Thread: White 34
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Old 2014-06-29, 00:14   #3
cheesehead
 
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"Richard B. Woods"
Aug 2002
Wisconsin USA

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[QUOTE=WMHalsdorf;376961]33 Nxc8 Kxe6 34 Bh3+ Kf6 35 Rb6+ Kf7 36 Rb7 Bb4 37 Nxe7 Bxe7 38 Ra7
If 38 ... Nb3 or Nc4 then 39. Bf1 Should be able to pick up another pawn.[/QUOTE]Yes, but not the a-pawn anytime soon.

One problem with Bf1 is that the square from which the bishop will attack the knight, c4, is vulnerable to counterattack by the knight, thus deterring our rook from taking on a5 before Black can play ... Bb4. The other is that the Black king can un-pin itself so as to allow Bc5+ threats, and we can't stop the unpinning without getting into repetition of position:

If [B]38 ... Nb3 39 Bf1 Kf8 40 Bc4 Nd2[/B]
If [B]41 B-moves Bc5+[/B]
If [B]41 Rc7[/B] now the rook isn't threatening to capture the a-pawn.
If [B]40 Ra8+ Kg7[/B]
If [B]41 Bc4 Nd2[/B]
If [B]42 B-moves Bb4[/B] and the a-pawn is protected.
If [B]41 Ra7 Kf8[/B] leads to repetition of position, or else White stops checking the king, allowing Black to get in Bc5+ or Bb4.

If [B]38 ... Nc4 39 Bf1 Kf8[/B]
If [B]40 Bxc4 Bc5+[/B]
If [B]40 Kg2 Ne3+ and 41... Nxf1 and 42... Bb4[/B] and the a-pawn is protected.
If [B]40 Kh1 Nd2 41 Bd3 Bb4[/B] and the a-pawn is protected. (Sure, 42 Bxg6, but we were going to get the king-side pawns eventually anyway. The point of this analysis is that we don't have a forced capture of the a-pawn as I'd originally thought.)

- - -

Now for why I came here:
[QUOTE=cheesehead;376956]
If [B]41 Be6[/B] attacking the knight, it's not a check, so Black can move the knight. But if then 42 Rxa5 Kxe6.
In particular,
If (with knight on b3) [B]41 ... Nd4[/B] attacking the bishop, and there aren't any Black targets that our B can threaten when it moves.[/QUOTE]and
If [B]42 Rxa5[/B]
If [B]42 ... Kxe6 43 Rxc5[/B] we've won the pawn, but
If [B]42 ... Nxe6[/B] we've lost a bishop for a pawn.

Last fiddled with by cheesehead on 2014-06-29 at 00:45
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