7 27.h4 Nf6 28.Bg5 b5 29.Bxf6+ Kxf6 30.Ne4+ Ke7 (9.888.797) 3576

20/09 0:02 0.00 17...a6 18.Ne4 Qxd2+ 19.Nfxd2 Nxe4 20.Nxe4 Nd7 21.Bd3 Ne5 (9.888.797) 3576

20/39 0:02 +0.06 17...b5 18.cxb5 c4 19.Bxf6 Bxf6 20.Ne4 Qd8 21.Ne3 Bg7 22.Kb1 Bh6 23.Qc3 Bxe3 24.Qxe3 Bf5 25.Ka1 Bxe4 26.fxe4 Qa5 27.Rdf1 Qxb5 28.Qh6 Rab8 (9.888.797) 3576

20/36 0:02 +0.11 17...Bxf1 18.Rdxf1 Ned7 19.Kb1 Nh7 20.Bf4 Bxc3 21.bxc3 Nhf6 22.Bd3 Nh5 23.Bxg6 fxg6 24.Rxg6+ Kf7 25.Rfg1 Ndf6 26.Bh6 Re5 27.Qc2 Ke7 28.Bg5 Rh8 29.Ka1 (9.888.797) 3576

21/30 0:06 -0.51 17...Ned7 18.Ng3 a6 19.Bh6 Bh8 20.Kb1 b5 21.Nce4 Qxd2 22.Rxd2 Nxe4 23.Nxe4 Bf5 24.cxb5 Nf6 25.bxa6 Kh7 26.Bg5 Nxe4 27.fxe4 Rxe4 28.Bd3 Rb4 29.Bxf5 gxf5 30.Be3 Rxa6 (20.787.966) 3461

21/36 0:06 +0.08 17...b5 18.cxb5 c4 19.Bxf6 Bxf6 20.Ne4 Qd8 21.Nxf6+ Qxf6 22.Ng3 Nd3+ 23.Bxd3 cxd3 24.Qxd3 Qf4+ 25.Kb1 Re3 26.Qd4 Rxf3 27.Ka1 Bf5 28.Qxf4 Rxf4 29.Nxf5 Rxf5 30.a4 Kg7 (20.787.966) 3461

21/41 0:06 +0.17 17...a6 18.Ne4 Qxd2+ 19.Nfxd2 Nxe4 20.Nxe4 Nd7 21.Bf4 Bf5 22.Bxd6 Bxe4 23.fxe4 Rxe4 24.Bd3 Re3 25.Rg3 Rxg3 26.Bxg3 Re8 27.Kc2 Be5 28.Bxe5 Nxe5 29.d6 Rd8 30.Bf1 Nf3 (20.787.966) 3461

21/23 0:06 +0.49 17...Nh5 18.Bh6 b5 19.cxb5 Qb4 20.Bxg7 Kxg7 21.Ng3 Nf4 (20.787.966) 3461

22/31 0:09 -0.78 17...Ned7 18.Ng3 a6 19.Bh6 Bh8 20.Bf4 b5 21.a3 b4 22.Nce4 Qa4 23.Qc2 Qxc2+ 24.Kxc2 b3+ 25.Kc1 Nxe4 26.Nxe4 Bf5 27.Bxd6 Bxe4 28.fxe4 Rxe4 29.Bd3 Re3 30.Rg3 Bd4 (32.345.354) 3412

22/35 0:09 0.00 17...a6 18.Ne4 Qxd2+ 19.Nfxd2 Nxe4 20.Nxe4 Nd7 21.Bf4 Bf5 22.Ng3 Bh3 23.Ne4 (32.345.354) 3412

22/31 0:09 +0.23 17...b5 18.cxb5 c4 19.Bxf6 Bxf6 20.Ne4 Qd8 21.Nxf6+ Qxf6 22.Ng3 Nd3+ 23.Kb1 Re3 24.Rc1 Qd4 25.Ne4 Bf5 26.Rxc4 Qxb2+ 27.Qxb2 Nxb2 28.Kxb2 Rxe2+ 29.Ka1 Bxe4 30.fxe4 Rxh2 (32.345.354) 3412

22/32 0:09 +0.25 17...Nh5 18.Bh6 b5 19.cxb5 Qb4 20.Bxg7 Kxg7 21.Ng3 Nf4 22.Kb1 Nxe2 23.Qxe2 Nc4 24.Nce4 Re5 25.Rd3 Bd7 26.Rb3 Qa4 27.f4 Rxe4 28.Nxe4 Re8 (32.345.354) 3412

Opponent plays 17...Nfd7?? and loses the game. I'll claim that in this game I played the best moves up to this point, despite what engines think (they'll all like the black side up to this point, or think it's equal.) After this point I don't know, I perhaps could have beaten them faster with some other moves, I chose what was the clearest victory, not the fastest one, but before this, I ranked my moves and played the BEST MOVE up to this position where the blunder was played, and I won.

**Conclusion:**
If the position is being played by white and black, and black is not a perfect opponent, then there's a probability that the black player makes a blunder, and loses the game, depending on their strength. THE BEST MOVE in the position is the one that maximizes those chances to the point at which blunder is unavoidable, so black will play it, and white will win.

If black is nobody and there's no game being played, then analyzing a chess position makes no sense, because black will not play a move, and they can't lose. We'd say the position is draw with best play, most moves are the same, and we move on with our life.

But that's like saying 1.f3 in the opening position is like the other moves, because it's draw with best play. Saying 1.d4/1.e4/1.c4/1.Nf3 are better only makes sense if black is someone you want to beat. But if black is someone you want to beat, and it's an imperfect opponent, then there's a BEST MOVE in the opening position, the one that is the shortest string of moves that allows you to mate them.

Make someone happy today.