Author: Robert Hyatt
Date: 16:52:04 02/15/98
Go up one level in this thread
On February 15, 1998 at 17:41:13, Amir Ban wrote: > >The group ECM 601 thru 700 is the most difficult part of the suite, >though the remaining part till the end is almost as hard. I solve only >60 out of 100 of these in under 60 seconds on P6/200. > >The first half is mostly endgame positions, some of them pretty and very >difficult (e.g. 603,605,607,608,615,621,626,640). The second half is >mostly "routine" sacrifices on h7/h2. > >Since I had to go through many positions, I decided to break at 680 and >post this: > > >No. 601 (g4): > >This is a draw assignment. I don't know about this one, and I don't find >any clear line here. It seems to be a positional test: If 1...g4 2.h4 >and then white can make many different tries to win, and maybe they all >fail. It looks like g4 is intented to prevent g4 by white, but I'm not >convinced that failing to play g4 loses. E.g. 1...Kg6 2.g4 how does >white win ? > >Recommend: Someone explain what this position is about. > > >No. 617 (Rxa6): > >The idea is clear: 1.Rxa6 Rxa6 2.d6! Qxe5 3.fxe5, but is it good enough >to win ? > >Recommend: Investigate. > > >No. 623 (Rc4): > >After 1...Rc4 white mustn't take on c4, but the continuation 2.Rc1 Bc5 >3.Kg2 Bxf2 4.Kxf2 is not an obvious win. I find Bc5 which is also not >decisive. > >Recommend: Investigate. > > at depth=8, 1.5 seconds, I fail high on Bc5 with a score of +1.5, from the previous best of -.5... at depth=9, 3.21 seconds I switch to Rc4 which is +1.83, not decisively better than Bc5. >No. 624 (Qe6): > >1.Qe6 Qe3 and I cannot find the win. Instead, I think 1.Kh2 wins. This >is a complicated position to be sure. > >Recommend: Change key to Kh2. > I also get Kh2, but it drops every iteration. I only searched these to 20 seconds however... but at the end, depth=8, score=+2.47. > >No. 627 (Qxe7): > >The key works, but I find a fantastic cook: 1.Rxd8 Rxd8 2.Rxg7+! Kh8! >3.Be2! Qe5! 4.Rxh7! Kg8 5.f4! wins. > I find Rxd8 in < .1 seconds, eval=+2.9, and stick with it.. >Recommend: Add Rxd8. > > >No. 629 (b2+): > >I play here Kd6. I evaluate b2+ as a blunder, and can't find any merit >to it. > >Recommend: Drop it. I get Kd6 also. eval=+0.02 But something might happen differently at deeper depths? > > >No. 634 (Rxe3): > >I find Kh7, and next move Rxe3 kills white quickly. Playing Rxe3 >immediately does win, but the black king on g7 makes it complicated. > >Recommend: Add Kh7. > I get Kh7, +4 at about 1/2 second. I change to Rxe3 at 6 seconds, score is +4.5... they seem fairly close... > >No. 636 (Rxf6): > >I don't find this. The line 1.Rxf6 Rxf6 2.Rd7 Rg6 3.Qf5 Qc8 4.e7 Qe8 >5.Qd3 Re6 6.Rd8 Rxe7 is good for white, but maybe not decisive. > >Recommend: Investigate. > > >No. 653 (Bb5): > >This is from the WAC errata. The right move is Rh1. > >Recommend: Change key to Rh1. agree... Rh1 is correct, +3 > > >No. 665 (Bxh7+): > >After 1.Bxh7+ Kxh7 2.Qh5+ Kg8 3.Rf3 I'm still unclear on this since >black has resources such as Nf6, Nf4, g6. They may all ultimately fail, >I guess. > >Recommend: Investigate. > > >No. 674 (Nxh7): > >I find Bxe6 (+96). I don't find the line 1.Nxh7 Kxh7 2.Qh5+ Kg8 3.f5 d6 >to be better. > >Recommend: Drop it. > I also get Bxe6, +.5. But I only searched to 20 seconds, depth=8. > >Amir
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