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Subject: Re: WAC Corrections

Author: Dann Corbit

Date: 17:03:11 04/12/01

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On April 12, 2001 at 15:48:29, Miguel A. Ballicora wrote:

>On April 12, 2001 at 13:24:02, Dann Corbit wrote:
>
>>On April 12, 2001 at 10:45:23, Alex Szabo wrote:
>
>>>
>>>	Problem		Solution Change		Comment
>>>	=======		===============		=======
>>>
>>>	#22		Bc4-a2			additional solution
>>Agree.
>>
>
>Good! I was going to post a question about this one when you guys started a
>discussion about the whole WAC!
>I don't think I can agree on WAC.022. Nxf7 gets back the a destroying the
>black pawn structure. Can we say that Ba2 is equivalent? I do not think so.
>Pf7 is much more valuable than Pe4!
>My program Gaviota oscilates between Ba2 and Nxe6. Nxe6 looks nicer to me
>than Ba2, but still I think is an equivalent of Nxf7.
>I think that the only solution should be Nxf7.
>Is there something that I don't see?

Here is the position in question:
[D]r1bqk2r/ppp1nppp/4p3/n5N1/2BPp3/P1P5/2P2PPP/R1BQK2R w KQkq - acd 16; acn
535932039; acs 1001; bm Ba2 Nxf7; ce 52; id "WAC.022"; pv Nxf7 Kxf7 Qh5+ g6 Qxa5
Nd5 O-O a6 Bxd5 exd5 Bf4 b6 Qb4 Bg4 Be5 Rf8 Rae1;

Let's formulate the sensible alternatives and analyze them:
First, what does it look like for black, after Nxe6?
[D]r1bqk2r/ppp1nppp/4N3/n7/2BPp3/P1P5/2P2PPP/R1BQK2R b KQkq - acd 17; acn
505593971; acs 1000; bm Ba2 Nxf7; ce 36; id "WAC.022 after Nxe6"; pv Bxe6 Bxe6
fxe6 Qh5+ Ng6 Qxa5 O-O Qg5 e5 Rb1 b6 Qe3 Nh4 O-O Nf5 Qxe4 exd4 cxd4 Qxd4;

As you can see, black now has a positive eval.  Hence, that was not such a great
choice.

Next, what does it look like for black, after Ba2?
[D]r1bqk2r/ppp1nppp/4p3/n5N1/3Pp3/P1P5/B1P2PPP/R1BQK2R b KQkq - acd 14; acn
476907529; acs 999; bm Ba2 Nxf7; ce -46; id "WAC.022 after Ba2"; pv O-O Qh5 h6
Nxe4 Nf5 O-O b6 Ng3 Qd6 Nxf5 exf5 Qf3 Be6 Bf4 Qe7 Bxe6 fxe6;

The negative score shows that black is still in trouble, with an eval of about
-1/2 pawn (about the same as our original evaluation of the starting position).

Next, what does it look like for black, after Nxf7?
[D]r1bqk2r/ppp1nNpp/4p3/n7/2BPp3/P1P5/2P2PPP/R1BQK2R b KQkq - acd 16; acn
452677174; acs 1001; bm Ba2 Nxf7; ce -113; id "WAC.022 after Nxf7"; pv Kxf7 Qh5+
Kg8 Qxa5 Nd5 Bxd5 exd5 Bf4 Qd7 Bxc7 Qc6 Be5 b6 Qb4 a5 Qb2;

Now we see the brilliance of Nxf7.  Often, after making the key move, the
evaluation becomes much more clear.

Next, what does it look like for black, after Qh5 (not mentioned, but it also
looks feasible to me)?
[D]r1bqk2r/ppp1nppp/4p3/n5NQ/2BPp3/P1P5/2P2PPP/R1B1K2R b KQkq - acd 16; acn
337761675; acs 999; bm Ba2 Nxf7; ce 72; id "WAC.022 after Qh5"; pv g6 Qe2 Nxc4
Qxc4 Qd5 Qxc7 h6 Nh3 e5 Qxe5 Qxe5 dxe5 Bxh3 gxh3 O-O-O;

As you can see, black now has a positive eval.  Hence, that was not such a great
choice.

Here is the game in question:

[Event "Tournament"]
[Site "Leningrad (Russia)"]
[Date "1934.??.??"]
[Round "?"]
[White "Romanovsky Petr (RUS)"]
[Black "Yudovich Mikhail M (s) (RUS)"]
[Result "1-0"]
[ECO "C15"]
[Opening "French"]
[Variation "Winawer, Nimzovich variation"]

1. e4 e6 2. d4 d5 3. Nc3 Bb4 4. a3 Bxc3+ 5. bxc3 Ne7 6. Nf3 dxe4 7. Ng5
Nbc6 8. Bc4 Na5 9. Nxf7 Kxf7 10. Qh5+ g6 11. Qxa5 Nd5 12. O-O Re8 13. Bd2
b6 14. Qb5 Bb7 15. Rae1 a6 16. Qb1 b5 17. Rxe4 Qd6 18. Bxd5 Bxd5 19. Rh4 h5
20. Qc1 Ke7 21. c4 1-0

I think probably Nxf7 is the best move.  But Ba2 has a positive eval and might
have merit.  I don't think any other choices are really worth considering.  So
it might be worthwhile to have Ba2 analyzed for 10 hours or so, and also to have
a human expert go over it.



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