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Subject: Re: Revised ECM Test Suite (some additional analysis needed)

Author: martin fierz

Date: 06:53:51 07/19/04

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On July 19, 2004 at 07:31:35, Omid David Tabibi wrote:

hi omid,

i've tried myself + ruffian at some positions. it would have helped had you
stated yourself what you think of these positions so that we could look for
improvements there (e.g. you could say " i think in ECM xxx the solution Z
doesn't work because ....", or " i think there is an alternative solution X"
etc. )! i've tried to write those things in this post :-)

cheers
  martin

>4. I didn't find any win for the suggested best move, or am not sure whether it
>is indeed the best move. There are 26 such positions which appear below. It
>would be nice if you could analyze them longer and see whether the suggested
>best move is indeed the best, or alternatives should be added:
>

>2bq1b2/1p3k2/1r1p1p1p/pNpP1PpP/P1P3P1/6B1/1P5Q/2K1R3 w - - bm Re6; id "ECM.396";

this looks like a very correct exchange sac which takes a long time to see, but
after Re6 Bxe6 fxe6+ i see no proper defense for black for the various white
threats (invasion of the Q to g6, grabbing a pawn (a5 or d6 or f6)). what kind
of defense do you suggest after Re6?

>rq1r2k1/3nbp1p/p2p2p1/1p1Pp1P1/3B1P2/3B3Q/PPP4P/2KR2R1 w - - bm f5; id
>"ECM.497";

f5 looks good after 1.f5 exd4 2.fxg6 hxg6 3. Bxg6 fxg6 4.Qe6+ Kg7 5. Qxe7+ Kg8
6. Qe6+ Kg7 but is there any way to continue?

>r3k1r1/pb1qpp1p/1pnp1n1B/2p2R2/3PP3/2P3PN/P1P3BP/R2Q3K b q - bm Nxe4; id
>"ECM.561";
i can't see anything clear here, Nxe4 doesn't seem to work

>8/p5k1/2p2p2/4p1p1/1p2P3/1P4PP/1PP5/5K2 b - - bm g4; id "ECM.601";
g4 seems to draw (1...g4 2.h4 a5 and wait - the white king cannot attack the
black pawns because of ...f5! at the right moment; on c3 black plays bxc3 and
continues to wait). but i see nothing for white after 1...Kf7 2.g4 (what else,
since black would transpose back to the 1...g4 line if necessary).

>8/8/4b1p1/2Bp3p/5P1P/1pK1Pk2/8/8 b - - bm g5; id "ECM.605";
this looks like a famous position to me but i don't know where i've seen it
before. the solution would be 1...g5! 2.fxg5 d4+! 3.Bxb4 Kg3, and black wins
because he will take the h4 pawn and win with the two far-separated passers,
while white's 2 pawns are useless because they are stopped by the black bishop
which is simultaneously defending the b3 pawn. it's a "principle of one
diagonal" vs "the pants" situation.


>r1b2rk1/2q1bppp/p1n1p3/1p1np1P1/5P2/1NNBBQ2/PPP4P/R4RK1 w - - bm Bxh7+; id
>"ECM.665";
1. Bxh7+ Kxh7 2. Qh5+ Kg8 3. Rf3 looks like what this should be, 3...g6 4. Qh6
Bd6 (what else?) 5. Rh3 f6 6. Nxd5 exd5 7. Qh8+ Kf7 8.Qxf6+ Ke8 9. Qxg6+ looks
winning, any improvements for black?

>2rqr1k1/1p1bbppp/p3p3/n7/3P2Q1/2PB1N2/P4PPP/R1B1R1K1 w - - bm Bxh7+; id
>"ECM.673";
1.Bxh7+ Kxh7 2. Qh5+ Kg8 3. Ne5 g6 4. Nxg6 Bf6 (what else?) 5.Ne5 is winning for
white, any improvements for black?

>r1b2r1k/ppppq1pp/2n1n3/6N1/2B2P2/4B3/PPP3PP/R2Q1RK1 w - - bm Nxh7; id "ECM.674";
1.Nxh7 Kxh7 2. Qh5+ Kg8 3. f5 Ne5 4. fxe6 Nxc4 5. Rxf8+ Qxf8 6. Rf1 wins for
white, improvements for black?


>r1b2rk1/1pq2ppp/p1p1p3/2n1P3/2N2P2/3B4/PPP3PP/R2Q1RK1 w - - bm Bxh7+; id
>"ECM.677";
1.Bxh7+ Kxh7 2. Qh5+ Kg8 3. Rf3 Ne4 4. Rh3 f5 seems to hold the draw for black,
as white's attacking ideas look dangerous but don't seem to work, e.g. 5. Rd1 b5
6.Nd6 Nxd6 7. Rxd6 Qb6+ 8. Kf1 Ra7 9.Rh6 Ke8 - of course white can always take a
perpetual, but i don't see a win.

>r5k1/pn1q1rpp/2pp4/5R1N/bP6/4BQ2/P4PPP/2R3K1 w - - bm Nxg7; id "ECM.714";
1. Nxg7 Rxg7 2. Bh6 looks great for white, any defense for black??

>4kbr1/pp1bpp1p/3p1p2/3N4/1PBQP3/q7/P1r2PPP/R4RK1 b - - bm Rxg2+; id "ECM.725";
1...Rxg2+ 2.Kxg2 Qh3+ 3. Kg1 Qg4+ 4. Kh1 Qf3+ 5.Kg1 Bh3 6. Ne3 Bh6 looks like
the idea of this puzzle, but does 7. Qd1 hang on now?

>r3r1k1/pbq1ppbp/1pp2np1/4N3/3P4/2P5/PPB1QPPP/R1B1R1K1 w - - bm Nxf7; id
>"ECM.762";
1. Nxf7 Kxf7 2. Qe6+ Kf8 3. Bb3 Nd5 4. Re3 must be the idea here, continue
4...Bf6 5. Rh3 Kg7 6. Bh6+ Kh8 7. Bxd5 exd5 8. Qf7 +- - improvements for black?

>2rqr1k1/pb2bp1p/1pn1pnpB/4N3/3P4/P1N3R1/1P3PPP/RB1Q2K1 w - - bm Rxg6+; id
>"ECM.810";
is this a typo and should be Nxg6? that is winning, Rxg6 looks very bad...

>1q1r3k/3P1pp1/ppBR1n1p/4Q2P/P4P2/8/5PK1/8 w - - bm Rxf6; id "ECM.825";
this is another famous one:
1. Rxf6 Qxe5 2.fxe5 gxf6 3. exf6 easily winning. do you see an alternative
solution? in any case, for a human this is simplest, because there is no chance
of error after 1.Rxf6, it's completely over.

>rr4k1/5p1p/n2p1npQ/q1pP4/6P1/2N2P1N/PP1R3P/2K4R b - - bm Rxb2; id "ECM.853";
1...Rxb2 2.Kxb2 Rb8+ 3. Kc2 Nb4+ 4. Kd1 Qa3 5. Ke2 Qxc3 looks winning for black
- objections?

>6k1/1R4pp/2p5/8/P1rNp3/6Pb/4PK2/8 w - - bm a5; id "ECM.878";
1. a5 draws easily, as in 1.a5 Rxd4 2.a6 Ra4 3. a7 Bc8 4. Rc7 Be6 5. Rb7 =,
other first moves may still have to fight for the draw (1. Ke3, but i think that
should also be good enough for a draw).



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