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AlphaZero (Computer) vs Stockfish (Computer)
AlphaZero - Stockfish (2017), London ENG, Dec-04
Queen's Indian Defense: Classical Variation. Polugayevsky Gambit (E17)  ·  1-0


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Kibitzer's Corner
Premium Chessgames Member
  Cucurbit: 21. Bg5 is unearthly.
Dec-07-17  Jamboree: Some people are saying that 21. Bg5!!! should be Move of the Year, but I still haven't seen analysis of all the tactics behind it. They may be so deep that no person (and no computer) has yet figured them out.

I am equally mystified by about 50% of the moves in the seemingly unnecessarily long endgame, in which AlphaZero mysteriously avoids snapping off Stockfish's pawns at various points, even when doing so seemed to pose no risk whatsoever. And then's there's the incomprehensible maneuvering and remaneuvering over and over, only to arrive back at a nearly identical position, and then finally doing something else. Undoubtedly the minor differences in piece placement have huge significance to these computers' brains, but we humans can't discern what that significance is.

Premium Chessgames Member
  Cucurbit: I certainly don't claim to understand it all. Looks dangerous... maybe? Some lines definitely do look bad, and it has many of the effects of a good piece sacrifice, but then again a lot of objectively bad moves have those too.

The endgame is pretty mysterious to me as well.

Premium Chessgames Member
  WorstPlayerEver: Let's see if I can pull the same trick.

21. Bg5 f5 22. Qf4 d5

Maybe it works. You never know :)

Dec-08-17  pajaste: 18...h6!?
Dec-08-17  Artemio: remind me of one of the endgame played by Bobby Fischer against Mark Taimanov in the 1971 Candidate's Quarterfinals..
Dec-08-17  Imran Iskandar: Stockfish completely gets discombobulated by 21. Bg5!!
Premium Chessgames Member
  PhilFeeley: So what happens if 21...hxg5? The house caves in?
Dec-09-17  jack2126: 19....Qh7? SCID Stockfish recommends 19...Qe6 which seems to lead to a draw
Premium Chessgames Member
  zanzibar: <<jack2126> SCID Stockfish recommends 19...Qe6 which seems to lead to a draw>

Of course, the actual move recommended is a function of how deep the engine has been allowed to play. And one wonders how "deeply" the move gets recommended.

It would be more information to also quote the <eval/ply>.

(In fact, maybe even the delta over the 2nd candidate move - something rarely cited, but also as information - e.g. if the continuation is sharp or not).

Dec-09-17  jack2126: Thanks Zanzibar. i need to know more before posting. apparently after 19...Qe6, the scid stockfish did not pursue the 20 g4 line deep enough. when i did, things got ugly for SF.
Premium Chessgames Member
  binMonkey: This is super exciting!
Dec-09-17  sudoplatov: 21...hxg5, 22 ♘xg5 ♕ somewhere, then 23 ♗e4 seems to win at least the Exchange.

Note that Black is giving R+N+N odds at the current moment. A big attack is called for.

Dec-10-17  barkwhile: 21...hxg5 22. Nxg5 Qd3 23. Be4 seems to lead to a lot of trouble for black.
Dec-10-17  Dave12: I tried 21..hxg5 Nxg5. If the Queen goes to d3, than Be4, Qb5 (to prevent Qf5) and now white can play Nxf2+!! with Rxf2 Qg6!. So after Nxg5 we must see Qg8. Now I think Be5 Re8 (I guess, to avoid Bh7. although i'm not sure that after Bh7 Qxh7 Nxh7 Kxh7 he is totally lost.) now I don't know what's next. Qf5? Bc4.
Premium Chessgames Member

click for larger view

<21... hxg5> 22. Nxg5 Qg8 23. Qh4 (23. Re7 Nc5 24. Rae1 Bd3) 23... Re8 24. h6 Bd3 25. Qd4 Rf8 26. Qxd3)

click for larger view

Premium Chessgames Member We stuck Stockfish on 21.? for 5 hours to see if it could come up with 21.Bg5!!

The answer is "no" analysis of move 21.?

Premium Chessgames Member
  zanzibar: <<chessgames> We stuck Stockfish on 21.? for 5 hours to see if it could come up with 21.Bg5!!

The answer is "no" analysis of move 21.?>


I got 21.Bg5 after just 19-ply from my version of Stockfish:


<-0.1 Depth: 19 Nodes: 3334K (889 kn/s) Time: <3.75 s[!]>>

<<1 19 -0.10 21.Bg5>> f5 22.Qf3 d5 23.Nf6 gxf6 24.Bxf6+ Rxf6 25.Re8+ Qg8 26.Rxg8+ Kxg8 27.Re1 Nd7 28.Re7 Nbc5 29.b4 Re6 30.Rxe6 Nxe6 31.Qxf5 Ndf8 32.Qf6 Rc8 33.Qxh6 Be2 34.f4 Ng7 35.f5 Nxh5 (3.75)

<2 19 -0.18 21.b4> d5 22.Nc3 Bc4 23.Bf4 Qg8 24.b5 Na5 25.Bd6 Re8 26.bxc6 Nbxc6 27.Nxd5 Rxe1+ 28.Rxe1 Re8 29.Rxe8 Qxe8 30.Ne3 Qe6 31.Qxe6 Bxe6 32.a4 (3.75)

<3 18 -0.26 21.Nc3> d5 22.b4 Nd6 23.Nxd5 cxd5 24.Bxd5 Bb7 25.Qf3 Bxd5 26.Qxd5 Nd7 27.Qxd6 Rad8 28.Qf4 Nf6 29.Qf3 Rd3 30.Be3 Kg8 31.Rac1 Nd5 32.b5 (3.75)


Disbelievers can find a screenshot here, along with some cryptic commentary:

PS- Damn it <CG>, when are we going to get the round numbers put in for these games, so I can easily refer to this specific game (or any other for that matter)!?

And putting the round number in the game heading on the kibitz list would allow us to keep track of which game is getting what comment, btw.


Premium Chessgames Member
  WorstPlayerEver: <zanzibar>

I belieb the line 21. Bg5 f5 22. Qf3 d5 23. Nxf6 gxf6 24. Bxf6+ Rxf6 25. Re8+ Qg8 26. Rxg8+ Kxg8 27. Qc7 is stronger for White

Premium Chessgames Member
  zanzibar: <WPE> I was evaluating the position from after Black's move 20.

If you play out the game, and then let the engine churn, like <CG> did, 21.Bg5 doesn't show up as a leading candidate move (for me, I typically set MPV = 3, and so it didn't show up in the top-3).

But, and here's the point, play 21.Bg5 (and maybe a few more ply), then back up to the position after 20...Kh8. Now the engine quickly finds 21.Bg5 as leading candidate move (again, one always has to give the depth, i.e. 19-ply).

This is rather odd, that it seems after 5 hours the engine didn't look at the branch of 21.Bg5 to see it was good, but if you force it to (via a walk-thru), it does.


Premium Chessgames Member
  zanzibar: For the record - I never trust the engine moves to far beyond the first candidate moves in a "projection".

For best lines I would suggest a "walk-thru" - say, allowing the engine to go to a fixed depth, play the leading candidate, then rinse and repeat, etc. etc.

Premium Chessgames Member
  Zhbugnoimt: 19..Qe6 loses to 20.g4! (Houdini 5 depth 28)
Dec-13-17  jdoucette: Stockfish 8 sees 21. Bg5 on a measly 8-core machine (not 64-core they were using) in only 1 hour 9 minute, with it obviously winning at 1 hour 22 minutes.

AlphaZero had 1,500 times the computing power of Stockfish (4 TPUs with 180 TFlops *each*, whereas a 72-core monster PC CPU can barely do 0.5 TFlops). But Stockfish only needed 10 times more power to see the same move. What would it do with another 150 times more power on top of that, to put it at equal footing as AlphaZero?

(Or to put it another way, reduce AlphaZero to the same hardware as Stockfish, and 80,000 moves/sec is suddenly only 5 moves/sec.)

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