<Phony Benoni>: "Tricky. There are a lot of targets in the White position, but the problem is finding which one to hit.

As a lot of solvers probably will, I looked first at 25...Rxd2+ 26.Rxd2 Bb4 skewering the rooks. But that doesn't seem to lead to anything more than exchanges, <especially with the Bb7 hanging.>"

--> Yes, but this can be handled by capture with check, isn't it?

White threatens 26.Bxb7.

The rook on c2 and the knight are defenseless (attacked as many times as they are defended, at least) and White's bishop and knight can be captured with check. These facts suggest the double attack 25... Bb4:

A) 26.Rxc8 Bxc8 27.Rc1 Rxd2+ and 28... Ba6 - + [B].

B) 26.Rb2 Rxd2+ 27.Rxd2 Bxf3+ 28.Kxf3 Bxd2 - + [B].

C) 26.Bxb7 Rxc2 followed by 27... Rdxd2 - + [R].

D) 26.Rec1 Bxf3+ 27.Kxf3 Rxc2 28.Rxc2 Rxd2 - + [N].

E) 26.Nc4 Bxf3+ 27.Kxf3 Bxe1 - + [R].

A chess game begins symmetrically. Just like the human body, we have one of everything down the middle and two of everything down the sides. Except for pawns, of course. And fingers and toes. But apart from that, and the aqueducts and sanitation, we have one etc etc etc.

And the symmetry continues as the game unfolds. I move, you move, I move, you move. After you, sir. No, I insist, after you.

When we exchange pieces and pawns, most trades are equal. Pawn for pawn, rook for rook, queen for queen... continue until KvK and a peaceful draw.

And if that was all there was to chess, it would be a pretty dull game. It would be draughts, scrabble, sudoku. In a parallel universe, there might be a website called sudokugames.com where fans kibitz about how a Frank Marshallish character brilliantly wrote a 5 in the top left hand box and the audience showered the newspaper with gold coins. A move nearly as brilliant as Bobby Fischer-san putting an 8 in the lower middle box in the third game of the world championship against Petrosian-san.

The problem with Sudoku, my friends, is that it doesn't have moves like 11. Bxf6. With this move, white voluntarily exchanges a bishop for a knight. And that creates what Jeremy Silman calls an imbalance. Our starting symmetry has now been broken, and we have an intriguing question - which is better, the bishop or the knight?

Fast forward to our puzzle position, and we see that white's decision to trade bishop for knight hasn't worked out terribly well. The Bc5 is now the only piece left on the board that can contest dark squared diagonals. And the poor white knight on d2 is just pin-fodder.

And the rest is calculation, and not the kind where you suck on your pen as you squint at the newspaper and mutter "it can't be a 2 because there's one in the middle row, and the top left hand box needs a seven, which means that the bottom right hand box must be a 9...."

A) 26.Rxc8 Bxc8

A.1) 27.Rd1 Rxd2+ 28.Rxd2 Bxf3+ 29.Kxf3 Bxd2

A.2) 27.Re2 Rxd2 28.Bxb7 Rxe2+ (28.Rxd2 transposes to A.1)

B) 26.Bxb7 Rxc2

C) 26.Rb2 Rxd2+ 27.Rxd2 Bxf3+ 28.Kxf3 Bxd2

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After (a) 26. Rxc8 bxc8 white will lose the knight on d2.

(b) 26. Rec1 Rxc2 27. Rxc2 Rxd2+ 28. Rxd2 Bxf3+ 29. Kxf3 Bxd2 and black emerges a bishop up

(c) 26. Ne4 Rxc2+ winning a rook

(d) 26. Nc4 Bxf3+ 27. Kxf3 Bxe1 again winning a rook.

Other white moves are no better.

click for larger view

The exposed king position really hurts because by taking with check black forces 27 Rxd2, instead of the piece saving 27 Rxc8+.

Now, black wins a piece after 27..Bxd2.

click for larger view

Looking at <agb2002>'s analysis I can see that I missed a few possible defenses. Line D seems to be incorrect. After 26.Rec1 Bxf3+, 27.Nxf3 let's white off the hook. In that line I like 26...Rxc2 27.Rxc2 Rxd2+ 28.Rxd2 Bxf3+ 29.Kxf3 Bxd2 best. >

A.1) 27.Rd1 Rxd2+ 28.Rxd2 Bxf3+ 29.Kxf3 Bxd2>

J Lynch vs Michel

25. ... ?

Difficulty: Easy

Material is even,
but black has the bishop pair.

First I thought that Rxd2+ would be the answer,
but after some analysis I saw that black wouldn`t
win material.

Then, after some careful thought, I think I found the winning move:

25. ... Bb4!

With double attack on the rook and knight.

It seems to me that white cannot avoid losing
material.

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Rybka 4 x 64 blunders only

WHITE: depth : 22 : 5 min :
(-3.70):25.e5. Best, Nc4, =-0.42.

1. (-0.42): 25.Nc4 g5 26.e5 Ba6 27.Rd1 Rxd1 28.Bxd1 gxf4 29.gxf4 Rd8 30.Bf3 Bxc4 31.bxc4 Rd4 32.Kg3

2. (-0.53): 25.Re2 g5 26.Nc4 Kg7 27.h4 gxh4 28.gxh4 Ba6 29.Kh3 Rd4 30.Re1 Bxc4 31.Rxc4

Just the one blunder, but enough to ruin White's day.

Had the game continued.....

Rybka 4 x64: d: 24 : 7 min :