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Subject: Re: ECM errata (401 thru 500)

Author: Bruce Moreland

Date: 10:00:13 02/04/98

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On February 04, 1998 at 06:01:52, Amir Ban wrote:

>On February 04, 1998 at 03:12:35, Howard Exner wrote:
>
>>On February 03, 1998 at 15:52:30, Amir Ban wrote:
>>
>>>
>>>Yet another chapter in the ECM saga:
>>>
>>>
>>>No. 411 (Qxd6):
>>>
>>>I get the simple gxh7. Trying Qxd6, it gets about the same score (+3.5).
>>>The position is already very unbalanced anyway, so there may be more.
>>>
>>>Recommend: Scrap it, or add gxh7.
>>
>>Rebel 8 gets 3.16 for Qxd6 and 2.26 for gxh7. My subjective view
>>is that Qxd6 is more decisive.
>>>
>
>Perhaps so. Qxd6 ends up an exchange and a pawn up with the queens
>traded. gxh7 is two pawns up, pawn on seventh and black king stripped.
>Rebel is conservative.

Mine takes Qxd6, but I don't want to get involved in arguments about
positional chess.

>>>
>>>No. 422 (f4):
>>>
>>>I find Qh4 (+92). f4 gets about the same, but I can't find a convincing
>>>continuation after f4 exf4 e5 (or Rb6).
>>>
>>>Recommend: Vague. Drop it.
>>
>>Book is 1.f4 exf4 2.e5 fxe5 3.bxg6 Bc8 4.Rb6 1:0 Is there better choices
>>for black?
>>>
>
>2... f5 looks better, though white is happier in this position. The
>a-pawn gives black counterplay.

I get 1. f4 in a couple of minutes, at +0.97, going up to +1.37 after 42
minutes.

My line is just a strong attack.

I'm worried that interesting positions like this may be cut even if they
turn out to be sound, just because we can't figure out how to win them.

>>>No. 425 (Ng4+):
>>>
>>>The Ng4+ idea works, but I prefer the intermediate Bf5 Qg2 Ng4+.
>>>
>>>Recommend: Add Bf5.
>>
>>Agree

This is a transposition a tempo later, right?

>>>No. 427 (Ne2+):
>>>
>>>Perhaps I have the position wrong. Black is already a queen down and it
>>>looks hopeless. I find Rxg4 for the exciting score of -1209.
>>>
>>>Recommend: Find what the right position is.
>>
>>The Black Queen is on e6 but the key move might want to be changed
>>to Rxg4.

I get Rxg4 with a nice jump here, but I didn't run it longer than 20
seconds.  Howard may very well be right though.  At the least it's
cooked.

>>>No. 434 (Ncxd6):
>>>
>>>This is fairly difficult. Nbxd6 is a transposition.
>>>
>>>Recommend: Add Nbxd6.
>>
>>Agree

They are both +4, so it's either cooked or transposed or both.

>>>No. 440 (Rf3):
>>>
>>>It looks wrong: Rf3 Bd1 and black has egg on his face.
>>>
>>>Recommend: Drop it.
>>
>>Agree as the book missed your Bd1 defense.

I don't find this in an hour on a P2/300.

>>>No. 462 (Nxg6+):
>>>
>>>Wrong position again. I get Qxh7 mate. Mate-in-one problems are rather
>>>easy, for me at least.
>>>
>>>Recommend: Find what the right position is.
>>
>>Remove the white rook on h6. However the move Nxg6 looks too easy.
>>Rebel 8 sees a mate in 0 seconds.

Easy problem, yes.

>>>No. 464 (e5):
>>>
>>>I cannot find the justification for e5. If the idea is e5 dxe5 Ne6 then
>>>counting material actually black gains by it.
>>>
>>>Recommend: Investigate.
>>
>>after black plays dxe5 the book continues with Nf3. Black's defense is
>>not right and I agree that this is a vague position. Drop it as white
>>has
>>other good first moves.

Not found in 4 hours on an alpha.

>>>No. 467 (Rf6):
>>>
>>>I don't see a winning line after Rf6 Qf8 or Ng5. Perhaps it's the best
>>>move, but the assignment is "white wins" and I don't see it.
>>>
>>>Recommend: Investigate.
>>
>>The main book line is the Ng5 defense and loses to Rxg5 but Qf8 seems
>>to hold.

Maybe, but in my line white wins back the d5 pawn, and black is still
pretty cut up.  I only ran it for an hour though, and got +1.23.

>>>No. 470 (Nc3+):
>>>
>>>I don't think this works: 1...Nc3+ 2.Nxc3 bxc3 3.b3 Ra8
>>
>>The book gives Qa6 here and continues 4.Rd4 Ra8 5.Ra4 Qxa4! 0-1
>>
>
>Right, and if 4.Bd4 Bb4. So it's correct.
>>>4.Bd4 and if the
>>>c-pawn falls, what is black's threat ? If now 4...Bc5 5.Qg3.
>>>
>>>Recommend: Investigate.

+1.23 in 22 seconds, +1.87 in 33 minutes.

>>>No. 475 (Rh5):
>>>
>>>Probably correct, but I'm not sure. I followed 1.Rh5 Ne2+ 2.Kh1 Ng3+
>>>3.hxg3 Qxf1+ 4.Kh2 now I see that 4...f6 loses but perhaps 4...h6 5.Bxh6
>>>g6 holds.
>>
>>Be3 will force a mate.
>>
>
>Right. Keep it.
>
>
>>>If it's correct, it should be extremely difficult.
>>
>>Yes this will be a tough one.
>>>
>>>Recommend: Investigate.

I ran this for four hours on the Alpha.  After 34 minutes it had a draw
score.  Next iteration took a huge amount of time to resolve, it ended
up terminating in a fail-high condition, failing high from the draw
score, so the score is still pretty low.

>>>No. 482 (Bxb5+):
>>>
>>>I get h4. Different plan, similar result (+115).
>>>
>>>Recommend: Add h4.
>>
>>Bxb5+ seems more forceful.
>>>
>
>I don't know.

I get 1. h4 for a while and then switch to 1. Bxb5 at 90 seconds at
about +1.2.

>>>No. 488 (Bh3):
>>>
>>>I think it's wrong: Bh3 Ne1 and black is worse than ever.
>>>
>>>Recommend: Drop it.

I get Bh3 at +0.20 after three and a half minutes, +1.64 after 45
minutes.  The line I get is 1. ... g3, so I don't know what happens
after 1. ... Ne1.

>>>No. 489 (Ne4):
>>>
>>>It's wrong: 1...Ne4 2.Nxe4 Rg6 3.Rf1! and if 3...Qe8 4.Rf8+! teaches
>>>black a lesson.
>>>
>>>Recommend: Drop it.
>>
>>Agree

Not found in 4  hours on the alpha.

>>>No. 497 (f5):
>>>
>>>After f5 exd4 I can't find anything to justify a piece (fxg6 hxg6 Bxg6
>>>Nf8).
>>>
>>>Recommend: Investigate.
>>
>>Nf8 is the book defense and continues 4.Bxf7+ Kxf7 5.g6+ Kg7 6.Rdf
>>Bf6 7.Rxf6 1:0
>>The side defense of 3... fxg6 4.Qxe6+ is simply denoted as +- but
>>this line might hold on.
>>>
>
>You mean 4.Qe6+. Seems so. Drop it.

I'm running this now.

>>>No. 500 (f3):
>>>
>>>Looks wrong: 1...f3 2.Nxf3 Qg3 3.Be3 and where is the continuation ?
>>>
>>>Recommend: Drop it.
>>
>>The book continues with 3 ... Bg4 4.Qd6 Be5 0-1. Looks correct. Is
>>there something better than Qd6 though?
>
>No. Rd2 and Qc5 fail. It's correct.

I'm running this now, too.

bruce



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