Thread: White 33
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Old 2014-06-19, 13:18   #3
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"Richard B. Woods"
Aug 2002
Wisconsin USA

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Here's part of the consolidated move analysis that I've double-checked (which is not to say that you guys could not find a mistake). I am pleased to show that in this part (33 ... Kxe6) of the move-tree, we have a forced win of either the a5-pawn or a piece, except that there is one branch at move 38 that I haven't finished.

(I'll be posting the NOT YET DOUBLE-CHECKED parts as soon as I've finished them.)

If [B]33 Nxc8[/B]

If [B]33 ... Nxc8 34 Bh3[/B]

If [B]33 ... Kxe6[/B].
We can pin the N/e7 to Black's king, then use that to pull his B away from a5-defending duty long enough to nab the a-pawn. That requires persuading Black to move his king to f7, [I]while always being on guard not to allow Black to skewer our K and R with his B.[/I] (Moving our K off the a7-g1 diagonal would be a good way to avoid the skewer, but it'll be tough to find a place where we can afford to spend that tempo while maintaining the pin.)

[B]34 Bh3+[/B] gives our king another flight square in case of (or to avoid) future check from Bd4+ or Bc5+, _and_ reduces the number of squares from which the Black king can defend the N/e7.

If [B]34 ... Kf6[/B] (or ... Kf7 35 Rb7) [B]35 Rb6+ Kf7 36 Rb7[/B]. [I](Note that we place our rook on the a7-g1 diagonal _only_ when giving check, allowing Black no chance to skewer)[/I] Now the N/e7 is both pinned and double-attacked, forcing Black to use his B to defend it.

[B]36 ... Bb4 (or Bf7) 37 Nxe7 Bxe7[/B]. Now we've (1) pulled the B off a5-defending duty and (2) pinned it to the king, allowing us to put our rook on the a7-g1 diagonal without immediate skewer.

[B]38 Ra7[/B] threatens 39 Rxa5, [I]but the R is now on the same diagonal as our K, so before Black's B can move again, we must remember to move our K or R[/I].
Black can protect a5 with his N from b3 or c4, so we have to devise a way to drive it away from those two positions.

If [B]38 ... Nb3 39 [/B] (THIS BRANCH IS NOT YET DOUBLE-CHECKED, though I expect it also to result in our capture of either the a5-pawn or a piece)

If [B]38 ... Nc4 39 Bf1[/B] chases the knight away from a5-guard duty, but not before possible complications if Black un-pins his B.

If [B]39 ... Ke8 or Kf6 or Kf8 (not ... Ke6 40 Bxc4+)[/B] threatens the ... Bxc5+ skewer. but we now have just one tempo for moving our king because Black can't defend both of our attack targets (a5 and c4) with one move.
[B]40 Kg2[/B]. Next we will soon capture one of our targets - but only after complications in one case.

If [B]40 ... any K-move or pawn-move 41 Bxc4[/B]
If [B]40 ... Bc5 41 Ra8+ (or Ra6+) K-moves 42 Bxc4[/B]
If [B]40 ... any B-move except Bc5 41 Bxc4[/B]
If [B]40 ... any N-move except Nf3+ 41 Rxa5[/B]

If [B]40 ... Ne3+[/B] Black complicates, but as far as I've analyzed none can harm us, and we will eventually succeed in capturing at least one of our targets on a5 and c4.

[B]41 Kf2[/B]. We can place our king back on the dark diagonal because it's shielded by the N/e3 from a check via ... Bc5.

If [B]41 ... Bc5 42 Rxa5[/B]. We can nab the pawn here because [I](rather amazingly) [U]none[/U] of the eight possible discovered checks from 42 ... N-move can harm us![/I]
If [B]42 ... Nc2+ 43 Rxc5[/B]
If [B]42 ... Nc4+ 43 Rxc5[/B]
If [B]42 ... Nd1+ 43 Kf3[/B]
If [B]42 ... Nd5+ 43 Rxc5[/B]
If [B]42 ... Nxf1+ 43 Kxf1[/B] (not 43 Rxc5 Nxh2)
If [B]42 ... Nf5+ 43 Rxc5[/B]
If [B]42 ... Ng2+ 43 Rxc5[/B]
If [B]42 ... Ng4+ 43 Ke2[/B] If [B]43 ... Nxh2 44 Rxc5[/B]

If [B]41 ... Nxf1 42 Kxf1[/B]
If [B]42 ... Bb4[/B]
Now Black has made it necessary for our king to travel to assist our rook if we want to capture the a-pawn. But if we were to do just exactly that, Black's king might travel down to take our g&h pawns and then march his g&h passers down to victory.

(I'm not going to try counting moves _now_ to see whether we could win a king/pawn-race, but we can do that later if this position does arise.)

By themselves the Black a-pawn and B/b4 pose no offensive threat. Our a-pawn can continue to block theirs by itself (as long as we prevent Black's king from reaching it), while we switch our rook to the king-side.


Last fiddled with by cheesehead on 2014-06-19 at 13:29
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