Maroczy–Tartakower 1922

[Eelco de Groot]

Hi Peter,

Well, no special reason but 47 was the depth of the analysis from Louis, and with the total nodecounts given it is a good opportunity for me to see if Rainbow Serpent need much more time to reach that depth, without actually having to run it with Stockfish. It saves me a lot of time... But I am more puzzled by such a crazy line from Serpent as 18. Re2?! and then still expecting to almost be equal, it must think that the Rook is rather poisonous. And it is no quick line, it has considerable depth. Re2 is quickly abandoned again but also a lot of 18. Bg2 lines. In case of a poisoned pawn it is easier to understand, but a full Rook! And then the tactics seem to be deep enough that it takes a really long time to see that White is materially a rook up (have not checked the line if Black wins back material at some point), is still under pressure in spite of the material but with hope of a draw in sight. Well, that is why Tartakower wrote as mentioned by Sune that it was a really rare occurence, such a positional sacrifice of a Rook based on general considerations only. I think it really is rare.

Regards, Eelco

[peter]

But I am more puzzled by such a crazy line from Serpent as 18. Re2?! and then still expecting to almost be equal, it must think that the Rook is rather poisonous.

Of course it is!
I had seen this one posting of yours too and already had my SF have a look at it.
At once with then still almost empty hash it marked the continuation 18...Rh6 in your output-variant as to be doubted, ...Qh6 instead had a somewhat better eval first.
Here is what's shown with the now still full hash from the other one Backward:

[d]r1b3k1/pp1n3p/2pbpq2/3p4/2PPp1p1/PP2P1P1/1BQNRP1r/3R1BK1 b - - 0 1

Analysis by Stockfish 270615 64 POPCNT:

18...Qh6 19.Bg2 Nf6 20.Rc1 Bd7 21.Qd1 Rf8 22.Nf1 Rxg2+ 23.Kxg2 Qh3+ 24.Kg1 h5 25.c5 Bc7 26.Nh2 h4 27.Qf1 hxg3 28.Qxh3 gxh3 29.fxg3 Bxg3 30.Bc3 Be8 31.Be1 Bc7 32.Bh4 Kh7 33.Kh1 Bh5 34.Rf2 Bxh2 35.Rxf6 Rxf6 36.Bxf6 Bg3 37.Kg1 Bf3 38.Rc2 Kg6 39.Be7 Kf5 40.Bd6 Bd1 41.Rc1
-/+ (-1.17) Depth: 38/53 00:03:41 3872MN
...
18...Qh6 19.f4
-/+ (-0.95 --) Depth: 39/56 00:07:19 7862MN

I'd say, 18.Re2 was simply playable too, even if with some less chances for White not to lose than after taking the rook- sac, because
after 18...Rh6:

[d]r1b3k1/pp1n3p/2pbpq1r/3p4/2PPp1p1/PP2P1P1/1BQNRP2/3R1BK1 w - - 0 1

Analysis by Stockfish 270615 64 POPCNT:

19.Bg2 Qf5 20.b4 Nf6 21.Qc3 Qh5 22.Nf1 Bd7 23.a4 Ne8 24.Ba3 Bc7 25.b5 Nd6 26.Bxd6 Bxd6 27.Rb1 Rf8 28.Rc2 Bb8 29.Rbb2 Rhf6 30.Qb4 Qf7 31.Qe1 e5 32.bxc6 Bxc6 33.cxd5 Bxd5 34.a5 h5 35.Rc5 exd4
-/+ (-1.27) Depth: 33/47 00:05:39 4718MN

So your Rainbow Serpent even had the stronger cont. for Black after the denying of the sac for Black in output as it seems.
And it did see well, that White's in trouble with a rook up here too.

Congratulating

[Kyodai]

A similar theme just happened in the game Wei Yi-Bruzon, where white
crushed through in Fischer style with a quick f2-f4-f5-fxg6 and then Rxf7,
followed by Qh7+. Here is a link to the game with sparkling comments
by Simon Williams. A new evergreen game produced by an extraordinary
talent, in our times.

https://www.youtube.com/watch?v=hyA4V6v4OuM