Author: Mike S.
Date: 05:58:25 11/30/02
Go up one level in this thread
On November 29, 2002 at 20:21:12, John Merlino wrote: >(...) >>>[D]8/2q1p1k1/3pP1p1/2pPNpNp/2P2B2/1p1B2K1/1P1R4/r7 w - - 0 42 >>>CM9000, on a humble P3-733, finds 42.Nxg6! in 21 seconds. How do other engines >>>fare? >> >>Analysis by Nimzo 8 (P3/700, 64 MB hash): >> >>1.Nd7 Qa7 2.Rf2 Qa2 3.Kh2 >> ± (0.87) Depth: 1/11 00:00:00 58kN >> ± (0.76) Depth: 5/17 00:00:00 58kN >>1.Nc6 Ra8 2.Nf7 Re8 3.Rf2 Kh7 4.Bg5 h4+ >> ± (0.77) Depth: 5/17 00:00:00 58kN >> +- (1.62) Depth: 10/25 00:00:07 2694kN >>1.Ngf7 Kh7 2.Nxg6 Rg1+ 3.Kh2 Rxg6 4.Bxf5 Kg7 5.Re2 Rg4 6.Bxg4 >> +- (1.63) Depth: 10/25 00:00:13 5667kN >> +- (2.34) Depth: 11/26 00:00:43 19670kN >>1.Nxg6 Rg1+ 2.Kh2 Rg4 3.Rf2 Kxg6 4.Bxf5+ Kg7 5.Bxg4 hxg4 6.Rg2 >> +- (2.35) Depth: 11/26 00:00:46 21624kN >> +- (3.21) Depth: 13/29 00:01:23 38980kN >> >>(...) >>After 1.Nxg6 Kxg6? 2.Kh2 (as you mentioned), Black has no defense against the >>threat 3.Rg2 and 4.Nf7+ Kf6 5.Bg5+ Kg7 6.Bxe7+ Kh7 7.Bxf5# >Thanks for that analysis. I wondered if Nxg6 could be played later or if it was >necessary immediately. But, according to your output above, doesn't Nimzo decide >on Nxg6 after 46 seconds? I would be curious to see what its output is after a >few more minutes, since you appeared to stop the analysis after less than a >minute and a half. Does Nimzo eventually switch to Ngf7 like Yace does? Yesterday I did wait a bit longer, but Nimzo didn't come up with a new mainvariant after ~3 minutes. To repeat the test, I removed the learn file and let it run for 15 minutes (while surfing the web): Analysis by Nimzo 8: 1.Nd7 Qa7 2.Rf2 Qa2 3.Kh2 ± (0.87) Depth: 1/11 00:00:00 ± (0.76) Depth: 5/17 00:00:00 1.Nc6 Ra8 2.Nf7 Re8 3.Rf2 Qb7 4.Bh6+ Kg8 5.Bg5 Kh7 6.Kh2 ± (0.77) Depth: 5/17 00:00:00 +- (1.63) Depth: 10/25 00:00:08 2363kN 1.Ngf7 Kh7 2.Nxg6 Rg1+ 3.Kh2 Rxg6 4.Bxf5 Kg7 5.Rd3 Qb6 6.Bxg6 +- (1.64) Depth: 10/25 00:00:20 7487kN +- (2.50) Depth: 11/26 00:01:04 27245kN 1.Nxg6 Rg1+ 2.Kh2 Rg4 3.Rf2 Kxg6 4.Bxf5+ Kg7 5.Bxg4 hxg4 6.Rg2 +- (2.51) Depth: 11/26 00:01:06 28244kN +- (3.37) Depth: 15/32 00:09:22 275483kN I have now idea why some evaluations today are different from yesterday's, but anyway, Nimzo likes 1.Nxg6 more. Now, I switched to multi-pv mode during the analysis above, and let it calculate for some more minutes: Analysis by Nimzo 8 (during depth 13): 1. +- (3.21): 1.Nxg6 Rg1+ 2.Kh2 Rg4 3.Rf2 Kxg6 4.Bxf5+ Kg7 5.Bxg4 hxg4 6.Rg2 2. +- (1.94): 1.Ngf7 Qa5 2.Nc6 Rg1+ 3.Kf3 Qa1 4.Nxe7 Rg4 5.Rh2 Rxf4+ 6.Kxf4 It seems that 1...Qa5 is more annoying for White after 1.Ngf7 here (than after 1.Nxg6 Kxg6 2.Kh2 as you mentioned it), with counter-threats for Black as his queen can enter White's position to support the rook. So it seems it's not just a simple transposition (as I thought yesterday), and these two first moves are not exchangeable... but probably both winning. For second and third opinions, it may be useful to cross-check with other fast tacticians, i.e. Fritz 7, Fritz 7 NoMMX or Ruffian, and also with (Little) Goliath Light, or Patzer, to eventually spot Black perpetuals after 1.Ngf7. The variants are a bit complicated :o) Regards, Mike Scheidl
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.